FINISHING WORK



FINISHING WORK
15.1. SPECIFICATIONS FOR 12 MM LIME PLASTER

15.1.1. Scaffolding - For all exposed brick work or tile work, double scaffolding independent of the work having two sets of vertical supports shall be provided. The supports shall be sound and strong, tied together with horizontal pieces over which scaffolding planks shall be fixed.

For all other brick work in buildings, single scaffolding shall be permitted. In such cases the inner end of the horizontal scaffolding pole shall rest in a hole provided only in the header course for the purpose.  Only one header for each pole shall be left out.  Such holes for scaffolding shall, however, not be allowed in pillars/columns less than one meter in width or immediately near the skew backs of arches. The holes left in masonry works for scaffolding purposes shall be filled and made good before plastering.

Note - In case of special type of brick work, scaffolding shall be got approved from engineer in advance.

15.1.2. Preparation of Surface - The joints shall be raked out properly. Dust and loose mortar shall be brushed out. Efflorescence if any shall be removed by brushing and scrapping. The surface shall then be thoroughly washed with water, cleaned and kept wet before plastering is commenced.

In case of concrete surface if a chemical retarder has been applied to the form work, the surface shall be roughened by wire brushing and all the resulting dust and loose particles cleaned off and care shall be taken that none of the retarders is left on the surface.

15.1.3. Mortar - The mortar of the specified mix shall be used.  Lime mortar shall be as specified.

15.1.4. Application of Plaster

15.1.4.1. Ceiling plaster shall be completed before commencement of wall plaster.

15.1.4.2. Plastering shall be started from the top and worked down towards the floor. All put-log holes shall be properly filled in advance of the plastering as the scaffolding is being taken down.  To ensure even thickness and a true surface, plaster about 15 x 15 cm shall be first applied, horizontally and vertically, at nor more than 2 meters intervals over the entire surface to serve as gauges. The surfaces of these gauged areas shall be truly in the plane of the finished plaster surface. The mortar shall then be laid on the wall, between the gauges with trowel.  The mortar shall be applied in a uniform surface slightly more than the specified thickness.  This shall be beaten with thin strips of bamboo about one meter long to ensure through filling of the joints, and then brought to a true surface, by working a wooden straight edge reaching across the gauges, with small upward and side ways movements at a time.  Finally the surface shall be finished off true with trowel or wooden float according as a smooth or a sandy granular texture is required. Excessive toweling or over working the float shall be avoided. During this process, a solution of lime putty shall be applied on the surface to make the later workable.

15.1.4.3. All corners, arises, angles and junctions shall be truly vertical or horizontal as the case may be and shall be carefully finished. Rounding or chamfering corners, arises, provision of grooves at junctions etc. where required shall be done without any extra payment. Such rounding, chamfering or grooving shall be carried out with proper templates or battens to the sizes required.

15.1.4.4. When suspending work at the end of the day, the plaster shall be left, cut clean to line both horizontally and vertically. When recommencing the plastering, the edge of the old work shall be scrapped cleaned and wetted with lime putty before plaster is applied to the adjacent areas, to enable the two to properly joint together. Plastering work shall be closed at the end of the day on the body of wall and not nearer than 15 cm to any corners or arises. It shall not be closed on the body of the features such as plasters, bands and cornices, nor at the corners of arises. Horizontal joints in plaster work shall not also occur on parapet tops and copings at these invariably lead to leakages.

No portion of the surface shall be left out initially to be patched up later on.

15.1.5. Finish - The plaster shall be finished to a true and plumb surface and to the proper degree of smoothness as required. The work shall be tested frequently as the work proceeds with a true straight edge not less than 2.5 m long and with plumb bobs. All horizontal lines and surfaces shall be tested with a level and all jambs and corners with a plumb bob as the work proceeds.

15.1.6. Thickness - The thickness of the plaster specified shall be measured exclusive of the thickness of key i.e., grooves or open joints in brick work. The average thickness of plaster shall not be less than the specified thickness, here 12 mm. The minimum thickness over any portion of the surface shall not be less than specified thickness by more than 3 mm. The average thickness should be regulated at the time of plastering by keeping suitable thickness of the gauges. Extra thickness required in dubbing behind rounding of corners at junctions of wall or in plastering of masonry cornices etc. will be ignored.

15.1.7. Curing - Curing shall be started 24 hours after finishing the plaster.  The plaster shall be kept wet for a period of seven days.  During this period, it shall be suitably protected from all damages at the contractor’s expense by such means as the engineer may approve. The dates on which the plastering is done shall be legibly marked on the various sections plastered so that curing for the specified period thereafter can be watched.

15.1.8. Precaution - Any cracks which appear in the surface and all portions which sound hollow when lapped, or are found to be soft or otherwise defective, shall be cut out in rectangular shape and redone as directed by the engineer.

i)  When ceiling plaster is done, it shall be finished to chamfered edge at an angle at its junction with a suitably tool when plaster is being done.  Similarly when the wall plaster is being done, it shall be kept separate from the ceiling plaster by a thin straight groove not deeper than 6 mm drawn with any suitable method with the wall while the plaster is green.

ii)  To prevent surface cracks appearing between junctions of column/ beam and walls, 150 mm wide chicken wire mesh should be fixed with U nails 150 mm centre to centre before plastering the junction. The plastering of walls and beam/column in one vertical plane should be carried out in one go.  For providing and fixing chicken wire mesh with U nails payment shall be made separately.

15.1.9. Measurements

15.1.9.1. Length and breadth shall be measured correct to a cm and its area shall be calculated in square meters correct to two places of decimal.

15.1.9.2. Thickness of the plaster shall be exclusive of the thickness of the key i.e., grooves, or open joints in brick work.

15.1.9.3 The measurement of wall plaster shall be taken between the walls or partitions (the dimensions before the plaster shall be taken) for the length and from the top of the floor or skirting to the ceiling for the height.  Depth of coves or cornices if any shall be deducted.

15.1.9.4. The following shall be measured separately from wall plaster.

a)  Plaster bands 30 cm wide and under

b) Cornice beadings and architraves or architraves moulded wholly in plaster.

c)  Circular work not exceeding 6 m in radius.

15.1.9.5. Plaster over masonry plasters will be measured and paid for as plaster only.

15.1.9.6. A coefficient of 1.63 shall be adopted for the measurement of one side plastering on honey comb work having 6 x 10 cm. opening.

15.1.9.7. Moulded cornices and coves

a)  Length shall be measured at the centre of the girth.

b)  Moulded cornices and coves shall be given in square meters the area being arrived at by multiplying length by the girth.

c)  Flat or weathered top to cornices when exceeding 15 cm in width shall not be included in the girth but measured with the general plaster work.

d)  Cornices which are curved in their length shall be measured separately.

15.1.9.8. Exterior plastering at a height greater than 10 m from average ground level shall be measured separately in each storey height.  Patch plastering (in repairs) shall be measured as plastering new work, where the patch exceed 2.5 sqm extra payment  being made for preparing old wall, such as dismantling old plaster, raking out the joints and cleaning the surface.  Where the patch does not exceed 2.5 sqm in area it shall be measured under the appropriate item under sub head ‘Repairs to Buildings’.

15.1.9.9. Deductions in measurements, for opening etc. will be regulated as follows

a)  No deduction will be made for openings or ends of joists, beams, posts, girders, steps etc. up to 0.5 sqm in area and no additions shall be made either, for the jambs, soffits and sills of such openings.  The above procedure will apply to both faces of wall.

b)  Deduction for opening exceeding 0.5 sqm but not exceeding 3 sqm each shall be made for reveals, jambs, soffits sills, sills, etc. of these openings.

1)  When both faces of walls are plastered with same plaster, deductions shall be made for one face only.

2)  When two faces of walls are plastered with different types of plaster or if one face is plastered and other is pointed or one face is plastered and other is unplastered, deduction shall be made from the plaster or pointing on the side of the frame for the doors, windows etc. on which width of reveals is less than that on the other side but on deduction shall be made on the other side.

Where width of reveals on both faces of wall is equal, deduction of 50% of area of opening on each face shall be made from area of plaster and / or pointing as the case may be.

3)  For opening having door frame equal to or projecting beyond thickness of wall, full    deduction for opening shall be made from each plastered face of wall.

Note - Different qualities of plastering referred in this para shall not include ‘18 mm plastering with terrazzo finish’ as given in para 15.13 as the method of measurement in the case of the later is different.  In such cases where the plaster on the other face consists of a plaster with terrazzo finish method of addition and deductions for the ordinary plaster face shall be regulated as if that face alone is plastered and the other is given an entirely different type of non-comparable treatment.

c)  For opening exceeding 3 sqm in area, deduction will be made in the measurements for the full opening of the wall treatment on both faces, while at the same time, jambs, sills and soffits will be measured for payment.

In measuring jambs, sills and soffits, deduction shall not be made for the area in contact with the frame of doors, windows etc.

15.1.10. Rate - The rate shall include the cost of all labour and materials involved in all the operations described above.

15.2. SPECIFICATIONS FOR 15 MM LIME PLASTER

15 mm thick lime plaster shall be done on rough side of single or half brick work.  The average thickness of plaster shall not be less than 15 mm and the minimum thickness of the plaster at any place shall not be less than 10 mm. All other details shall be as specified in 15.1.

15.3. SPECIFICATIONS FOR 18 MM LIME PLASTER (TWO COATS WORK)

15.3.1. The details of scaffolding and preparation of surface and mortar shall be as specified in 15.1.

15.3.2. Application of Plaster - The plaster shall be applied in two coats. I.e., 12 mm under coat and then 6 mm finishing coat and shall have an average final thickness of not less than 18 mm.

15.3.2.2.    12 mm under coat - This shall be applied in the same manner as specified under 12 mm lime plaster except that (a) the finishing after the mortar has been brought to a level with the wooden straight edge, shall be done with wooden float only (b) during the process lime putty  solution shall not be applied.

The surface shall be further roughened by furrowing about 2 mm deep with a scratching tool diagonally both ways to form a key for the finishing coat. The scratched lines shall be at not more than 15 cm apart.  The surface shall be kept wet till the finishing coat is applied.

15.3.2.3.   6 mm Finishing Coat - The finishing coat shall be applied a day or two after the under coat has set.  The latter shall not be allowed to dry out, before the finishing coat is laid on. The finishing coat shall be applied in a uniform thickness of slightly more than 6 mm. The method of application shall be as described except that the surface shall not be beaten with bamboo strips.  The final thickness of the top coat shall be 6 mm.

15.3.3. Thickness - The thickness of the under coat of plaster specified shall be exclusive of the thickness of key.  The average thickness of the under coat shall not be less than 12 mm whether the wall treated is of brick or stone. In the case of brick work the minimum thickness over any portion of the surface shall not be less than 10 mm while in the case of stone work, the minimum thickness over the bushing shall not be less than 6 mm.

15.3.4.   26 mm finishing coat shall be uniformly 6 mm thick over the under coat in the case of both brick and stone masonry.

15.3.5. Specifications for other details such as Finish, Curing, Precautions, Measurements, and Rate etc. shall be as described.

15.4. SPECIFICATIONS FOR LIME PUNNING

15.4.1. Scaffolding shall be as specified in 15.1.1

15.4.2. Mortar - The mortar for punning shall consist of 1 lime putty and 1 fine sand unless otherwise described in the item.  It shall be prepared as specified in section 0.5 of KBS.

15.4.3. Application - The surface of the under coat on which the punning is to be done shall be left rough.  The punning shall be applied, when the under coat is still green.  The mortar for punning shall be applied in a uniform layer slightly more than 3 mm thick between gauged pads, with which to ensure an even and uniformly thick surface by frequent checking with a wooden straight edge.  It shall be finished to an even and smooth surface with trowels.

All corners, arises, angles and junctions shall be truly vertical and horizontal as the case may be and shall be carefully and neatly finished.  Rounding or chamfering corners, arises, junctions etc. where required, shall be punned without any extra payment.  Such rounding, chamfering or grooving shall be carried out with proper templates or battens to the sizes required.

No portion of the surface shall be left out initially to be patched up later on.

15.4.4. Thickness - The thickness of the finished punning shall not be less than 3 mm thick.

15.4.5. Curing shall be started as soon as the punning has sufficiently hardened not to be damaged when watered, and in any case not earlier than 24 hours after the punning has been completed. The punning shall be kept wet for a period of at least 7 days.  During this period, it shall be suitably protected from all damages at the contractor’s expense by such means as the Engineer may approve. The dates on which the plastering is done shall be legibly marked on the various sections plastered so that curing for the specified period thereafter can be watched.

15.4.6. Specifications for finishing, precautions, etc. shall be as specified.

15.4.7. Measurements

15.4.7.1. The measurements for lime punning shall be taken over the finished work.  The length and breadth shall be measured correct to a cm.  The area shall be calculated in sqm correct to two places of decimal.

15.4.7.2. Punning over Plaster on bands, skirting, coping, cornices, drip courses, string courses etc. shall not be measured separately but only as wall surfaces. In these cases the measurements shall be taken girthed over the above features.

15.4.7.3. Punning over plaster on circular work also, of any radius shall be measured only as wall surfaces, and not separately.

15.4.7.4. Lime punning in patch repairs irrespective of the size of the patch shall be measured as new work, and in this case the rate shall include for cutting the patch to rectangular shape before lime punning.

15.4.7.5. Deductions in measurements for openings shall be regulated generally as described in 15.1.9.9

15.4.8. Rate - The rate shall include the cost of all labour and materials involved in all the operations described above.

15.5. SPECIFICATIONS FOR CEMENT PLASTERING

15.5.0. The cement plaster shall be 12 mm, 15 mm or 20 mm thick as specified in the item.

15.5.1. Scaffolding and preparation of surface shall be as specified in 15.1

15.5.2 Mortar - The mortar of the specified mix using the type of sand described in the item shall be used.  It shall be as specified.  For external work and under coat work, the fine aggregate shall conform to grading IV. For finishing cost work the fine aggregate conforming to grading zone V shall be used.

15.5.3. Application - The specifications as in 15.1.4 shall apply except in the following respects -

a)  Beating with thin bamboo strips shall not be done on the cement plaster, and

b)  No lime putty solution shall be applied on the face when finishing.  Further the plastering and finishing shall be completed within half an hour of adding water to the dry mortar.

15.5.4. Thickness - Where the thickness required as per description of the item is 20 mm the average thickness of the plaster shall not be less than 20 mm whether the wall treated is of brick or stone. In the case of brick work, the minimum thickness over any portion of the surface shall be not less than 15 mm while in case of stone work the minimum thickness over the bushings shall be not less than 12 mm.

15.5.5. Curing - Curing shall be started as soon as the plaster has hardened sufficiently not to be damaged when watered.

The plaster shall be kept wet for a period of at least 7 days. During this period, it shall be suitably protected from all damages at the contractor’s expense by such means as the engineer may approve. The dates on which the plastering is done shall be legibly marked on the various sections plastered so that curing for the specified period thereafter can be watched.

Specifications for Finish, Precautions, Measurements and Rate shall be as described in 15.1

15.6. SPECIFICATIONS FOR CEMENT PLASTER WITH A FLOATING COAT OF NEAT CEMENT

15.6.0. The cement plaster shall be 12, 15 or 20 mm thick, finished with a floating coat of neat cement, as described in the item.

15.6.1. Specifications for this item of work shall be same as described except for the additional floating coat which shall be carried out as below.

When the plaster has been brought to a true surface with the wooden straight edge (clause 13.5.3 It shall be uniformly treated over its entire area with a paste of neat cement and rubbed smooth, so that the whole surface is covered with neat cement coating. The quantity of cement applied for floating coat shall be 1 kg per sqm.  Smooth finishing shall be completed with trowel immediately and in no case later than half an hour of adding water to the plaster mix.  The rest of the specifications as described in 15.5.3 shall apply.

15.7. SPECIFICATIONS FOR 18 MM CEMENT PLASTER (TWO COAT WORK)

15.7.1. The specification for scaffolding and preparation of surface shall be as described in 15.5

15.7.2. Mortar - The mix and type of fine aggregate specified in the description of the item shall be used for the respective coats. It shall be as specified in section 0.5.  Generally the mix of the finishing coat shall not be richer than the under coat unless otherwise described in item.

Generally coarse sand shall be used for the under coat and fine sand for the finishing coat, unless otherwise specified for external work and under coat work, the fine aggregate shall conform to grading zone IV. For finishing coat work the fine aggregate conforming to grading zone V shall be used.

15.7.3. Application

15.7.3.1. The plaster shall be applied in two coats i.e. 12 mm under coat and then 6 mm finishing coat and shall have an average total thickness of not less than 18 mm.

15.7.3.2. 12 mm under coat -This shall be applied as specified except that when the plaster has been brought to a true surface a wooden straight edge and the surface shall be left rough and furrowed 2 mm deep with a scratching tool diagonally both ways, to form key for the finishing coat is applied.

15.7.3.3. 6 mm finishing coat - The finishing coat shall be applied after the under coat has sufficiently set but not dried and in any case within 48 hours and finished in the manner as specified.

15.7.4. Specifications for Curing, Finishing, Precautions, Measurements and Rate shall be as described in 15.5

15.8. SPECIFICATIONS FOR 6 MM CEMENT PLASTER ON CEMENT CONCRETE AND REINFORCED CEMENT CONCRETE WORK

15.8.0 Scaffolding - Stage scaffolding shall be provided for the work.  This shall be independent of the walls.

15.8.1. Preparation of Surface - Projecting burrs of mortar formed due to the gaps at joints in shuttering shall be removed. The surface shall be scrubbed clean with wire brushes. In addition concrete surface to be plastered shall be pock marked with a pointed tool, at spacing of not more than 5 cm centers, the pock being made not less than 3 mm deep.  This is to ensure a proper key for the plaster.  The mortar shall be washed off and surface, cleaned of all oil, grease etc. and well wetted before the plaster is applied.

15.8.2. Mortars - Mortar of the specified mix using the types of sand described in the item shall be used. It shall be as specified.

15.8.3. Application -To ensure even thickness and a true surface, gauges of plaster 15 x 15 cm, shall be first applied at not more than 1.5 m intervals in both directions to serve as guides for the plastering. Surface of these gauged areas shall be truly in the plane of the finished plaster surface.  The plaster shall be then applied in a uniform surface to a thickness slightly more than the specified thickness and shall then be brought to true and even surface by working a wooden straight edge reaching across the gauges.   Finally the surface shall be finished true with a trowel or with wooden float to give a smooth or sandy granular texture as required. Excess trowel ling or over working of the floats shall be avoided. The plastering and finishing shall be completed within half an hour of adding water to the dry mortar.

15.8.4. Plastering of ceiling shall not be commenced until the slab above has been finished and centering has been removed. In case of ceiling of roof slabs, plaster shall not be commenced until the terrace work has been completed. These precautions are necessary in order that the ceiling plaster is not disturbed by the vibrations set up in the above operations.

15.8.5. Finish - The plaster shall be finished to a true and plumb surface and to the proper degree of smoothness as required.  The work shall be tested 15.8.5 frequently as the work proceeds with a true straight edge not less than 2.5 m long and with plumb bobs.  All horizontal lines and surfaces shall be tested with a level and all jambs and corners with a plumb bob as the work proceeds.

15.8.6. Thickness - The average thickness of plaster shall not be less than 6 mm. The minimum thickness over any portion of the surface shall not be less than 5 mm.

15.8.7. Curing - The specifications shall be as detailed in 15.5

15.8.8. Precautions - These shall be as described in 15.1.8.

15.8.9. Measurements

15.8.9.1. Length and breadth shall be measured correct to a cm. and its area shall be calculated in sq.m correct to two places of decimal.  Dimensions before plastering shall be taken.

15.8.9.2. Thickness of plaster shall be exclusive of the thickness of the key i.e., depth or rock marks and hacking.

15.8.9.3. Plastering on ceiling at height greater than 5 m above the corresponding floor level shall be so described and shall be measured separately stating the height in stages of 1 m or part thereof.

15.8.9.4. Plastering on the sides and soffits of the projected beams of ceiling at a height greater than 5 m above the corresponding floor level shall be measured and added to the quantity as measured under 15.8.9.3.

15.8.9.5. Plastering on spherical and groined ceiling and circular work not exceeding 6 m in radius, shall be measured and paid for separately.

15.8.9.6. Flowing soffits (Viz. portion under spiral stair case etc.) shall be measured and paid for separately.

15.8.9.7. Ribs and mouldings on ceiling shall be measured as for cornices; deductions being made from the plastering on ceiling in case the width of the moulding exceed 15 cm.

15.8.9.8. The mode of measurement of exterior plaster and patch plastering (in repairs) shall be as laid down in 15.1.9.8

15.8.9.9. Deduction shall not be made for openings or for ends of columns, or columns caps of 0.5 sqm each in area and under. No additions will be made either for the plastering of the sides of such openings.  For openings etc. of areas exceeding 0.5 sqm deduction will be made for the full opening but the sides of such openings shall be measured for payment.

15.8.10. Rate - The rate shall include the cost of all labour and materials involved in all the operations described above.

15.9. SPECIFICATIONS FOR 6 MM CEMENT PLASTER FOR SLAB BEARING

15.9.0. Cement plaster shall be 6 mm thick finished with a floating coat of neat cement and thick coat of lime wash on top of walls for bearing of slabs.

15.9.1. Application - The plaster shall be applied over the cleaned and wetted surface of the wall. When the plaster has been brought to a true surface with a wooden  straight edge (Clause 15.5.3) it shall be uniformly treated over its entire area with a paste of neat cement and rubbed smooth, so that the whole surface is covered with neat cement coating.  The quantity of cement applied for floating coat shall be 1 kg per sqm. Smooth finishing shall be completed with trowel immediately and in no case later than half an hour of adding water to the plaster mix.  The rest of the specifications described in 15.5.3 shall apply.

15.9.2. Lime wash - This shall be applied in a thick coat after curing the plaster for three day

15.9.3. Measurements - Length and breadth shall be measured correct to a cm and area worked out in sqm correct to two places of decimal.

15.9.4. Rate - The rate shall include the cost of all labour and materials involved in all the operations described above.

15.10. SPECIFICATIONS FOR NEAT CEMENT PUNNING

15.10.1. The specifications given for floating coat as described in 15.6.1 shall apply.

15.10.2. Specification for scaffolding and curing shall be as described in 15.5.1 and 15.5.5. Specifications for Finish and Precautions shall be as described in 15.1.5 and 15.1.8.

15.10.3 Measurements shall be as described in 15.4.7

15.10.4. Rate - The rate shall include the cost of all labour and materials involved in all the operations described above.

15.11. SPECIFICATIONS FOR ROUGH CAST PLASTER

15.11.0. Rough cast finish comprises of a mixture of sand and gravel in specified proportions dashed over a freshly plastered surface.

15.11.1. Scaffolding - Scaffolding shall be done as specified in 15.1

15.11.2. Preparation of Surface - The joints shall be raked out, dust and loose mortar, shall be brushed out.  The surface shall be thoroughly washed with water, cleaned and kept wet before plastering is commenced.

15.11.3. Mortar - Mortar of specified mix using the type of sand described in the item shall be used, where coarse sand is to be used, the fineness, modulus of the sand shall not be less than 2.5 mm.

15.11.4. Application

15.11.4.1. The plaster base over which rough cast finish is to be applied shall consist of two coats, under layer 12 mm thick and top layer 10 mm.

15.11.4.2. 12 mm under layer - This shall be applied in the same manner as specified under 18 mm lime plaster except that the surface shall not be beaten with bamboo strips.

15.11.4.3. Top Layer - The top layer shall be applied a day or two after the under layer has taken initial set.  The latter shall not be allowed to dry out, before the top layer is laid on.  The mortar used for applying top layer shall be sufficiently plastic and of rich mix 1:3 (1 cement - 3 fine sand) or as otherwise specified so that the mix of sand and gravel gets well pitched with the plaster surface. In order to make the base plastic, about 10% of finely grouted hydrated lime by volume of cement, shall be added when preparing mortar for the top layer.

15.11.5. Finish - It shall be ensured that the base surface which is to receive rough cast mixture is in plastic state. The rough cast mixture shall consist of sand or grovel or crushed stone of uniform colour from 2.36 mm to 12.5 mm or as specified and in the proportions as specified accurately to the effect required.  The mixture shall be wetted and shall be dashed on the plaster base in plastic state by hand scoop so that the mix gets well pitched into the plaster base. The mix shall again be dashed over the vacant spaces if any so that the surface represents homogeneous surfaces of sand mixed with gravel. A sample of rough cast plaster shall be got approved by the Engineer.

15.11.6. Specification for other details like precautions, measurement and rate shall be as described in 15.11

15.12. SPECIFICATIONS FOR PEBBLE DASH FINISH (INSITU WORK)

15.12.1. The specification shall be the same as for rough cast plaster, except that the washed pebble or crushed stone graded from 12.5 mm to 6.3 mm or as specified shall be dashed over the plaster base and the vacant spaces if any shall be filled in by pressing pebbles or crushed stone as specified by hand, so that the finished surface represents a homogeneous surface.

15.12.2. Specifications for scaffolding, preparation of surface, Mortar, Measurements and Rate shall be as described in 15.11

15.13. SPECIFICATIONS FOR 18 MM PLASTERING WITH TERRAZZO FINISH

15.13.1. Scaffolding - Double scaffolding shall invariably be adopted.

15.13.2. Preparation of Surface - The joints shall be raked out properly.  Dust and loose mortar shall be brushed out. Efflorescence, if any, shall be removed by brushing and scrapping. The surface shall then be thoroughly washed with water, cleaned and kept wet before plastering is commenced.

In case of concrete surface if a chemical retarder has been applied to the form work, the surface shall be roughened by wire brushing and all the resulting dust and loose particles cleaned off and care shall be taken that none of the retarders is left on the surface.

15.13.3. Mortar

15.3.3.1. The mortar shall be prepared as specified.

15.13.3.1. 12 mm under coat - This shall generally consist of cement mortar 1:3 unless otherwise specified in the item.

15.13.3.2. 6 mm Top Coat - This specification as above shall hold good as far as possible.

15.13.4. Applications

15.13.4.1. 12 mm under coat  - This shall be applied in the manner specified in 15.5.3 except that when the plaster has been brought to a true surface with a wooden straight edge, the surface shall be left rough and furrowed 2 mm deep with a scratching tool diagonally both ways to form key for the top coat. The scratched lines shall be at not more than 15 cm apart. The surface shall be kept wet till the finishing coat is applied.

15.13.4.2. 6 mm top coat - The top coat shall be applied after the under coat has sufficiently set but not dried, and in any case within 48 hours and finished in the same manner as specified under “ 40 mm marble chips flooring “ as far as possible.

15.13.4.3. All corners, risers, angles and junctions shall be truly vertical or horizontal as the case may be, risers shall be carefully and neatly finished and rubbed smooth. Rounding or chamfering corners, risers, junctions etc. where required shall be true to template and shall be carried out without any extra payment.

15.13.5. Finish - The finished surface shall be smooth, highly polished and absolutely even so that when light from side ways is reflected on it, it does not show any kind of waviness.

15.13.6. Thickness

15.13.6.1. The thickness of the under coat of plaster specified shall be exclusive of the thickness of key.  The average thickness of the under coat shall not be less than 12 mm whether the wall treated is of brick or stone.  In the case of brick work the minimum thickness over any portion of the surface shall not be less than 10 mm while in the case of stone work, the minimum thickness over the bushing shall not be less than 6 mm.

15.13.6.2 6 mm finishing coat shall be uniformly 6 mm thick over the under coat in the case of both brick and stone masonry.

15.13.7 Curing - Curing shall be started as soon as the plaster has hardened sufficiently not to be damaged when watered.

The plaster shall be kept wet for a period of at least 7 days.  During this period, it shall be suitably protected from all damages at the contractor’s expense by such means as the Engineer may approve. The dates on which the plastering is done shall be legibly marked on the various sections plastered so that curing for the specified period thereafter can be watched.

15.13.8 Precautions - Any cracks which appear in the surface and all portions, which sound hollow when trapped, or are found to be soft or otherwise defective, shall be cut out in rectangular shape and redone as directed by the Engineer.  In addition care shall be taken that finish of the rectified work is indistinguishable from the rest of the portions and does not show as a patch.

15.13.9. Measurements

15.13.9.1 Measurement of length and breadth shall be correct to a cm and its area shall be calculated correct to two places of decimal. The measurement of plaster shall be taken between the wall or partition (being the dimension before plastering).

15.13.9.2 Measurement of the work as actually done with all deductions of opening etc., addition of jambs, sills and soffits shall be taken.  However, openings less than 5 sq dm in area will be ignored.

15.13.9.3 Skirting not exceeding 30 cm in height shall be measured in sqm separately, stating the number of coats, thickness of each coat and whether plain, chamfered or beaded on top.

15.13.9.4. Circular work not exceeding 6 m in radius shall also be separately measured.

15.13.9.5. Moulded cornices and coves shall be measured as follows -

a)  Length shall be measured at the centre of the girth.

b) Moulded cornices and coves shall be given in sqm the area being arrived at by multiplying length by the girth.

c)  Flat or weathered top to cornices when exceeding 15 cm in width shall not be included in the girth but measured with the general plaster work.

d)  Cornices which are curved in their length shall be measured separately.

15.13.10. Rate - The rate shall include the cost of all labour and materials involved in the operations described above.

15.14. SPECIFICATIONS FOR 18 MM ARTIFICIAL RED STONE PLASTER

15.14.1. The specification for scaffolding and preparation of surface shall be as described in 15.5

15.14.2. Mortar

15.14.2.1. 12 mm under coat - Mortar of the mix and type of sand specified in the description of the item shall be used. This shall be generally (1:4) cement mortar using coarse sand, unless described otherwise.

15.14.2.2. 6 mm finishing coat- This shall consist of cement, marble dust and stone dust in the ratio of 1-1-3 mixed with red oxide at the rate of 15.4 kg per quintal of cement or as determined at site to obtain a shade matching red sand stone.  The red oxide used should be of approved make.  The colour shall be mixed thoroughly with dry cement, and then the mortar shall be mixed in the same manner as ordinary cement mortar, using the pigmented cement and stone dust and marble dust mixture.

15.14.3. Application, Thickness, Curing Finishing, precaution and Rate shall be as specified except in 15.7 that the surface finish shall be neither too neither rough nor too smooth but should resemble red stone work in texture.

15.14.4. Measurements - These shall be as specified in 15.13.9. Lining out plaster in imitation of stone or concrete block walling shall be given in sqm as ‘extra over’ general plaster work.

15.15. SPECIFICATIONS FOR PLAIN BANDS OF CEMENT MORTAR

‘Plain band’ is a plaster strip of uniform width not exceeding 30 cm and of uniform thickness, provided for decorative or other purpose flush with, sunk below or projecting beyond, the wall plaster.  A flush band is one where due to the difference in mix or shade of the mortar, the band is executed as a separate and distinct operation from the wall plaster.

15.15.1. Thickness - The thickness of a raised band is the thickness of the projection beyond the plane of the wall plaster. In the case of a flush or a sunken band, the thickness will be the thickness of the plaster measured from the untreated wall surface.

15.15.2. Preparation of surfaces and application

15.15.2.1. In the case of flush or sunk bands the joints shall be raked out properly.  Dust and loose mortar shall be brushed out. Efflorescence if any shall be removed by brushing the scraping. The surface shall then be thoroughly washed with water, cleaned and kept wet before plastering is commenced.

15.15.2.2. In case of concrete surface if a chemical retarder has been applied to the form work, the surface shall be roughened buy wire brushing and all the resulting dust and loose particles cleaned off and care shall be taken that none of the retarders is left on the surface.

15.15.2.3 In case of raised band, the surface shall be prepared as specified except in following respects (a) beating with thin bamboo strips shall not be done and (b) the lime putty solution shall be applied on a surface when Finishing. The surface is the wall plaster behind the band shall be left rough and furrowed 2 mm deep with a scratching tool, diagonally both ways to form key for the band. No reduction in the rate for the above backing wall plaster shall, however, be made for not finishing the same smooth.

15.15.3. Mortar - Mortar of the mix and type of sand specified in the description of the item shall be used.

15.15.4. Finish - The bands shall be finished exactly to the size as shown in the drawings. The horizontal or vertical lines of bands shall be truly parallel and straight and the surface shall be finished truly plane and smooth.  The lines and surfaces shall be checked with fine threads for straightness, level and accuracy.

15.15.5. Scaffolding, Curing and Precaution shall be as described in 15.5

15.15.6. Measurements - Length will be measured in running meters correct to a cm.  The length shall be taken along the finished face. The width shall not be measured by girth. For width of band 30 cm or below, the width shall be measured in cm correct to 5 mm.  The quantity shall be calculated in meter-cm units.

15.15.7. Rate - The rate shall include the cost of all labour and materials involved in all the operations described above. Nothing extra shall be paid for miters, stops nor for bands on curved surfaces of whatever radius they may be.  The rate is also inclusive of all rounding or chamfering at corners, risers, providing grooves at junctions etc.

15.16. SPECIFICATIONS FOR MOULDED BANDS OF CEMENT MORTAR (SINGLE COAT WORK)

Moulded band is a plaster strip of uniform width but with varying thickness across its section formed over wall plaster for decorative purposes.  The sectional periphery of the band is formed by a combination of straight lines or of curves or of straight lines and curves.

15.16.1. Thickness -    The higher thickness stipulated in the description of the item shall refer to the upper limiting thickness of the moulding at its most project portion, measured from the wall plaster.

Preparation of Surface, Mortar, Scaffolding, Curing and Precautions shall be as specified in 15.15

15.16.3. Application and finish - Proper templates conforming accurately to the sectional periphery of the moulded band shall be got approved, before use.  The finished band shall be true to the template at all sections. The lines of the band shall be truly parallel and straight and surfaces smoothly finished.

15.16.4 Measurements - The width of the band 30 cm or below shall be measured in cm correct to 5 mm and shall be measured along the sectional periphery of the moulded band from wall plaster face to wall plaster face. The length shall be measured, in running meters correct to a cm.  It shall be taken along the finished of the band at the centre of its girth. The quantity should be calculated in meter-cm units.

15.16.5. Rate - The rate shall include the cost of all labour and materials involved in all the operations described above. Nothing extra shall be paid for mitres, stops or for bands on curved surfaces of whatever radius they may be.  The rate is also inclusive of all rounding or chamfering at corners, arisers, etc.

15.17. SPECIFICATIONS FOR MOULDED BANDS OF CEMENT MORTAR (TWO COAT WORK)

15.17.0. Moulded band is a plaster strip of uniform width but with varying thickness across its section formed over wall plaster for decorative purposes. The sectional periphery of the band is formed by a combination of straight lines or of curves or of straight lines and curves.

5.17.1. Thickness -The higher thickness stipulated for the under coat in the description of the item shall refer to the upper limiting thickness of the under coat of the moulding at its most projected portion from the wall plaster.

The thickness stipulated for the finishing coat is the uniform thickness of the finished peripheral surface of the moulded band from the under coat.

15.17.2. Mortar -   The under coat shall consist of cement mortar 1:5 (1 cement: 5 coarse sand) and the top coat shall be of cement mortar 1:4 (1 cement: 4 fine sand) unless otherwise specified in the description of item.

15.17.3. Application and finish - Proper templates conforming to the sectional periphery of the moulded band as at the stages of the under coat and the finished coat shall be made and got approved and used at the proper stages in executing the bands to true and accurate profile. The lines of the bands as finally completed shall be truly parallel and straight and the surfaces smoothly finished.

15.17.4. All other details shall be as specified in 15.16

15.18. SPECIFICATIONS FOR CEMENT LIME PLASTER (SINGLE COAT WORK)

15.18.1. The cement lime plaster shall be 12 mm or 15 mm as specified in the item.

15.18.2. Mortar - The mortar of the mix and types of sand specified in the description of the item shall be used.  The cement lime mortar shall be as specified.

15.18.3. Application - It shall be as specified except that the plastering and finishing shall be completed within half an hour of adding slurry of lime putty to the dry cement sand mixture or mixing cement to ground lime mortar.

15.18.4. Specifications for scaffolding, Preparation of surface, Finish, Thickness, Curing, Precautions, Measurements and Rate shall be as described.

15.19. SPECIFICATIONS FOR CEMENT LIME PLASTER (TWO COAT WORK)

15.19.1. It shall be 18 mm thick unless otherwise specified.

15.19.2. Mortar -  Mortar of the mix and type of sand specified in the description of item shall be used. The under coat may be of either cement mortar or cement lime mortar as specified.

Generally the mix of under coat shall not be weaker than the finishing coat unless otherwise specified.  Generally coarse sand shall be used for the under coat and fine sand for the finishing coat unless otherwise specified.

15.19.3. The application shall be as specified in 15.7.3

15.19.4. Curing -  Curing shall be started as soon as the plaster has hardened smoothly not to be damaged when watered.

The plaster shall be kept wet for a period of at least 7 days.  During this period it shall be suitably protected from all damages at the contractor’s expense by such means as the Engineer may approve.  The dates on which the plastering is done shall be legibly marked on the various sections plastered so that curing for the specified period thereafter can be watched.

15.19.5 Specifications for scaffolding, Preparation of surface, finish, precautions, measurements and Rate shall be as specified in 15.1

15.20. SPECIFICATIONS FOR LIME PLASTER OF MARBLE SHADE

15.20.1. Scaffolding and Preparation of surface shall be as specified in 15.7 and 15.20.2.

15.20.2. Mortar and application - The work shall consist of three coats. First 12 mm under coat, then 6 mm middle coat and finally a brushed and polishing finishing coat. 

15.20.2.1. 12 mm under coat- Mortar of the mix and type of sand specified in the description of the item shall be used. This shall be generally 1:4 cement mortar using coarse sand, unless otherwise described in the item.  The application shall be as described.

15.20.2.2. 6 mm middle coat - This shall consist of Makrana Lime Paste, Fine marble chips and marble dust mixed in the ratio 2:1:2 (2 Makrana lime paste - 1 fine marble chips - 2 marble dust).  The lime paste shall be prepared by mixing lime in water and allowing the same to settle over night.  The water is decanted off next morning, and fresh water is added to lime and then stirred.  This process is repeated for a week and the lime paste is obtained the middle coat of the above specified mix shall be applied in 6 mm thick layer and finished smooth.  The surface shall be wetted for 7 days and then allowed to dry for about one month if it is in summer and two months if in winter.

15.20.2.4. Finishing coat - Makrana lime paste shall be prepared as detailed in the preceding para. It shall be mixed with curd in the proportion of 1 cum of paste - 16 kg of curd. This shall be screened through a fine muslin cloth and powdered mishri (crystallized sugar) dissolved with it at the rate of 16 kg per cum of paste.  The mixture so prepared shall have the consistency of cream.  It shall be applied with a brush on the rendered surface. The finishing coat is kept wet for four days and allowed to dry for seven days.  The surface shall then be rubbed with round glass or Mohur stone till it gets highly polished.  Finally the surface is rubbed with a fine muslin cloth and soap stone powder using coconut water. This shall be continued till a finally glazed surface is obtained.

15.20.3. Thickness, Curing, Finish, Precaution and Rate shall be as specified in 15.7.

15.20.4. Measurements and rate - These shall be as specified in 15.13.9 and 15.13.10

15.21. SPECIFICATIONS FOR LIME SURKHI PLASTER

15.21.0.   12 mm Lime Surkhi plaster

15.21.1.1. Mortar - Mortar of the mix and type of sand specified in the description of item shall be used. The lime surkhi mortar shall be as specified.

15.21.1.2. Specifications for scaffolding, Preparation of surface, Application, Thickness, Curing, Finish, Precautions, Measurements and Rate shall be as specified.

15.21.2. 18 mm Lime Surkhi plaster (two coat works)

15.21.2.1. Mortar - Mortar of the mix and type of sand as specified in the description of the item shall be used. The same mortar will be used for both under coat and finishing coat.

The lime surkhi mortar shall be as specified in section 0.5

15.21.2.2. Specifications for Scaffolding, Preparation of Surface, application, thickness, curing, Finishing, Precaution, Measurements and Rate shall be as specified in 15.3

15.22. SPECIFICATIONS FOR CEMENT WATER PROOFING COMPOUND

It shall be used for cement mortar for plastering or concrete work.

15.22.1. Water proofing compound - Integral cement water proofing compound conforming to IS: 2645-1975 and of approved brand and manufacture, enlisted by the engineer from time to time shall be used.

15.22.2. The contractor shall bring the materials to the site in their original packing. The containers will be opened and the material mixed with dry cement in the proportion by weight, recommended by the manufacturers or as specifically described in the description of the item.  Care shall be taken in mixing, to see that the water proofing material gets well and integrally mixed with the cement and does not run out separately when water is added.

15.22.3. It shall be measured by weight.

15.22.4 The rate shall include the cost of all labour and materials involved in all the operations described above.

15.23. SPECIFICATIONS FOR 18 MM MUD PLASTER (TWO COATS)

15.23.1. Scaffolding - Single scaffolding shall be done as specified.

15.23.2. Preparation of surface - The joints shall be raked out and surface washed of all dust and allowed to dry before plaster is applied.

15.23.3. Mortar - Mud mortar shall be prepared from good brick earth.  This shall be free from grass roots, gravel Kankar etc. The earth shall contain no efflorescent salts nor shall it be collected from a locality where there are white ants.  The earth shall be reduced to a fine powdered state and mixed with plenty of water in a pit, adding chopped straw at about 33 kg per cum of earth.

The mixture of earth, straw and water shall be allowed to mature for not less than 4 days. During this period it shall be worked up at intervals with foot and / or showels so that it is plugged into a homogeneous mixture.

The mortar when ready shall be of such consistency that it will readily slide off the face of trowel but shall not be so wet that the mortar parts into large drops while falling.

15.23.4. Application - Plastering shall be started from the top and worked towards the grounds.

The plaster shall be applied in two coats of 12 mm and 6 mm thickness. The prepared mixture shall be applied to the surface in a uniform coat of average thickness of 12 mm and then smoothened and made even with a straight edge and with floats. This shall be allowed to set but not to become dry before the second coat is applied.  The latter shall be 6 mm thick uniform throughout.  It shall be finally polished with a trowel after it has been smoothened with wooden floats. All corners, arises, angles and junctions shall be truly vertical or horizontal as the case may be, and shall be carefully and neatly finished.  Rounding and chamfering corners, arises, grooves at junctions etc. where required, shall be done without any extra payments.  Such rounding, chamfering and grooving shall be carried out with proper templates or battens to the sizes as required.

15.23.6. Finish - The plaster shall be finished to a true and plumb surface and to the proper degree of smoothness as required.  The work shall be tested frequently as the work proceeds with a true straight edge not less than 2.5 m long and with plumb box.  All horizontal lines and surfaces shall be tested with a level and all jambs and corners with a plumb box as the work proceeds.

15.23.7. Precautions - No curing shall be done.  The surface shall be protected from damage till it dries out.  Any cracks that open out during drying shall be opened out and thoroughly repaired with mixture of clay and cow dung.  Any portions which sound hollow when tapped shall also be redone after cutting out the hollow portions.

15.23.8. Thickness - The average thickness of the finished plaster excluding the key of the joints shall not be less than 18 mm.  The minimum thickness of the plaster over any portion of the wall of brick work shall not be less than 15 mm at any point while in the case of stone walls, this shall not be less than 12 mm over the bushings.

15.23.9. Measurements - The specifications for measurements shall be as described except for the following.

All bands and skirtings irrespective of width, moulded beadings, architrave and archivolt bands and circular work of any radius shall be measured and paid for under plastering areas only and not separately.

15.23.10. Rate - The rate shall include the cost of all labour and materials involved in all the operations described above.

15.24. SPECIFICATIONS FOR POINTING ON BRICK WORK, TILE WORK AND STONE WORK

15.24.0. Pointing shall be of the type shown in figure below

15.24.1. Scaffolding - For all exposed brick work or tile work, independent double scaffolding having two sets of vertical supports shall be provided. The supports shall be sound and strong tied together with horizontal pieces over which scaffolding planks shall be fixed.

All other brick work in building, single scaffolding shall be permitted. In such cases, the inner end of the horizontal scaffolding pole and shall rest in a hole provided only in the header course for the purpose.  Only one header for each pole shall be left out.  Such holes for scaffolding shall, however, not be allowed in pillars/columns less than one meter in width, or immediately near the skew backs of arches.  The holes left in masonry works for scaffolding purposes shall be filled and made good before plastering.

Note - In case of special type of brick work, scaffolding shall be got approved from Engineer in advance.

15.24.2. Preparation of surface -The joints shall be raked out properly. Dust and loose mortar shall be brushed out. Efflorescence if any shall be removed by brushing and scraping. The surface shall then be thoroughly washed with water, cleaned and kept wet before pointing is commenced.

In case of concrete surface if a chemical retarder has been applied to the form work, the surface shall be roughened by wire brushing and all the resulting dust and loose particles cleaned off and care shall be taken that none of the retarders is left on the surface.

The joints shall be raked to such a depth that the minimum depth of a new mortar measured from either the sunken surface of the finished pointing or from the edge of the brick shall not be less than 12 mm.

15.24.3. Mortar - Mortar of specified mix shall be used.  It shall be as specified.

15.24.4. Application and finishing

15.24.4.1. The mortar shall be pressed into the raked out joints, with a pointing trowel, either flush, sunk or raised, according to the type of pointing required. The mortar shall not spread over the corner, edges or surface of the masonry.  The pointing shall then be finished with the proper tool, in the manner described below -

15.24.4.2. Flush Pointing - The mortar shall be pressed into the joints and shall be finished off flush and level with the edges of the bricks, tiles or stones so as to give a smooth appearance. The edges shall be neatly trimmed with a trowel and straight edge.

15.24.4.3. Ruled Pointing - The joints shall be initially formed as for flush pointing and then while the mortar is still green, a groove of shape and size as shown in drawings or as instructed, shall be formed by running a forming tool, straight along the centre line of the joints.   This operation shall be continued till a smooth and hard surface is obtained. The vertical joints shall also be finished in a similar way.  The vertical lines shall make true right angles at their junctions with the horizontal lines and shall not project beyond the same.

15.24.4.4. Cut or weather struck pointing - The mortar shall first be pressed into the joints. The top of the horizontal joints shall then be neatly pressed back about 3 mm or as directed, with the pointing tool so that the joints are sloping from top to bottom.

The vertical joints shall be ruled pointed. The functions of vertical joints with the horizontal joints shall be at true right angles.

15.24.4.5.  Raised and Cut Pointing - Raised and cut pointing shall project from the wall facing with its edges cut parallel so as to have a uniformly raised sand about 6 mm raised and width 10 mm more as directed.

The superfluous mortar shall then be cut off from the edges of the lines and the surface of the masonry shall also be cleaned off all mortar.  The finish shall be such that the pointing is to the exact size and shape required and the edges are straight, neat and clean.

15.24.5. Curing - The pointing shall be kept wet for seven days.  During this period it shall be suitably protected from all damages.

The pointing lines shall be truly horizontal and vertical except where the joints are slanting as in rubble random masonry.  Lines of joints from different directions should meet neatly at the junctions instead of crossing beyond.

Measurements

15.24.6.1. Length and breadth shall be measured correct to a cm and its area shall be calculated in square meters up to two places of decimal.

15.24.6.2. The various types of pointing for example, struck, keyed, flush, truck, etc. shall each be measured separately.

15.24.6.3. Pointing on different types of walls, floors, roofs, etc. shall each be measured separately.  The type and material of the surface to be pointed shall be described.

15.24.6.4. Pointing in a single detached joint as for flashing shall be given in running meters.

15.24.6.5. For jambs, soffits, sills, etc. for opening not exceeding 0.5 sqm each in area, ends of joists, beams, posts, girders, steps, etc. not exceeding 0.5 sqm each in area and opening not exceeding 3 sqm each deductions and additions shall be made in the following way, in case of pointing on external face only.

a)  No deductions shall be made for ends of joists beams, posts etc. and openings not exceeding 0.5 sqm each, and no addition shall be made for reveals, jambs, soffits, sills, etc. of these openings.

b)  Deductions for openings exceeding 0.5 sqm but not exceeding 3 sqm each shall be made as follows and no additions shall be made for reveals, jambs, soffits, sills, etc. for these openings.

c)  When both the faces of the wall are pointed with the same pointing deduction shall be made for one face only.

d)  When two faces of wall are pointed with different pointing or if one face is plastered and other is pointed or plastered, deduction shall be made from the plaster or pointing on the side of frames for doors, windows, etc. on which the width of the reveal is less than that on the other side, but no deduction shall be made from the other side.

e)  Where width of reveals on both faces of wall is equal, deduction of 50% of area of opening on each face shall be made from area of pointing or plaster as the case may be.

f)  For opening having door frame equal to or projecting beyond thickness of wall, full deduction for opening shall be made from each pointed face of wall.

In case of openings of area above 3 sqm each, deduction shall be made for the openings, but jambs, soffits and sills shall be measured.

The following shall be measured separately.

a)  Raking out joints for old work only shall be measured and given in square meters

b) Raking out joints of old work built in mud mortar, lime mortar and cement mortar shall each be measured separately.

c) Raking out joints of different types of old walls, floors etc. shall each be measured separately.

d)  Raking single detached joints as for flashing old work shall be given in running meters.

Rate - The rate shall include the cost of all materials and labour involved in all the operations described above.

15.25. SPECIFICATIONS FOR WHITE WASHING WITH LIME

Scaffolding

15.25.1.1. Wherever scaffolding is necessary, it shall be erected on double supports tied together by horizontal pieces, over which scaffolding planks shall be fixed. No ballies, bamboos or planks shall rest or touch the surface which is being white washed.

15.25.1.2. For all exposed brick work or tile work double scaffolding having two sets of vertical supports shall be provided. The supports shall be sound and strong, tied together with horizontal pieces over which scaffolding planks shall be fixed.

Note: In case of special type of brick work, scaffolding shall be got approved from Engineer in advance.

15.25.1.3. Where ladders are used, pieces of all gunny bags shall be tied on their tops to avoid damage or scratches to walls.

15.25.1.4. For white washing the ceiling, proper scaffolding shall be erected.

15.25.2. Preparation of surface - Before new work is white washed, the surface shall be thoroughly brushed free from mortar droppings an foreign matter.

In case of old work, all loose particles and scales shall be scrapped off and holes in plaster as well as patches of less than 50 cm area shall be filled up with mortar of the same mix.  Where so specifically ordered by the Engineer, the entire surface of old white wash shall be thoroughly removed by scrapping and this shall be paid for separately where efflorescence is observed the deposits may be brushed clean and washed. The surface shall then be allowed to dry for at least 48 hours before white washing is done.

15.25.3. Preparation of lime wash

15.25.3.1. The lime wash shall be prepared from fresh stone white lime.  The lime shall be thoroughly slaked on the spot, mixed and stirred with sufficient water to make a thin cream. This shall be allowed to stand for a period of 24 hours and then shall be screened through a clean coarse cloth. 40 gm of gum dissolved in hot water, shall be added to each 10 cubic decimeter of the cream.  The approximate quantity of water to be added in making the cream will be 5 litres of water to one kg of lime.

Indigo (Neel) up to 3 gm per kg of lime dissolved in water, shall then be added and stirred well. Water shall then be added at the rate of about 5 litres per kg. of lime to produce a milky solution.

15.25.4. Application

15.25.4.1. The white wash shall be applied with brushes to the specified number of coats. The operation for each coat shall consist of a stroke of the brush given from the top downwards, another from the bottom upwards over the first stroke, and similarly one stroke horizontally from the right and another from the left before it dries.

15.25.4.2. Each coat shall be allowed to dry before the next one is applied.  Further each coat shall be inspected and approved by the Engineer before the subsequent coat is applied.  No portion of the surface shall be left out initially to be patched up later on.

15.25.4.3. For new work, three or more coats shall be applied till the surface presents a smooth and uniform finish through which the plaster does not show.  The finished dry surface shall not show any signs of cracking and peeling nor shall it come off readily on the hand when rubbed.

15.25.4.4. For old work, after the surface has been prepared as described, a coat of white wash shall be applied over the patches and repairs.  Then a single coat or two or more coats of white wash as stipulated in the description of the item shall be applied over the entire surface.  The white washed surface should present a uniform finish through which the plaster patches do not appear.  The washing on ceiling should be done prior to that on walls.

Note: In case of Hessian ceiling, on no account, lime shall be used as it rots cloth and Hessian.

15.25.5. Protective Measures - Doors, Windows, floors, articles of furniture etc. and such other parts of the building not to be white washed, shall be protected from being splashed upon.  Splashings and droppings, if any shall be removed by the contractor at his own cost and the surfaces cleaned. Damages if any to furniture or fittings and fixtures shall be recoverable from the contractor.

15.25.6. Measurements

15.25.6.1 Length and breadth shall be measured correct to a cm. and area shall be calculated in sqm correct to two places of decimals.

15.25.6.2 Measurements for jambs, Soffits, and Fills etc. for openings shall be as described.

15.25.6.3 Corrugated surfaces shall be measured flat as fixed and the area so measured shall be increased by the following percentages to allow for the girthed area.

Corrugated asbestos cement sheet - 20%

Semi corrugated asbestos cement sheet -10%

15.25.6.4. Cornices and other such wall or ceiling features, shall be measured along the girth and included in the measurements.

15.25.6.5. The number of coats of each treatment shall be stated. The item shall include removing nails, making good holes, cracks, patches etc. not exceeding 50 sq. cm. each with material similar in composition to the surface to be prepared.

15.25.6.6. Work on old treated surfaces shall be measured separately and so described.

15.26. SPECIFICATIONS FOR LIME WASHING

Lime wash shall be used as a base coat where so specified.   The specifications for ‘white washing with lime’ shall apply except that quality lime shall be used and the wash will be mixed to a thicker consistency.  The other details and specifications described in 15.25 will apply in toot.

15.27. SPECIFICATIONS FOR WHITE WASHING WITH WHITING

15.27.1. Preparation of Mix - Whiting (ground white chalk) shall be dissolved in sufficient quantity of warm water and thoroughly stirred to form thin slurry which shall then be screened through a clean coarse cloth.  Two kg of gum and 0.4 kg of copper sulphate dissolved separately in hot water shall be added for every cum of the slurry which shall then be diluted with water to the consistency of milk so as to make a wash ready for use.

15.27.2. Other specifications described shall apply in this case also.

15.28. SPECIFICATIONS FOR COLOUR WASHING

15.28.1 The mineral colours, not affected by lime, shall be added to white wash. Indigo (Neel) shall however, not be added. No colour wash shall be done until a sample of the colour wash of the required tint or shade has been got approved from the engineer.  The colour shall be of even tint or shade over the whole surface.  If it is blotchy or otherwise badly applied, it shall be redone by the contractor.

For new work, the priming coat shall be of white wash with lime or with whiting as specified in the description of the item.  Two or more coats shall then be applied on the entire surface till it represents a smooth and uniform finish.

For old work, after the surface has been prepared as described a coat of colour wash shall be applied over the patches and repairs.  Then a single coat or two or more coats of colour wash, as stipulated in the description of the item shall be applied over the entire surface. The colour washed surface shall present a uniform finish.

The finished dry surface shall not be powdery and shall not readily come off on the hand when rubbed.

Other specifications as described under 15.25 

15.29. SPECIFICATIONS FOR DRY DISTEMPERING

15.29.1. Materials -  Dry distemper of required colour (IS-427) and of approved brand and manufacture shall be used.  The shade shall be got approved from the Engineer before application of the distemper.  The dry distemper colour as required shall be stirred slowly in clean water using 6 decilitres (0.6 litre) of water per kg of distemper or as specified by the makers.  Warm water shall preferably be used. It shall be allowed to stand for at least 30 minutes (or if practicable over night) before use. The mixture shall be well stirred before and during use to maintain an even consistency.

Distemper shall not be mixed in larger quantity than is actually required for one day’s work.

15.29.2. Preparation of Surface

15.29.2.1. Before new work is distempered, the surface shall be thoroughly brushed free from mortar droppings and other foreign matter and sand papered smooth.

15.29.2.2. New plastered surfaces shall be allowed to dry for at least two months, before applying distemper.

15.29.2.3. In the case of old work, all those pieces and scales shall be removed by sand papering.  The surface shall be cleaned of all grease, dirt, etc.

15.29.2.4. Pitting in plaster shall be made good with Plaster of Paris mixed with the colour to be used. The surface shall then be rubbed down again with a fine grade sand paper and made smooth.  A coat of the distemper shall be applied over the patches. The patched surface shall be allowed to dry thoroughly before the regular coat of distemper is applied.

15.29.3. Priming Coat - A priming coat of whiting shall be applied over the prepared surface in case of new work, if so stipulated in the description of the item.  No white washing coat shall be used as a priming coat for distemper.

The treated surface is allowed to dry before distemper coat is given.

15.29.4. Application

15.29.4.1 In the case of new work, the treatment shall consist of a priming coat of whiting followed by the application of two or more coats of distemper till the surface attains an even colour.

15.29.4.2 For old work, the surface prepared as described shall be applied one or more coats of distemper till the surface attains an even colour.

15.29.4.3. The application of each coat shall be as follows - The entire surface shall be coated with the mixture uniformly, with proper distemper brushes (ordinary white wash brushed shall not be allowed) in horizontal strokes followed immediately by vertical ones which together shall constitute one coat.

15.29.4.4. The subsequent coats shall be applied only after the previous coat has dried.

15.29.4.5. The finished surface shall be even and uniform and shall show no brush marks.

15.29.4.6. Enough distemper shall be mixed to finish one room at a time. The application of a coat in each room shall be finished in one operation and no work shall be started in any room, which cannot be completed the same day.

15.29.4.7. After each day’s work, the brushes shall be washed in hot water and hung down to dry.  Old brushes which are dirty or caked with distemper shall not be used.

15.29.5. The specifications in respect of scaffolding, protective measures, measurements and rate shall be as described.

15.30. SPECIFICATIONS FOR OIL EMULSION (OIL BOUND) WASHABLE DISTEMPERING

15.30.1. Materials -  Oil emulsion (Oil Bound) washable distemper (IS-428) of approved brand and manufacture shall be used. The primer where used as on new work shall be cements primer or distemper primer as described in the item.  These shall be of the same manufacture as distemper.  The distemper shall be diluted with water or any other prescribed thinner in a manner recommended by the manufacturer.  Only sufficient quantity of distemper required for day’s work shall be prepared.

The distemper and primer shall be brought by the contractor in sealed tins in sufficient quantities at a time to suffice for a fortnight’s work, and the same shall be kept in the joint custody of the contractor and the Engineer.  The empty tins shall not be removed from the site of work, till this item of work has been completed and passed by the Engineer.

15.30.2. Preparation of the Surface

15.30.2.1. For new work the surface shall be thoroughly cleaned of dust, old white or colour wash by washing and scrubbing. The surface shall then be allowed to dry for at least 48 hours. It shall then be sand papered to give a smooth and even surface. Any unevenness shall be made good by applying putty, made of plaster of pairs mixed with water on the entire surface including filling up the undulations and then sand papering the same after it is dry.

15.30.2.2 In the case of old work, all loose pieces and scales shall be removed by sand papering. The surface shall be cleaned of all grease dirt etc.

Pitting in plaster shall be made good with plaster of paris mixed with the colour to be used.  The surface shall then be rubbed down again with a fine grade sand paper and made smooth.  A coat of the distemper shall be applied over the patches. The patched surface shall be allowed to dry thoroughly before the regular coat of distemper is applied.

15.30.3. Application

15.30.3.1. Priming Coat - The priming coat shall be with distemper primer or cement primer, as required in the description of the item.  The application of the distemper primer shall be as described.

Note: If the wall surface plaster has not dried completely, cement primer shall be applied before distempering the walls. But if distempering is done after the wall surface is dried completely, distemper primer shall be applied.

Oil bound distemper is not recommended to be applied, within six months of the completion of wall plaster. However, newly plastered surfaces if required to be distempered before a period of six months shall be given a coat of alkali resistant priming coat conforming to IS - 109 and allowed to dry for at least 48 hours before distempering is commenced.

For old work no primer coat is necessary.

15.30.3.2. Distemper Coat - For new work, after the primer coat has dried for at least 48 hours, the surface shall be lightly sand papered to make it smooth for receiving the distemper, taking care not to rub out the priming coat.  All loose particles shall be dusted off after rubbing.  One coat of distemper properly diluted with thinner (water or other liquid as stipulated by the manufacturer) shall be applied with brushes in horizontal strokes followed immediately by vertical ones which together constitute one coat.

The subsequent coats shall be applied in the same way.  Two or more coats of distemper as are found necessary shall be applied over the primer coat to obtain an even shade.

A time interval of at least 24 hours shall be allowed between successive coats to permit proper drying of the preceding coat.

For old work the distemper shall be applied over the prepared surface in the same manner as in new work.  One or more coats of distemper as are found necessary shall be applied to obtain an even and uniform shade. 15 cm double bristled distemper brushes shall be used.  After each days work, brushes shall be thoroughly washed in hot water with soap solution and caked with distemper shall not be used on the work.

15.30.4. The specifications in respect of scaffolding, protective measures and measurements shall be as described.

15.30.5. Rate - The rate shall include the cost of all labour and materials involved in all the above operations (including priming coat) described above.

15.31. SPECIFICATIONS FOR CEMENT PRIMER COAT

15.31.0. Cement primer coat is used as a base coat on wall finish of cement, lime or lime cement plaster or on asbestos cement surfaces before oil emulsion distemper paints are applied on them.  The cement primers is composed of a medium and pigment which are resistant to the alkalis present in the cement, lime or lime cement in wall finish and provides a barrier for the protection of subsequent coats of oil emulsion distemper paints.

Primer coat shall be preferably applied by brushing and not by spraying.  Hurried priming shall be avoided particularly on absorbent surfaces.  New plaster patches in old work should also be treated with cement primer before applying oil emulsion paints etc.

15.31.1. Preparation of the surface:  The surface shall be thoroughly cleaned of dust, old white or colour wash by washing and scrubbing. The surface shall then be allowed to dry for at least 48 hours. It shall then be sand papered to give a smooth and even surface. Any unevenness shall be made good by applying putty, made of Plaster of Paris mixed with water on the entire surface including filling up the undulations and then sand papering the same after it is dry.

15.31.2. Application:  The cement primer shall be applied with a brush on the clean dry and smooth surface. Horizontal strokes shall be applied immediately afterwards. This entire operation will constitute one coat.  The surface shall be finished as uniformly as possible leaving no brush marks.  It shall be allowed to dry for at least 48 hours, before oil emulsion paint is applied.

The specifications in respect of scaffolding, protective measures, measurements and rate shall be as described under 15.25

15.32. SPECIFICATIONS FOR CEMENT PAINT

15.32.1. Material - The cement paint shall be (conforming to IS: 5410) of approved brand and manufacture.

The cement paint shall be brought to the site of work by the contractor in its original containers is sealed condition.  The material shall be brought in at a time in adequate quantities to suffice for the whole work or at least a fortnight’s work. The materials shall be kept in the joint custody of the contractor and the engineer.  The empties shall not be removed from the site of work till the relevant item of work has been completed and permission obtained from the engineer.

15.32.2. Preparation of surface - For new work, the surface shall be thoroughly cleaned of all mortar dropping, dirt dust, algae grease and other foreign matter by brushing and washing.  Pitting in plaster shall be made good and a coat of water proof cement paint shall be applied over patches after wetting them thoroughly.

15.32.3. Preparation of mix - Cement paint shall be mixed in such quantities as can be used up within an hour of its mixing as otherwise the mixture will set and thicken, affecting flow and finish. Cement paint shall be mixed with water in two stages.  The first stage shall comprise of 2 parts of cement paint of one part of water stirred thoroughly and allowed to stand for 5 minutes. Care shall be taken to add the cement paint gradually to the water and not vice versa.  The second stage shall comprise of adding further one part of water to the mix and stirring thoroughly to obtain a liquid of workable and uniform consistency.  In all cases the manufacturer’s instructions shall be followed meticulously.

The lids of cement paint drums shall be kept tightly closed when not in use, as by exposure to atmosphere the cement paint rapidly becomes air set due to its hygroscopic qualities.

In case of cement paint brought in gunny bags, once the bag is opened, the contents should be consumed in full on the day of its opening.  If the same is not likely to be consumed in full, the balance quantity should be transferred and preserved in an airtight container to avoid its exposure to atmosphere.

15.32.4. Application

15.32.4.1. The solution shall be applied on the clean and wetted surface with brushes or spraying machine.  The solution shall be kept well stirred during the period of application.  It shall be applied on the surface which is on the shady side of the building so that the direct heat of the sun on the surface is avoided. The method of application of cement paint shall be as per manufacturer’s specification.  The completed surface shall be watered after the day’s work.

15.32.4.2.  The second coat shall be applied after the first coat has been set for at least 24 hours. Before application of the second or subsequent coats, the surface of the previous coat shall not be wetted.

15.32.4.3. For new work, the surface shall be treated with three or more coats of water proof cement paint as found necessary to get a uniform shade.

15.32.4.4. For old work, the treatment shall be with one or more coats as found necessary to get a uniform shade.

15.32.5. Precaution - Water proof cement paint shall not be applied on surfaces already treated with white wash, colour wash, distemper dry or oil bound, varnishes, paints etc.  It shall not be applied on gypsums, would and metal surfaces.

15.32.6. The specifications in respect of scaffolding, protective measures, measurements and rate shall be as described in 15.25.  The coefficient for cement paint on RCC jalli shall be the same as provided in Sl. No. 7 of Table 1 under para 15.33.6.4 for painting trellis work.

15.33. SPECIFICATIONS FOR PAINTING

15.33.1. Materials -  Paints, oils, varnishes etc. of approved brand and manufacture shall be used. Only ready mixed paint (Exterior grade) as received from the manufacturer without any admixture shall be used.

If for any reason, thinning is necessary in case of ready mixed paint the brand of thinner recommended by the manufacturer or as instructed by the Engineer shall be used.

Approved paints, oil or varnishes shall be brought to the site of work by the contractor in their original containers in sealed condition.  The material shall be brought in at a time in adequate quantities to suffice for the whole work or at least a fortnight’s work.  The materials shall be kept in the joint custody of the contractor and the engineer.  The empties shall not be removed from the site of work, till the relevant item of work has been completed and permission obtained from the engineer.

15.33.2. Commencing Work - Painting shall not be started until the engineer has inspected the items of work to be painted, satisfied himself about their proper quality and given his approval to commence the painting work.  Painting of external surface should not be done in adverse weather condition like hail storm and dust storm.

Painting, except the priming coat, shall generally be taken in hand after practically finishing all other building work.

The rooms should be thoroughly swept out and the entire building cleaned up, at least one day in advance of the paint work being started.

15.33.3. Preparation of Surface - The surface shall be thoroughly cleaned and dusted off.  All rust, dirt, scales, smoke splashes, mortar droppings and grease shall the thoroughly removed before painting is started. The prepared surface shall have received the approval of the engineer after inspection, before painting is commenced.

15.33.4. Application

15.33.4.1. Before pouring into smaller containers for use, the paint shall be stirred thoroughly in its containers, when applying also, the paint shall be continuously stirred in the smaller containers so that its consistency is kept uniform.

15.33.4.2. The painting shall be laid on evenly and smoothly by means of crossing and laying off, the latter in the direction of the grains of wood.  The crossing and laying off consists of covering the area over the paint, brushing the surface hard for the first time over and then brushing alternately in opposite direction, two or three times and then finally brushing lightly in a direction at right angles to the same. In this process, no brush marks shall be left after the laying off is finished. The full process of crossing and lying off will constitute one coat.

15.33.4.3. Where so stipulated, the painting shall be done by spraying.  Spray machine used be (a) high pressure (small air aperture) type, or (b) a low pressure (large air gap) type, depending on the nature and location of work to be carried out.  Skilled and experienced workmen shall be employed to the requisite consistency by adding a suitable thinner.

15.33.4.4. Spraying should be done only when dry condition prevails.  Each coat shall be allowed to dry out thoroughly and rubbed smooth before the next-coat is applied. This should be facilitated by thorough ventilation.  Each one except the last coat, shall be lightly rubbed down with sand paper or fine pumice stone and cleaned off dust before the next coat is laid.

15.33.4.5. No left over paint shall be put back into the stock tins.  When not in use, the containers shall be kept properly closed.

15.33.4.6. No hair marks from the brush or clogging of paint puddles in the corners of panels, angles of moldings etc.  shall be left on the work.

15.33.4.7. In painting doors and windows, the putty round the glass panes must also be painted but care must be taken to see that no paint stains etc. are left on the glass.  Tops of shutters and surfaces in similar hidden locations shall not be left out in painting.  However, bottom edge of the shutters where the painting is not practically possible, need not be done nor any deduction on this account will be done but two coats of primer of approved make shall be done on the bottom edge before fixing the shutters.

15.33.4.8. On painting steel work, special care shall be taken while painting over bolts, nuts, rivets overlaps etc.

14.33.4.9. The additional specifications for primer and other coats of paints shall be as according to the detailed specifications under the respective headings.

15.33.5. Brushes and containers - After work, the brushes shall be completely cleaned of paint and linseed oil by rinsing with turpentine.  A brush in which paint has dried up is ruined and shall on no account be used for painting work.  The containers when not in use shall be kept closed and free from air so that paint does not thicken and also shall be kept safe from dust.  When the paint has been used, the containers shall be washed with turpentine and wiped dry with soft clean cloth, so that they are clean, and can be used again.

15.33.6. Measurements

15.33.6.1. The length and breadth shall be measured correct to a cm. The area shall be calculated in sqm (correct to two places of decimal), except otherwise stated.

15.33.6.2. Small articles not exceeding 10 sq. decimeter (0.1 sqm) of painted surfaces where not in conjunction with similar painted work shall be enumerated.

15.33.6.3. Painting up to 10 cm in width or in girth and not in conjunction with similar painted work shall be given in running meters and shall include cutting to line where so required.

Note: Components of trusses, compound girders, stanchions, lattices and similar work shall, however, be given in sq. meters irrespective of the size or girth of members.  Priming coat of painting shall be included in the work of fabrication.

15.33.6.4. In measuring painting, varnishing, oiling etc. of joinery and steel work etc. The coefficients as indicated in following tables shall be used to obtain the area payable. The coefficients shall be applied to the areas measured flat and not girthed.

Table 1 Equivalent plain areas of uneven surface

Sl. No.

Description of work

How measured

Multiplying  coefficients

1

2

3

4

I.

Wood work doors, windows etc.

1

Panelled or framed and braced doors, windows etc.    

Measured flat (not girthed including)

1.30 (for each side)

2

Ledged and battened or ledged, battened and braced doors, windows etc.                  

Frame, edges chocks, cleats, etc. shall be deemed to be included in the item.

 

3

Flush doors etc.           

- do -   

1.20 (for each side)

4

Part panelled and part glazed or gauzed doors, windows etc. (Excluding painting of wire gauze portion)

- do -   

1.00 (for each side)

5

Fully glazed or gauged doors, windows etc. (Excluding painting of wire gauze portion)

           

- do -   

0.80 (for each side)

6

Fully venetianed or louvered doors,

- do -   

1.80 (for each windows etc. side)

7

Trellis work one way or two way

Measured flat overall, no deduction shall be made for open spaces, suppor ting members shall not be measured separately

2 ( for pain- ting all over)

8

Carved or enriched work           

Measured flat

2 ( for each side)

9

Weather boarding         

Measured flat (not girthed supporting frame work shall not be measured separately)

1.20 (for each side)

10

Wood shingle roofing   

Measured flat (not girthed)           

1.10 (for each side)

11

Boarding with cover fillets and

Measured flat (not girthed)           

1.05 (for each match boarding side)

12

Tile and slate battening

Measured flat overall no deductions shall be made for open spaces

0.80 (for painting all over)

II.

Steel Work Doors, Windows, etc.

13

Plain sheeted steel doors or windows

Measured flat (not girthed including frame edges etc.)

1.10 (for each side)

14

Fully glazed or gauzed steel doors and windows (excluding painting of wire gauze portion)

 

- do -   

0.50 (for each side)

 

Partly panelled and partly glazed doors and windows (excluding painting of wire gauze portion)

 

- do -

0.80 (for each side)

16

Corrugated sheeted steel doors or windows          

- do -   

1.25 (for each side)

17

Collapsible gates

Measured flat   

1.50 (for painting all over)

18

Rolling shutters of interlocked laths

Measured flat (size of            opening) all over ; jamb guides, bottom rails and locking arrangement etc. shall be included in the item (top cover shall be measured separately)

1.10 (for each side)

III.

General

19

Expanded metal,  hard drawn steel Wire fabric  of approved quality, grill works and gratings in guard Bars, balustrades, railing partitions and MS bars in windows frames

Measured flat overall, no deduction shall be made for open spaces; supporting members shall not be measured separately.

1 (for paint all over)

 

Open palisade fencing and gates inclu ding standards, braces, rails stays etc. in timber or steel.

- do -    (see note No. 12)           

1 (for paint all over)

 

Corrugated iron sheeting in roofs, side cladding etc.

- do – Measured flat (not girthed)

1.14 (for each side)

 

AC semi-corrugated  sheeting in roofs, side cladding etc.         

- do -   

1.20 (for each side)

 

AC semi-corrugated sheeting in roofs, side cladding etc. or  Nainital pattern using plain sheets

- do -

1.10 (for each side)

 

Wire gauze shutters including painting of wire gauze.  

- do-    

1.00 (for each side)

Explanatory notes for Table 1:

1)  Measurements for doors windows etc., shall be taken flat (and not girthed) over all including frames, where provided. Where frames are not provided, the shutter measurements shall be taken.

2)  Where doors, windows, etc., are of composite types other than those included in Table 1 the different portion shall be measured separately with their appropriate coefficients, the centre line of the common rail being taken as the dividing line between the two portions.

3)  The coefficients for door and windows shall apply irrespective of the size of frames and shutter members.

4)  In case steel frames are used the area of doors, windows shutters shall be measured flat excluding frames.

5)  When the two faces of a door, window etc. are to be treated with different specified finishes, measurable under separate items, the edges of frames and shutters shall be treated with the one or the other type of finish as ordered by the Engineer and measurement of this will be deemed to be included in the measurement of the face treated with that finish.

6)  In the case where shutters are fixed on both faces of the frames, the measurement for the door frame and shutter on one face shall be taken in the manner already described, while the additional shutter on the other face will be measured for the shutter only excluding the frame.

7)  Where shutters are provided with clearance at top or / and bottom each exceeding 15 cm height, such openings shall be deducted from the overall measurements and relevant coefficient shall be applied to obtain the area payable.

8) Collapsible gates shall be measured for width from outside to outside of gate in its expanded position and for height from bottom to top of channel verticals. No separate measurements shall be taken for the top and bottom guide rails rollers, fittings etc.

9)  Coefficients for sliding doors shall be the same as for normal types of doors in the table. Measurements shall be taken outside to outside of shutters, and no separate measurements shall be taken for the painting guide rails, rollers, fittings, etc.

10)   Measurements of painting as above shall be deemed to include painting all iron fittings in the same or different shade for which no extra will be paid.

11)  The measurements of guard bars, expanded metal, hard drawn steel wire fabric of approved quality, grill work and gratings, when fixed in frame work, painting of which is once measured else where shall be taken exclusive of the frames. In other cases the measurements shall be taken inclusive of the frames.

12)  For painting open palisade fencing and gates etc., the height shall be measured from the bottom of the lowest rail, if the palisades do not go below it, (or from the lower end of the palisades, if they project below the lowest rail), up to the top of rails or palisades whichever are higher, but not up to the top of standards when the latter are higher than the top rails or the palisades.

15.33.6.5. Width of moulded work of all other kinds, as in hand rails, cornices, architraves shall be measured by girth.

15.33.6.6. For trusses, compound girders, stanchions, lattice girders, and similar work, actual areas shall be measured in sq. meters and no extra shall be paid for painting on bolt heads, nuts, washers etc. even when they are picked out in a different tint to the adjacent work.

15.33.6.7. Painting of rain water, soil, waste, vent and water pipes etc. shall be measured in running metres of the particular diameter of the pipe concerned. Painting of specials such as bends, heads, branches, junctions, shoes, etc. shall be included in the length and no separate measurements shall be taken for those or for painting brackets, clamps etc.

15.33.6.8. Measurements of wall surfaces and wood and other work not referred to already shall be recorded as per actual.

15.33.6.9. Flag staffs, steel chimneys, aerial masts, spires and other each objects requiring special scaffolding shall be measured separately.

15.33.7. Precautions - All furnitures fixtures, glazing, floors, etc. shall be protected by covering and stains, smears, splashings, if any shall be removed and any damages done shall be made good by the contractor at his cost.

15.33.8. Rate - Rates shall include cost of all labour and materials involved in all the operations described above and in the particular specifications given under the several items.

15.34. SPECIFICATIONS FOR PAINTING PRIMING COAT ON WOOD, IRON OR PLASTERED SURFACES

15.34.1. Primer

15.34.1.1. The primer for wood work, iron work or plastered surface shall be as specified in the description of item.

15.34.1.2. Primer for plaster / wood work/ Iron & Steel / Aluminium surfaces shall be as specified below:

S. No.

Surfaces          

Primer to be used

1

Wood work (hard and soft wood)          

Pink conforming to IS: 3536

2

Resinour wood and plywood

Aluminium primer conforming to IS: 3585

3

(A)  Aluminium and light alloys

Zinc chromate primer conforming to IS: 104

 

(B)  Iron, Steel and Galvanized steel      

Red Oxide Zinc chromate Primer conforming to IS: 2074

4

Cement / Concrete / RCC / Brick work, Plastered surfaces, asbestos surfaces to receive Oil bound distemper or paint finish   

Cement primer conforming to IS: 109

15.34.1.3. The primer shall be ready mixed primer of approved brand and manufacture.

15.34.1.4. Where primer for wood work is specified to be mixed at site, it shall be prepared from a mixture of red lead, white lead and double boiled linseed oil in the ratio of 0.7 kg: 0.7 kg: 1 litre.

15.34.1.5. Where primer for steel work is specified to be mixed at site, it shall be prepared from a mixture of red lead, raw linseed oil and turpentine in the ratio of 2.8 kg: 1 litre: 1 litre.

15.34.1.6. The specifications for the base vehicle and thinner for mixed on site primer shall be as follows:

a)  White lead -  The White lead shall be pure and free from adulterants like barium sulphate and whiting. It shall conform to IS: 103-1962

b)  Red lead - This shall be in powder form and shall be pure and free from adulterants like brick dust etc. It shall conform to IS: 102-1962

c)  Raw linseed oil - Raw linseed oil shall be lightly viscous but clear and of yellowish colour with light brown tinge. Its specific gravity at a temperature of 30 degree C shall be between 0.923 and 0.928.

Note - The oil shall be mellow and sweet to the taste with very little smell.  The oil shall be of sufficiently matured quality. Oil turbid or thick, with acid and bitter taste and rancid odour and which remains sticky for a considerable time shall be rejected. The oil shall conform in all respects to IS: 75-1973.  The oil shall be of approved brand and manufacture.

d)  Double boiled linseed oil - This shall be more viscous than the raw oil, have a deeper colour and specific and specific gravity between 0.931 and 0.945 at a temperature of 30 degree C.  It shall dry with a glossy surface. It shall confirm in all respects to IS: 77-1976.  The oil shall be of approved brand and manufacture.

e) Turpentine: Mineral turpentine i.e., petroleum distillate which has the same rate of evaporation as vegetable turpentine shall be used. It shall have no grease or other residue when allowed to evaporate. It shall conform to IS: 533-1998

15.34.1.7. All the above materials shall be of approved manufacture and brought to site in their original packing in sealed condition.

15.34.2. Preparation of Surface 

15.34.2.1. Wooden Surface:   The wood work to be printed shall be dry and free from moisture.

The surface shall be thoroughly cleaned.  All unevenness shall be rubbed down smooth with sand paper and shall be well dusted. Knots if any, shall be covered with preparation of red lead made by grinding red lead in water and mixing with strong glue sized and used hot.  Appropriate filler material conforming to IS: 345-1952 with same shade as paint shall be used where specified.  The surface treated for knotting shall be dry before paint is applied. After obtaining approval of engineer for wood work, the priming coat shall be applied before the wood work is fixed in position.  After the priming coat is applied, the holes and indentation on the surface shall be stopped with glazier’s putty or wood putty respectively.  Stopping shall not be done before the priming coat is applied as the wood will absorb the oil in stopping and the latter is therefore liable to crack.

15.34.2.2. Iron & Steel Surface - All rust and scales shall be removed by scrapping or by brushing with steel wire brushes. Hard skin of oxide formed on the surface of wrought iron during rolling which becomes loose by rusting, shall be removed.

All dust and dirt shall be thoroughly wiped away from the surface.

If the surface is wet, it shall be dried before priming coat is undertaken.

Plastered Surface - The surface shall ordinarily not be painted until it has dried completely.  Trial patches of primer shall be laid at intervals and where drying is satisfactory, painting shall then be taken in hand.  Before primer is applied, holes and undulations shall be filled up with plaster of paris and rubbed smooth.

15.34.2.3. Application - The primer shall be applied with brushes, worked well into the surface and spread even and smooth.  The painting shall be done by crossing and laying off as described in 15.33.4

15.34.4. SPECIFICATIONS FOR TREATMENT ON STEEL FOR AGGRESSIVE ENVIRONMENT

15.34.4.1. A second coat of ready mixed red oxide zinc chromate primer may be applied where considered necessary in aggressive environment such as near Industrial establishment and coastal regions where the steel members are prone to corrosion.  The second coat (which shall be paid for separately) is to be applied after placing the member in position and just before applying paint.  The second coat of primer is not necessary in case of painting with synthetic enamel paint as it is applied over an under coat of ordinary paint.

15.34.4.2 The specifications described under 15.33 shall hold good so far as they are applicable.

15.35. SPECIFICATIONS FOR PAINTING WITH READY MIXED PAINT

Ready mixed paints of approved brand and manufacture and of the required shades shall be used.  They shall conform in all respects to the relevant IS Specifications.

15.35.1. Painting on new surface - The surface which has not been painted earlier, or the paint had been removed by paint remover, burning, caustic soda etc., shall be considered to be new surface.

15.35.1.1. Preparation of surface

a)  Wood work - The surface shall be cleaned and all unevenness removed as specified knots if visible, shall be covered with a preparation of red lead. Holes and indentations on the surface shall be filled in with glazier’s putty or wood putty conforming to IS: 419 and rubbed smooth before painting is done.  The surface should be thoroughly dry before painting.

b)  Iron and steel work - The priming coat shall have dried up completely before painting is started. Rust and scaling shall be carefully removed by scraping or by brushing with steel wire brushes. All dust and dirt shall be carefully and thoroughly wiped away.

c)  Plastered surface - The priming coat shall have dried up completely before painting is started.  All dust or dirt that has settled on the priming coat shall be thoroughly wiped away before painting is started.

15.35.1.2. Application - The specifications described shall hold good as far as applicable. The number of coats to be applied will be stipulated in the item.  The painted surface shall present a uniform appearances and glossy finish, free from streaks, blisters etc.

15.35.1.3. The specifications described in 15.33 shall hold good in so far as they are applicable.

15.35.2. SPECIFICATION FOR PAINTING ON OLD SURFACE

The surface which has been painted earlier shall be considered.

15.35.2.1. Preparation of Surface

a)  Wood work - If the old paint is sound and firm and its removal is considered unnecessary, the surface shall be rubbed down with pumice stone after it has been cleaned of all smoke and grease by washing with lime and rinsing with water and drying.  All dust and loose paint shall be completely removed. The surface shall then be washed with soap and water.

If the old painted surface is blistered or flaked badly old paint shall be completely removed as described and such removal shall be paid for separately. Holes and cracks if any shall be stopped with glazier’s putty or wood putty conforming to IS: 419-1967.  Further the painting itself shall be treated as on new surface and paid for, accordingly.

b)  Iron and steel work -  If the old paint is sound and firm and its removal is considered unnecessary, it shall be rubbed with wire brushes and any loosened paint taken off.  All dust shall then be thoroughly wiped away. The surface shall then be wiped finally with mineral turpentine to remove grease and perspiration of hand marks etc. and then allowed to dry.

If the old painted surface is in bad condition and blistered and flaked, the old paint shall be completely removed and the surface prepared, as described.  Such removal shall be paid for separately. The painting including the priming coat shall be treated as on nee work and paid for accordingly.

c)  Plastered surface - It shall be as specified for wood work.  If before painting any portion of the wall shows signs of dampness, the causes shall be investigated and the damp surface shall be properly treated. Such treatment shall be paid for separately.  A thin coat of white lead if so required shall be applied on the wet or patchy portion of the surface before painting is undertaken and this shall be paid extra.

15.35.2.2. Application - The specifications as described shall hold good as far as possible.  The number of coats to be given shall be as stipulated in the description of the item.

The specifications described 15.3.3 shall hold good in so far as they are applicable.

15.36. Specifications for Painting Ready Mixed Paint Over G. S. Sheets

Ready mixed paint, suitable for painting over G. S. sheets, of approved and manufacture and of the required shade shall be used. New or weathered G. S. sheets shall be painted with a priming coat of one coat of red oxide zinc chromate paint.  Primer shall be applied before fixing sheets in place.

15.36.1. Preparation of surface

15.36.1.1. Painting new surface - The painting of new G. S. sheets shall not usually be done till the sheets have weathered for about a year. When new sheets are to be painted before they have weathered they shall be treated with a mordant solution prepared by mixing 38 gm of copper acetate in a litre of soft water or 13 gm hydrochloric acid in a solution of 13 gm each of copper chloride, copper nitrate and ammonium chloride dissolved in a litre of soft water.  This quantity of solution is sufficient for about 235 sqm. to 280 sqm of area and is applied for ensuring proper adhesion of paint. The painting with the mordant solution will be paid for separately.

Before painting on new or weathered G. S. sheets, rust particles shall be completely cleaned with coarse emery paper and brush.  All grease marks shall also be removed and the surface washed and dried and rusted surface shall be touched with ready mixed paint of red lead.

15.36.1.2. Painting old surface - If the old paint is firm and sound, it shall be cleaned of grease, smoke etc. The surface shall then be rubbed down with sand paper and dusted. Rusty patches shall be cleaned up and touched with red lead.

If the old paint is blistered and flaked, it shall be completely removed as described.  Such removal shall be paid for separately and painting shall be treated as on new work.

15.36.2. Application - The number of coats to be applied shall be as in the description shall be as in the description of item.  In the case of C. G. S. sheets, the crowns of the corrugations shall be painted first and when these get dried the general coat shall be given to ensure uniform finish over the entire surface without the crowns showing signs of thinning.

The second or additional coats shall be applied when the previous coat has dried.

The specifications described in 15.33 shall hold good so far as they are applicable.

15.37. SPECIFICATIONS FOR PAINTING CAST IRON RAIN WATER, SOIL, WASTE AND VENT PIPES AND FITTINGS

15.37.1. The primer shall be prepared on site or shall be of approved brand and manufacture as specified in the item.

Paint shall be anti-corrosive bitumastic paint, aluminium or other type as specified in the description of the item.

15.37.2. Painting New Surface

15.37.2.1. Preparation of Surface - The surface shall be prepared for priming coat as described in 15.34.2.2.

15.37.2.2. Application - The number of coat of painting over the priming coat shall be as stipulated in the description of the item. The application of paint over priming coat shall be carried out as specified.

15.37.2.3. Measurements - Measurements will be taken over the finished line of pipe including specials etc. in running meters, correct to a cm.

Pipes of different diameters of bore shall be measured and paid for separately.

Specials and fittings such as holder bat clamps, plugs etc. will not be measured separately.

15.37.2.4. Rate - The rate shall include the cost of all materials and labour involved in all the operations described above, including painting of all specials and fittings.

15.37.2.5. Specifications described in 15.33 shall hold good as far as they are applicable.

15.37.3. Painting on old surface

15.37.3.1. The surface shall be prepared as specified in 15.35.2.1 (b)

15.37.3.2. The specifications for application shall be as described in 15.33.4

15.37.3.3. Measurements, rate and other details shall be as specified in 15.37.2

15.38. SPECIFICATIONS FOR PAINTING WITH WOOD PRESERVATIVE

15.38.1. Oil type wood preservative of specified quality and approved make, conforming to IS: 218 shall be used. Generally, it shall be creosote oil Type-1 or Anthracene oil.

15.38.2. Painting on new surface

15.38.2.1. Preparation of surface - Painting shall be done only when the surface is perfectly dry to permit of good absorption. All dirt, dust or other foreign matter shall be removed from the surface to be painted. All roughness shall be sand papered and cleaned.

15.38.2.2. Application - The preservative shall be applied liberally with a stout brush and not daubed with rages or cotton waste. It shall be applied with a pencil brush at the joints of the wood  work.  The first coat shall be allowed at least 24 hours to soak in before the second (the final) coat is applied. The second coat shall be applied in the same manner as the first coat. The excess of preservative which does not soak into the wood shall be wiped off with a clean dry piece of cloth.

15.38.2.3. The specifications described in 15.33 shall hold good in so far as they are applicable.

15.38.3. Painting on old surface - The work shall be done in the same manner as on new surface except that only one coat shall be done.

15.39. SPECIFICATIONS FOR COAL TARRING

15.39.1. Coal tar of approved manufacture conforming to IS: 290 shall be used. The tar, to every litre of which 200 gm of unslaked lime has been added, shall be heated till it begins to boil. It must then be taken off the fire and kerosene oil added to it slowly at the rate of one part of kerosene oil to six or more parts by volume  and stirred thoroughly.  The addition of lime is for preventing the tar from running.

15.39.2. Coal Tarring New Surface

15.39.2.1. Preparation of surface - This shall be done as specified except that sand papering is not necessary.  Where iron work is to be painted it shall be freed from scales and rust before painting.

15.39.2.2. Application - The mixture shall be applied as hot as possible with a brush. The second coat shall be applied only after the first coat has thoroughly dried up.  Where possible, the article to be tarred shall be dipped in the hot mixture for better results.  The quantity of tar to be used for the first or second coat shall be not less than 0.16 and 0.12 litre per sqm respectively.  Thinning with kerosene oil shall be suitably done to ensure this.

15.39.2.3. The specifications described in 15.33 shall hold good in all other respects, so far as they are applicable.

15.39.3. Coal tarring old Surface - The work shall be done in the same manner as specified except that only one coat using 0.12 litre per sqm area shall be done.

15.40. SPECIFICATIONS FOR SPRAY PAINTING WITH FLAT WALL PAINT ON NEW SURFACE

15.40.0 The work shall include a priming coat of ‘Distempering Primer’ or ‘Cement Primer’ as specified in the description of the item.  Flat wall paint shall normally be applied on walls 12 months after their completion, in which case Distemper primer will suffice. If the walls are to be painted, earlier, the primer coat shall consist of cement primer.

15.40.1. The primer and the flat wall paint shall be of approved brand and manufacture and of the required shade.

15.40.2. The surface shall be prepared as described in 15.31.1

15.40.3. Application

15.40.3.1. Primer coat - The specified primer shall be painted or sprayed over the surface in an even and uniform layer.

15.40.3.2. Painting coats - When the surface is dry, the spray painting with the wall paint in uniform and even layers will be done to the required number of coats. Each coat shall be allowed to dry overnight and lightly rubbed with very fine grade of sand paper and loose particles brushed off before the next coat is sprayed.

Spraying should be done only when dry condition prevails.  During spraying the spray gun shall be held perpendicular to the surface to be coated and shall be passed over the surface in a uniform sweeping motion.  Different air pressures and fan adjustment shall be tried so as to obtain the best application.  The Air pressure shall not be kept too high as otherwise the paint will fog up and will be wasted.

At the end of the job, the spray gun shall be cleaned thoroughly so as to be free from dirt.  Incorrect adjustments shall be set right, as otherwise they will result in variable spray patterns, runs, sags and uneven coats.

If after the final coat of wall paints, the surface obtained is not up to the mark, further one or more coats as required shall be given after rubbing down the surface and dusting off all loose particles to obtain a smooth and even finish.

If the primer or wall paint gets thickened during the application, it shall be thinned suitably with the thinner recommended by the manufacture.

Adequate ventilation shall be provided to disperse spray fumes.  Fitments and floor shall be protected from the spray.

15.40.4. The specifications described in 15.33 shall hold good for all other details as far as applicable.

15.41. SPECIFICATIONS FOR SPRAY PAINTING WITH FLAT PAINT ON OLD SURFACE

15.41.0. Where the old paint is in sound condition, renewal shall be carried out as described below, otherwise the old paint shall be completely stripped and spray painting shall be carried out as over new work.  Such removal shall be paid for separately.

15.41.1. The flat wall paint shall be of approved brand and manufacture and of required shade.

15.41.2. Preparation of surface - The surface shall be washed to remove dust and dirt.   A mild detergent solution like soap water shall be used for washing and the surface shall also be rubbed down lightly with abrasive paper when dry.  Any patches appearing on the surface shall first be touched up with a coat of paint.  These shall be allowed to dry and then rubbed down lightly.

15.41.3. Application -  The paint shall then be applied with spraying machine in uniform and even layer.  A second coat shall be applied if considered necessary by the engineer but only after the first coat is complete dry and hard.

Spraying should be done only when dry condition prevails.  During spraying the spray gun shall be held perpendicular to the surface to be coated and shall be passed over the surface in uniform sweeping motion.  Different air pressures and fan adjustment shall be tried so as to obtain the best application.  The Air pressure shall not be kept too high as otherwise the paint will fog up and will be wasted.   At the end of the job, the spray gun shall be cleaned thoroughly so as to be free from dirt.  Incorrect adjustments shall be set right, as otherwise they result in variable spray patterns, runs, sags and uneven coats.

15.41.4. The specifications described in 15.33 shall hold good for all other details, as far as they are applicable.

15.42. SPECIFICATIONS FOR WALL PAINTING WITH PLASTIC EMULSION PAINT

15.42.0. The plastic emulsion paint is not suitable for application on external, wood and iron surface and surfaces which are liable to heavy condensation.  These paints are to be used on internal surfaces except wooden and steel.

15.42.1. Plastic emulsion paint as per IS: 5411 of approved brand and manufacture and of the required shade shall be used.

15.42.2. Painting on new surface

15.42.2.1. The wall surface shall be prepared as specified in 15.33.3.

15.42.2.2. Application - The number of coats shall be as stipulated in the item.  The paint will be applied in the usual manner with brush, spray or roller.  The paint dries by evaporation of the water content and as soon as the water has evaporated the film gets hard and the next coat can be applied. The time of drying varies from one hour on absorbent surfaces to 2 to 3 hours on non-absorbent surfaces.

The thinning of emulsion is to be done with water and not with turpentine.  Thinning with water will be particularly required for the under coat which is applied on the absorbent surface.   The quantity of water to be added shall be as per manufacturer’s instructions.

The surface on finishing shall present a flat velvety smooth finish.  If necessary more coats will be applied till the surfaces presents a uniform appearance.

15.42.2.3. Precautions

a)  Old brushes if they are to be used with emulsion paints should be completely dried of turpentine or oil paints by washing in warm soap water. Brushes should be quickly washed in water immediately after use and kept immersed in water during break periods to prevent the paint from hardening on the brush.

b)  In the preparation of wall for plastic emulsion painting, no oil base putties shall be used in filling cracks, holes etc.

c)  Splashes on floors etc. shall be cleaned out without delay as they will be difficult to remove after hardening.

d)  Washing of surfaces treated with emulsion paints shall not be done within 3 or 4 weeks of application.

Other details shall be as specified as far as they are applicable.

15.42.3. Painting on old surface

15.42.3.1. Preparation of surface

This shall be done, generally as specified except that the surface before application of paint shall be flattened well to get the proper flat velvety finish after painting.

15.42.3.2. Application: The number of coats to be applied shall be as in description of item.

The application shall be as specified in 15.42.2.2 except that thinning with water shall not normally be required.

15.42.3.3 Other details shall be as specified in 15.33 as far as applicable.

15.43. SPECIFICATIONS FOR PAINTING WITH ENAMEL PAINT

15.43.1. Enamel paint (conforming to is: 2933) of approved brand and manufacture and of the required colour shall be used.

For the under coat, the paint of same quality but of shade to suit that of the top coat shall be used.

15.43.2. Preparation of surface and application shall be as specified under 15.35 for painting on new surfaces or old surfaces, as the case may be.

15.43.3. Other details shall be as specified in 15.33 as far as applicable.

15.44. SPECIFICATIONS FOR PAINTING WITH SYNTHETIC ENAMEL PAINT

15.44.1. Synthetic enamel paint (conforming to IS: 2932) of approved brand and manufacture and of the required colour shall be used for the top coat and an undercoat of ordinary paint of shade to match the top coat as recommended by the same manufacturer shall be used.

15.44.2. Painting on new surface

15.44.2.1 Preparation of surface shall be as specified in 15.35.1.1(a) and (b) as the case may be.

15.44.2.2. Application: The number of coats including the undercoat shall be as stipulated in the item.

a) Under coat: One coat of the specified ordinary paint of shade suited to the shade of the top coat, shall be applied and allowed to dry overnight.  It shall be rubbed next day with the finest grade of wet abrasive paper to ensure a smooth and even surface, free from brush marks and all loose particles dusted off.

b)  Top coat:  Top coats of synthetic enamel paint of desired shade shall be applied after the undercoat is thoroughly dry.  Additional finishing coats shall be applied if found necessary to ensure properly uniform glossy surface.

15.44.2.3.  Other details shall be as specified in 15.33 as far as they are applicable.

15.44.3. Painting on old surface

15.44.3.1. Preparation of surface - Where the existing paint is firm and sound it shall be cleaned of grease, smoke etc. and rubbed with sand paper to remove all loose particles dusted off. All patches and cracks shall then be treated with stopping and filler prepared with the specified paint.  The surface shall again be rubbed and made smooth and uniform.

If the old paint is blistered and flaked it will be necessary to completely remove the same as described in 15.54.  Such removal shall be paid for separately and the painting shall be treated as on new surface.

15.44.3.2. Painting - The number of coats as stipulated in the item shall be applied with synthetic enamel paint.  Each coat shall be allowed to dry and rubbed down smooth with very fine wet abrasive paper, to get an even glossy surface. If however, the surface is not satisfactory additional coats as required shall be applied to get correct finish.

15.44.3.3. Other details shall be specified in 15.33 as far as they are applicable.

15.45. SPECIFICATIONS FOR PAINTING WITH ALUMINIUM PAINT

15.45.1. Aluminium paint shall be (conforming to IS: 2339-1963) of approved brand and manufacture. The paint comes in compact dual container with the paste and the medium separately.

The two shall be mixed together to proper consistency before use.

15.45.2. Preparation of surface

15.45.2.1. Steel Work (New surfaces) - All rust and scales shall be removed by scrapping or brushing with steel wire brushes and then smoothened with sand paper. The surface shall be thoroughly cleaned of dust.

15.45.2.2. C.G.S. Sheets (New surfaces) - The preparation of surface shall be as specified in 15.36.1.1.

15.45.2.3. Steel work or C. G. S. sheets (Old surfaces) - The specifications shall be as described in 15.36.1.2.

15.45.3. Application - The number of coats to be applied shall be as given in the item.  Each coat shall be allowed to dry for 24 hours and lightly rubbed down with fine grade sand paper and dusted off before the next coat is applied. The finished surface shall present an even and uniform appearance.

As aluminium paste is likely to settle in the container, care shall be taken to frequently stir the paint during used.  Also the paint shall be applied and laid off quickly, as surface is otherwise not easily finished.

Other details shall be as specified in 15.33 as far as they are applicable.

15.46. SPECIFICATIONS FOR PAINTING WITH ACID PROOF PAINT

15.46.1. Acid proof paint of approved brand and manufacture and of the required shade shall be used.

15.46.2 Preparation of surface and application shall be as specified in 15.35 for new / old surface as the case may be.

15.46.3 Other details shall be as specified in 15.3.3 as far as they are applicable.

15.47. SPECIFICATIONS FOR PAINTING WITH ANTI-CORROSIVE BITUMASTIC PAINT

15.47.1 Ready mixed paint (conforming to IS: 158-1981) shall be of approved brand and manufacture.  It shall be black, lead free, acid-alkali-heat-water resistant.

15.47.2 Preparation of surface and application shall be as specified for painting on new or old surfaces as the case may be.

The drying time between consecutive coats, however, shall be not less than 3 hours.

15.47.3 Other details shall be as specified in 15.3.3 as far as possible.

15.48 SPECIFICATIONS FOR FLOOR PAINTING

15.48.1 Floor paint of approved brand and manufacture and of the required colour shall be used.

15.48.2 Preparation of surface - All dirt, grease shall be removed from the floor by wiping with rags, soaked in turpentine and scrapping where necessary and then washing with warm water containing caustic soda or washing soda in solution.  The floor should then be rinsed thoroughly with water and dried.  Cracks and holes shall then be filled with specified filler as recommended by the manufacturer and rubbed smooth.

It should be noted that the painting with floor paints shall not be done over concrete surfaces less than two years old.

Old surface shall be prepared as specified in 15.35.2.1(c)

15.48.3 Application - The number of coats as in the description of the item shall be applied.  Each one shall be allowed to dry for not less than 24 hours before the next coat is applied. The flooring should not be brought into use for a week after final coats that the painted surface can thoroughly harden.

15.48.4 Measurement - Measurements shall be as per actual length and breadth being measured correct to a cm.  The details given under shall hold good as far as applicable.

15.48.5 Other details shall be as specified in 15.33 as far as applicable.

15.49 SPECIFICATIONS FOR VARNISHING

15.49.0 Ordinary copal varnish or superior quality spray varnish shall be used. The work includes sizing of transparent wood filler.

15.49.1 Varnish (conforming to IS: 347-1975 for the finishing and undercoats shall be of approved manufacturer.

15.49.2 Varnishing on new surfaces

15.49.2.1. Preparation of surface - New wood work to be varnished shall have been finished smooth with a carpenter’s plane.  Knots shall be cut to a slight depth.  Cracks and holes shall be cleaned of dust.  The knots, cracks etc. shall then be filled in with wood putty made as follows:

On a piece of wood 20 x 15 cm face and on the side where cross grains appear, a small quantity of glue size shall be poured and the surface scraped with the edge of a fine carpenter’s  chisel.  Very fine wood powder shall be mixed with the glue and the stiff paste thus formed shall be used for the filing.

The fillings when dry shall be rubbed down with a carpenter’s file and then the entire surface shall be rubbed down perfectly smooth with medium grained and fine sand papers and wiped with dry clean cloth so that it presents uniform appearance.  In no case shall sand papers be rubbed across the grains, as in this case even the finest marks will be visible when the varnishing is applied.

15.49.2.2 Sizing or transport wood filler coat - The surface shall then be treated with either glue sizing or with transparent wood filler coat as stipulated in the description of item.

a)  Sizing - When sizing is stipulated, an application of thin clean size shall be applied hot on the surface.  When dry, the surface shall be rubbed down smooth with sand paper and cleaned.  It shall then be given another application of glue size nearly cold.  The sized wood work shall again be rubbed down smoothly with fine sand paper and cleaned.  The surface shall be perfectly dry and all dust shall be removed not only from the surface but also from the edges and joints before varnishing is commenced. If the wood work is to be stained, the staining colour shall be mixed with the second coat of the size which must be applied evenly and quickly keeping the colour on the flow.

Any joining up with work already dry will show badly.  The object of application of the glue size is to seat the pores in wood to prevent absorption of the oil in the varnish.

Glue sizing is inadvisable on floors, table tops and other horizontal surfaces likely to carry wet household utensils which are likely to disturb the size coatings and thus expose bare wood.

Where glue sizing is omitted to be done the rate for the work shall be suitably reduced :

b)  Transparent Wood Filler Coat - Where instead of glue sizing, transparent wood filler application is stipulated in the item, then the surface prepared as described shall be given as application of the filler with brush or rag in such a way that the filler fills up all the pores and indentations and levels up the surface. It shall be allowed to dry for 24 hours.  Then it shall be cut and rubbed with emery paper so that the surface of the wood is laid bare, with the filler only in the pores and crevices of the wood.

15.49.2.3 Application of Varnish - The number of coats to be applied shall be as stipulated in the description of the item.

The under coat shall be with a flatting varnish.  This dries hard and brittle and when cut and rubbed down to produce a smooth surface enhances the gloss of the finishing varnish.  The top coat shall be given with stipulated brand of finishing varnish.

The varnish shall be applied liberally with a full brush and spread evenly with short light strokes to avoid frothing. If the work is vertical the varnish shall be crossed and re-crossed and then laid off, latter being finished on the upstrokes so that varnish, as it sets, flows down and eliminates brush marks, the above process will constitute one coat.  If the surface is horizontal, varnish shall be worked in every direction, with light quick strokes and finish in one definite direction so that it will set without showing brush marks, in handling and applying varnish care should be taken to avoid forming froth or air bubbles.   Brushes and containers shall be kept scrupulously clean.

Rubbing down and flatting the surface shall be done after each coat except the final coat with fine sand paper.

The work shall be allowed to dry away from droughts and damp air.  The finished surface shall then present a uniform appearance and fine glossy surface free from streaks, blister etc.

Any varnish left over in the small container shall not be poured back into the stock tin, as it will render the latter unfit for use.

Special fine haired varnishing brushes shall be used and not ordinary paint brushes.  Brushes shall be well worn and perfectly clean.

15.49.2.4 Other details shall be as specified in 15.33 as far as they are applicable.

15.49.3. SPECIFICATION FOR VARNISHING ON OLD SURFACE

15.49.3.1. Preparation of surface - If the old varnished surface is firm and sound it shall be cleaned of grease and dirt with turpentine and then rubbed with wet sand paper until the surface is clean and smooth.  It shall be dried and wiped clean with a soft cloth.  Knots, holes and cracks shall be stopped as specified in 15.49.2.1.  The entire surface shall then be rubbed down smooth with sand paper and wiped clean.

If the old varnished surface is peeled or cracked then it will be necessary to remove the entire varnish as described in 15.54 and such removal shall be paid for separately outside the rate for varnishing.  Further the varnishing itself will have to be done like new work and will be paid for as such.

15.49.3.2 Application - The specification shall be same as described in 15.49.2.3 as far as applicable except that the coats to be applied will be with the stipulated quality of varnish for finishing coat.

15.49.3.3 Other details shall be as specified 15.33 as far as they are applicable.

15.50. SPECIFICATIONS FOR FRENCH SPIRIT POLISHING

15.50.1. Pure shellac conforming to IS: 16 varying from pale orange to lemon yellow colour, free from resin or dirt shall be dissolved in methylated spirit at the rate of 140 gm of shellac to 1 litre of spirit.  Suitable pigment shall be added to get the required shade.  Ready made polish conforming to

IS: 348-1968 can also be used.

15.50.2. Polishing new surface

15.50.2.1. Preparation of surface - The surface shall be cleaned. All unevenness shall be rubbed down smooth with sand paper and well dusted.  Knots if visible shall be covered with a preparation of red lead of glue size laid on while hot. Holes and indentations on the surface shall be stopped with glazier’s putty.  The surface shall then be given a coat of wood filler made by mixing whiting (ground chalk) in methylated spirit at the rate of 1.5 kg of whiting per litre of spirit.  The surface shall again be rubbed down perfectly smooth with glass paper and wiped clean.

15.50.2.2. Application - The number of coats of polish to be applied shall be as described in the item.

A pad of woolen cloth covered by a fine cloth shall be used to apply the polish. The pad shall be moistened with the polish and rubbed hard on the wood, in a series of overlapping circles applying the mixture sparingly but uniformly over the entire area to give an even level surface.  A trace of linseed oil on the face of the pad facilitates this operation. The surface shall be allowed to dry and the remaining coats applied in the same way.  To finish off, the pad shall be covered with a fresh piece of clean fine cotton cloth slightly damped with methylated spirit and rubbed lightly and quickly with circular motions.  The finished surface shall have a uniform texture and high gloss.

Measurements, Rate and other details shall be as specified as far as they are applicable.

15.50.3. SPECIFICATION FOR POLISHING OLD SURFACE

15.50.3.1. Preparation of surface - If the old polished surface is not much soiled it shall be cleaned of grease and dirt by rubbing with turpentine and then rubbed with fine sand paper.

If the old polished surface is much soiled then it will be necessary to remove the entire polish as described in 15.54 and such removal shall be paid for separately outside the rate of polishing. Further the polishing itself will have to be done like new work and will be paid for as such.

15.50.3.2. Application - The specifications shall be same as described in 15.50.2.2 as far as applicable.

15.50.3.3. Measurements and Rate and other details shall be as specified in 15.33 as far as they are applicable.

15.51. SPECIFICATIONS FOR OILING WITH LINSEED OIL

Raw linseed oil shall be lightly viscous but clear and of yellowish colour with light brown tinge.  Its specific gravity at a temperature of 30 degree C shall be between 0.923 and 0.928.  The oil shall be mellow and sweet to the taste with very little smell. Oil shall be clear and free from adulterants, sediment, suspended and other foreign matter.  Linseed oil which is turbid or thick, with acid and bitter taste and rancid odour and which remains sticky for a considerable time shall be rejected.  The oil shall conform in all respects to IS: 75.  The oil shall be of approved brand and manufacture.

15.51.2 Oiling new surface

15.51.2.1 Preparation of surface - This shall be done as described in 15.49.2.2 except that no sizing will be done on the prepared surface.

15.51.2.2. Application - The number of coats to be applied shall be as stipulated in the description of item.

The oil shall be applied freely with brushes (no rags) and spread evenly and smooth until no more oil is absorbed.  Each subsequent coat shall be applied after the previous coat is thoroughly dried and in any case not only before 24 hours of application of first coat.

15.51.2.3. Work after completion shall not be patchy and sticky to the touch and shall present a uniform appearance.

15.51.2.4. Other details shall be as specified in 15.33 as far as they are applicable.

15.51.3. Oiling on old surface

15.51.3.1. Preparation of surface - The wood work shall be cleaned of all smoke and grease by sand papering or by washing with lime and water.  The surface shall then be washed with soap and water and completely dried.

15.51.3.2 The specification for application shall be as described in 15.51.2.2

15.51.3.3 Other details shall be as specified in 15.33 as far as they are applicable.

15.52. SPECIFICATIONS FOR BEES WAXING OR POLISHING WITH READY MADE WAX POLISH

15.52.1 The polishing shall be done with bees waxing prepared locally or with ready made wax polish

of approved brand and manufacture, as stipulated in the description of item.

Where bees waxing are to be prepared locally, the following specifications for the same shall apply.

Pure bees wax free from paraffin or stearine adulterants shall be used.  Its specific gravity shall be 0.965 to 0.969 and melting point shall be 63 degree C. The polish shall be prepared from a mixture of bees wax, linseed oil, turpentine and varnish in the ratio of 2:1.5:1.0.5 by weight.

The bees wax and boiled linseed oil shall be heated over a slow fire.  When the wax is completely dissolved the mixture shall be cooled till it is just warm and turpentine and varnish added to it in the required proportions and the entire mixture shall be well stirred.

15.52.2. Waxing new surface

15.52.2.1. Preparation of surface - Preparation of surface shall be as described in 15.49.2.1 with the exception that knotting, holes and cracks shall be stopped with a mixture of fine saw dust formed of the wood being treated beaten up with sufficient bees wax to give it cohesion.

15.52.2.2. Application - The polish shall be applied evenly with a clean soft pad of cotton cloth in such a way that the surface is completely and fully covered.  The surface is then rubbed continuously for half an hour.

When the surface is quite dry, a second coat shall be applied in the same manner and rubbed continuously for one hour or until the surface is dry.

The final coat shall then be applied and rubbed for two hours (more if necessary) until the surface has assumed a uniform gloss and is dry, showing no sign of stickiness.

The final polish depends, largely on the amount of rubbing which should be continuous and with uniform pressure with frequent changes in the direction.

15.52.2.3. Other details shall be as specified in 15.33 as far as they are applicable.

15.52.3. Waxing old surfaces

15.52.3.1. Preparation of Surface - The wood work shall be cleaned of all smoke and grease by washing with lime water.  The surface shall then be washed with soap and completely dried.  Then it shall be prepared smooth as specified in 15.49.2.1.

15.52.3.2. Application - The polish shall be applied in the manner specified in 15.52.2.2.  In this case one or two coats shall be applied as necessary to get uniform gloss, instead of three coats in the case of new work.

Other details shall be as specified in 15.33 as far as they are applicable.

15.53. SPECIFICATIONS FOR LETTERING WITH PAINT

15.53.1. Black, Japan paint (conforming to IS: 341) or ready mixed paint as ordered by the Engineer shall be used.  The paint shall be of approved brand and manufacture.  Ordinary ready mixed paint shall be of the shade required by the engineer.

15.53.2. Lettering on new surface

125.53.2.1. Application - The letters and figures shall be to the heights and width as ordered by the engineer.  These shall be stenciled or drawn in pencil and got approved before painting.  They shall be of uniform size and finished neatly.  The edges shall be straight or in pleasant smooth curves.  The thickness of the lettering shall be as approved by the engineer.  Lettering shall be vertical or slanting as required.

Two or more coats or paint shall be applied till uniform colour and glossy finish are obtained.

15.53.2.2. Measurements - Measurements shall be taken in terms of letter cm (the measurement relates to the vertical height of the lettering).  The letter heights shall be measured correct to a cm.

Dots, dashes, punctuations and other similar marks or lines shall not be measured for payment.

In Devanagiri script dots & matras occurring with the letters shall not be measured.  Half letter shall be measured as full letter.  The height of letters shall be measured excluding the Matras projecting above the heading and matras below the letters.

15.53.2.3. Rate - Rate shall include the cost of all labour and materials involved in the operations described above. The rate per cm height of letter shall hold good irrespective of the width of the letters or figures or the thickness of the lettering.

The same rate will apply irrespective of whether black Japan or ready mixed paint of any shade as required is used.

15.53.3. Relettering on old surface

15.53.3.1. Painting shall be done over the existing letters and shall accurately follow their lines and curves.

One or more coat of paints shall be applied till a uniform colour and glossy finish is obtained.

15.53.3.2. Measurements and Rate shall be as specified in 15.53.2

15.54. SPECIFICATIONS FOR REMOVING OLD PAINT

15.54.1. With patent paint remover

15.54.1.1. Patent paint removers shall consist of volatile organic liquids thickened with waxes and other ingredients to retard the evaporation of the liquid and to enable a substantial layer of remover to be applied to the surface.  The paint remover shall be of a brand and manufacture approved by the engineer.  It shall be free from alkaline matter and non-caustic so that it can be handled by workmen without injury.  It shall be of non inflammable quality as far as possible.

15.54.1.2. Application - Paint remover shall be used where burning off with blow lamp is not suitable.  The paint remover shall be applied liberally with a brush and allowed to remain on the surface for a period depending on the particular brand of remover used and on the thickness of the paint coating to be removed.  When the paint film lifts and wrinkles under the action of the remover it shall be stripped with a sharp instrument.  If the film is not thoroughly removed a second coat of remover may be applied if necessary over such patches and then the film thoroughly scrapped.

After the surface has been stripped, it shall be washed down with mineral turpentine to remove all traces of paraffin wax, which forms one of the ingredients of patent paint remover and which if left in place will prevent the paint from drying.

The cleaned surface shall be suitably prepared for application of paint or other finish.

15.54.1.3. Precautions - Where the paint remover used is of the inflammable type, suitable precaution against risk of fire shall be taken.

Neighboring painted surfaces which are not to be treated should be properly protected from contact with paint remover.

15.54.1.4. Preparation of surface - The surface shall then be prepared as described in 15.34.2

15.54.1.5. Measurements - Specifications in 15.33.6 shall hold good.

15.54.1.6. Rate - Rate shall include the cost of all labour and materials involved in all operations described above.

15.54.1.7. Other details shall be as specified in 15.33 as far as possible.

15.54.2. With caustic soda solution

15.54.2.1. Application - Caustic Soda dissolved with 48 times its volume of water shall be applied to the old paint with a brush and when the paint film lifts and wrinkles it shall be thoroughly scrapped of in the same way as described. After the surface has been stripped thoroughly, it shall be rinsed with several chances of clean water to remove all traces of alkali, which if allowed to remain are liable to spoil the new paint applied over it.  A little acetic acid or vinegar added to the final change of rinsing water helps to neutralize any remaining alkali.

15.54.2.2. Precautions - Caustic soda as its name implies is a corrosive liquid and care should be taken to see that no liquid spills over the skin or clothing.

15.54.2.3 Preparation of surface, Measurements, Rate and other details shall be as specified in 15.54.1

15.54.3. With blow lamp - The paint shall be removed either with a blow lamp or with air acetylene equipment.  The flame shall be allowed to play upon the paint just enough to soften it without charring either the paint or the background.  The softened paint shall then be removed with a stripping knife following the flame as it is moved up the surface.

Burning off shall begin at the bottom of the vertical surface and shall proceed upwards.

15.54.3.2. Precautions - Removal with blow lamp shall not be done on narrow or caved under cut surfaces or where there is risk of damage to neighboring materials such as panes in glazed windows.

15.54.3.3. Preparation of surface, Measurements, Rate and other details shall be as described in 15.54.1

Neighbouring painted surfaces which are not to be treated should be properly protected from contact with paint remover.

15.55. SPECIFICATIONS FOR WASHED STONE GIRT PLASTER

15.55.1. Scaffolding shall be as specified in 15.1.1

15.55.2. Preparation of surface shall be as specified in 15.1.2 and 15.8.2

15.55.3. Materials

15.55.3.1. Stone chippings obtained by crushing hard stone shall be free of dust and deleterious material.  10 mm nominal size stone chippings, where specified, shall pass 100% through 12.5 mm sieve and fully retained on 6.3 mm sieve.  Stone chippings shall be thoroughly washed with water and sieved before use.

15.55.3.2. Mortar - Cement mortar for under coat and cement mortar to be mixed with stone chippings for top coat shall be as specified.

15.55.4. Application of plaster

12 mm under coat - Under coat of cement mortar 1:4 (1 cement : 4 coarse sand) shall be applied as specified except that the finishing, after the mortar has been brought to level with the wooden straight edge, shall be done with wooden float only.  The surface shall be further roughened by furrowing with a scratching tool.  Furrowing shall be done diagonally both ways and shall be about 2 mm deep to provide a key for the top coat.  The scratched lines shall not be more than 10 cm apart. The surface shall be kept wet till top coat is applied.

15 mm top coat

15.55.4.1 - Top coat comprising cement mortar and stone chippings shall have an overall proportion of 1:0.5:2 (1 cement: 0.5 coarse sand: 2 stone chippings 10 mm nominal size) or as specified.  The top coat shall be applied a day or two after the under coat has taken the initial set.  The surface of the under coat shall be cleaned and a coat of cement slurry at 2 kg of cement per sqm shall be applied in uniform thickness on the under coat after the application of slurry and sufficiently pressed with wooden float for proper bonding with the under coat. Vacant space, if any shall be filled with the specified mix.

15.55.5. Finish - The top coat of plaster shall be finished to a true and plumb surface.  The surface shall be tested frequently as the work proceeds with a true straight edge not less than 2.5 m long and with plumb bobs.  All horizontal lines and surfaces shall be tested with a level and all jambs and corners with a plumb bob as the work proceeds.  All the corners angles and junctions shall be truly vertical or horizontal as the case may be.  Rounding or chamfering of corners junctions etc. Where required shall be true to template.

Finished surface of the top coat after the mix has taken the initial set, shall be scrubbed and washed with suitable brushes and plain water. Scrubbing and washing shall continue till the stone chippings are sufficiently exposed.  Stone chippings which may come out while scrubbing shall be replaced using the specified mortar mix.  A sample of the washed stone grit plaster shall be got approved from the Engineer.

15.55.6. Grooves - Grooves of size 15 mm x 15 mm or as specified shall be provided as shown on the drawing or as required by the Engineer.  Tapered wooden battens to match the size and shape of the grooves shall be fixed on the under coat with nails before the application of the top coat and these shall be removed carefully so that the edges of the panels of top coat are not damaged.  Damage, if any, shall be made good by the contractor.

15.55.7. Curing shall be done as specified except that the dates are not to be marked.

15.55.8. Measurements

15.55.8.1. Length and breadth shall be measured correct to the nearest cm and the area shall be calculated in sqm correct to two places of decimal.

15.55.8.2. Measurements shall be taken for the work actually done with deductions for all openings and addition for all jambs soffits and sills. However, no deduction is to be made for the grooves provided as specified in 15.55.6

15.55.8.3. Washed stone grit plaster on circular surfaces not exceeding 6 m in radius and on external surfaces at a height greater than 10 m shall be measured separately.

15.55.8.4. Rates - The rates shall include the cost of all labour and materials involved in all the operations described above except for providing grooves.  The length of grooves shall be measured in running meters and paid for separately.

Annexure 15-A.1

PAINTING OF MASONRY, CONCRETE AND PLASTER SURFACES

(Extract from SP-62 (S & T)-1997 published by B.I.S)

1 General - This part will deal with painting, namely, distempering, oil paint, emulsion paint, cement paint, synthetic gloss paints, bituminous paints, etc, on masonry, concrete and plaster surfaces (calcareous surfaces).

2 Materials - Dry distemper shall conform to IS: 427-1965; oil bound distemper to IS: 428-1969 enamel interior and exterior paint to IS: 133-1993 and IS: 2933-1975 and cement paint to IS: 5410- 1992.

3 Characteristics of the background and treatment

3.1 General - In painting, calcareous surfaces, careful consideration shall be given to physical and chemical properties of the background and the backing materials which are strongly alkaline. Concrete, lime and cement plasters are likely to cause alkali attack on paint.  This will have to be clearly distinguished from materials which are neutral or neatly so, as in the case of calcium sulphate plasters. The characteristics of different calcareous surfaces are described in Annexure 15-A.2

3.2 Planning of all painting operations in relation to dampness in the background

a)  When painting new walls, any type of paint system which will seal in the moisture shall be avoided.

b)  The material for initial decoration shall therefore be chosen in due relation to the ultimate scheme for re-decoration. If. For example, it is intended eventually to paint the surface with an oil paint, the initial decoration shall be done either with a material which can be removed easily and completely, or with one which is suitable to receive oil paint.

c)  When the surface has properly set and cured and when all excess moisture has dried out from it from the backing and further movements of moisture will be negligible, painting may be done as specified, it being merely necessary to select an alkali resistant priming paint when oil based paints are used to suit the porosity of the surface.

d)  However, where it will not be possible to allow the required time for the surface to dry out fully, the decoration in such cases shall be with a porous finish, such as, lime wash, colour wash, cement paint, oil-free distemper or suitable emulsion paint which will allow drying to continue at a reasonable rate through their films.  Gloss paint shall not be used until drying is complete.

e)  If a surface remains persistently damp, the cause shall be examined and the surface suitably treated before attempting to decorate.  If remedy is impractical, isolation of affected surfaces by battening out and plastering or boarding may be necessary.  Local areas affected by efflorescence shall be cut out and replastered or treated with efflorescence foil of aluminium to prevent the absorption of water from the exterior or penetrations of water into the interior ( Annexure 15-A.3)

3.3 Painting and other finishes on both sides of the wall - Painting new walls or partitions on both sides may result in an increased risk of the paint failure, because the means of escape of water introduced during construction operations are restricted. A difference in porosity of the paint films applied to either side of a wall may result in one side being more affected than the other.  The risk is similar and greater when only one side is painted and the other side is sealed by some impermeable treatment, for example, wall tiling.  Particularly severe conditions may be met when walls, partitions and ceilings are built of  materials that need large quantities of water for curing and setting.  For solid walls, partitions and ceilings, the precautions outlined shall be carefully observed.

3.4 Variation in suction - The variation in suction characteristics of the surface to be painted require corresponding variation of the priming coat, or in some cases, the use of glue size , petrifying liquid  or sealers according to the type of paint to be used.  Surfaces which show local variations in suction, for example, between individual bricks or on patches produced on plastered surfaces by local over-trowelling or by efflorescence, shall be treated by the application of suitable primer.  Lime plaster finishes have a moderate suction, which can easily be counteracted by use of sealers.

If the suction is so high or variable that a normal painting procedure is unlikely to give a good finish, one of the following pre-treatments  shall be applied over the whole surface as a primer, according to the type of paint to be used

Sl. No.

Type of Paint

Pre-treatment

1.

Size bound distemper

 

 

1) One coat application

A coat of clearcole

 

2) Two coat application

A coat of size alone will be sufficient

2.

Dry Distemper

A coat of the same distemper thinned with water or petrifying  liquid supplied by the manufacturer. Or A coat of sharp colour or primer-sealer with the addition of finely ground pumice.

3

Oil paint           

A coat of thin primer or primer-sealer, preferably in consultation with the manufacturer of the paint.

4

Emulsion paint

A coat of the same paint thinned with water or sealers recommended by the manufacturer.

5

Cement paint and lime wash

Wet the surface before applying paints.

3.5 Surface imperfections - Imperfections on surface either plastered or otherwise mar the appearance of the paint finish and are especially conspicuous if the finish is glossy.  Where smooth finishes are required, particular attention shall be paid to the preparation of the surface, including any necessary rubbing down, sealing stopping or filling.

Plaster, if improperly gauged and worked, is liable to develop surface crazing (map crazing). This defect, if present, shall be treated according to the method given 4.1.1 and 4.1.2 before painting to prevent the cracks or their positions form showing in the finished work.

3.6 Growth of moulds, fungi, algae and lichens

a)  Characteristics of mould growth – The growth of mould is generally associated with continued dampness, either of the material painted or of the surrounding atmosphere. It shows itself in the form of black or vari-coloured spots or colonies which may be on, in or beneath the paint film, and are easily recognizable under microscope.  Mould growth may occur on almost any type of building material, including plastered surfaces.  Some growths may penetrate the underlying plaster or brickwork and become difficult to eradicate. On new work mould growth is unlikely to be encountered.  The surface of old work (covered as it may be with wall paper, distemper, or oil paint) may already  be infected with mould, particularly in premises which have been left unoccupied for sometime or where there has been a persistent damp penetration, and especially where walls have been saturated with water in the course of fire fighting.

b)  Precautions – Exterior surface of porous building materials like brick, stone and cement rendering, especially if unpainted, may develop growth of vegetation ranging from thick beds of moss to slimy steaks or patches of algae.  Any such growth shall be removed and ammoniacal copper solution (see Note) shall be applied to the surface and allowed to dry thoroughly before painting.

Note - A recommended composition and concentration of the ammoniacal wash shall consist of 7g of copper carbonate dissolved in 80 ml of liquor ammonia and diluted to 1:1 with water. Alternatively, 2.5 per cent magnesium silico-fluoride solution may be used.

c)  For prevention of recurrence of mould growth the following procedure shall be followed :

1)  Remove the source of dampness and dry out the walls ;

2)  Improve ventilation, if necessary;

3)  Remove the infected paint or paper; and

4) Sterilize the surface by applying an antiseptic wash, such as, 2 percent sodium pentachlorophenate or any other proprietary material and allowed to dry.

4 Preparation of background

4.1 For lime plaster surfaces - In the case of new lime plaster, precautions with regard to the drying of background shall be observed carefully as these will considerably affect the performance of the finish.  In case of new lime plaster, the essential principles with respect to drying of background will be the following:

a)  If possible lime plaster shall be left unpainted for the first few months so as to allow the plaster to carbonate, harden and dry thoroughly. If the plaster has any tendency to craze or crack owing to shrinkage on drying, the movements shall be allowed to occur before the surface is painted so as to enable provision of suitable proprietary treatment.  Heating the rooms, if accompanied by good ventilation, will assist drying, but shall be cautiously adopted. Too rapid a drying may damage the plaster by causing undue shrinkage and separation of the plaster coats.

b)  If there is any objection to leaving the plaster bare, a temporary decoration of soft distemper may be applied.  This may be removed easily at a later date and replaced by a more permanent decoration. Other types of paint suitable for early application are cement paints, silicate paints and washable distemper depending of the final decoration in view.

c)  If the background of the plaster is one likely to contain large amounts of water, for example, new brickwork, concrete or building blocks, no attempts shall be made to apply oil paint (especially gloss finish) until there is every reason to believe that the walls are thoroughly dry.  Some indication of the progress of drying can be obtained by means of tests described in 15-A.3

d)  If the background is of a dry type, for example, wood or metal lath, oil paints may be applied with safety after a few weeks of drying, and oil bound distempers even earlier.

4.1.1 In case of old unpainted plaster surfaces any source of dampness in walls and ceilings shall be removed and painting shall be deferred until the plaster has dried.

Any major cracks or defects in the plaster shall be cut out and made good. Cracks may be wetted thoroughly prior to filling or priming paint may be applied to the sides of cracks to avoid  undue absorption of water and subsequent shrinkage of the filling.  For filling, a retarded hemi-hydrate calcium sulphate plaster gauged with about one-third of its volume of hydrated lime may be used.

Prior to painting, fine cracks may be filled with a mixture of oil, putty and white lead or a distemper type of filling composition depending on the finish which is to follow.

4.1.2 In the case previously painted lime plaster surfaces the following precautions shall be observed:

a)  Any existing fungus or mould growth shall be completely removed. The surface shall be thoroughly scraped and rubbed down with bristle brush and sand paper and then washed down with clean water and allowed to dry. A coat of fungicidal wash shall then be applied and left for sometime to dry thoroughly.  The surface shall be kept under observation for sometime during drying out period and if the mould recurs, the treatment and drying shall be brushed with soft bristle brush to remove any dust particles 24 h after the wash.  Painting shall be carried out over the fungicidal wash without removing it with water.

b)  Any existing paint showing extensive flaking, bleaching or saponification (as shown by stickiness or the presence of yellow soapy runs) shall be removed by scraping and washing and the surface allowed drying completely. It may then be repainted as prescribed for new surfaces.

c)  Local defective patches shall be treated individually by removing all loose or softened paint and bringing forward the treated patches with primer and under-coating before applying a fresh coating over the white areas.

d)  Dry distempers and lime wash shall be totally removed prior to repainting. It may sometimes be necessary to wet the surface before scraping. This shall not be overdone and all surfaces shall be perfectly dry prior to the application of any priming coats.

e)  Certain wall and ceiling surfaces may reveal hairline cracks. After complete removal of the existing paint systems and if the lime plaster has cured and dried completely, use at least two coats of any of the primers for the paint system to be adopted. When oil paint is to be used, the primer at least shall be of alkali resistant type.  Lime fast pigments shall be used.

f)  Water based paint or washable distemper, if in a clean, sound condition, need not be removed if similar coatings are to be applied in the new paint system. By using a mild detergent, the surface may be washed and then after a light sanding it will be ready to receive a fresh coat (with spot priming, if required).

4.2 For Cement and Cement Concrete Surfaces - For new surface it is preferable than the surface is left unpainted for as long as possible to allow drying.  Before painting, the surface shall be thoroughly brushed to remove all dirt and remains of loose or powdered materials.

Treatment of the surface with solution of acids or salts, such as, zinc sulphate is not advisable as the risk of not reducing the alkali attack appreciably and efflorescence may be increased.  But on old unpainted surfaces, if there is an extensive growth of vegetable material which cannot be removed by brushing, the growth shall be destroyed by applying a wash of ammoniacal copper solution in accordance with 3.6(b). The dead and dry remains of the growth shall be brushed off prior to painting.  Any loose or uneven areas or any major cracks in cement concrete or plaster background shall be cut out and made good and the repairs allowed to dry thoroughly before painting is commenced.  Minor repairs may be made with cement mortar. Cement plaster or concrete which is previously painted shall be prepared in the same manner as in 4.1.2.

4.3 For Gypsum Plaster Surfaces - Before application of the paint it shall be ensured whether the surface is alkaline or neutral and the alkalinity may be tested in accordance with Annexure 15-A.3

If the surface of the plaster has a patchy appearance and shows wide variation in suction due to efflorescence or other causes, a paint primer shall be applied before application of a regular paint.

For old surfaces, unpainted or previously painted, the preparation of background will be the same as in the case of lime plasters. If it is a neutral surface, the application priming paint may not be necessary.

4.4 For Masonry surfaces - All mortar joints shall be brought to a sound condition before painting operations are started.  In the case of new brickwork, painting shall be deferred for at least three months after completion of the masonry work and longer if the weather during this period has become unfavourable for drying.  Dirt may be removed by washing with water. In case of old masonry, wherever there is extensive growth of vegetable matter, it shall be treated suitably according to 3.6.  Previously painted surfaces of brickwork shall be prepared in the manner given in 4.1.2.

4.5 For Asbestos cement surfaces - Asbestos cement being based on Portland cement will be, specially when new and damp, sufficiently alkaline to attack oil paint. The asbestos cement sheets are porous, permit suction and also fungus growth on them.  The necessary precaution in the painting work to overcome there difficulties are as below:

a)  The best way, probably, to reduce the risk of alkali attack is to allow the sheets to weather for some months. The alkali becomes carbonated on exposure to air, and rain will often wash them off the surface to some extent.  With long exposure, however, surfaces become powdery and dirty, and offer poor key for paint unless properly cleaned. Although weathering reduces the risk, it may not entirely overcome the danger of alkali attack.

b)  Asbestos cement sheets shall not be treated with chemicals like hydrochloric acid or zinc sulphate to neutralize the alkalis. Also the use of chemicals will often leave powdery deposit on the surface which may interfere with adhesion of paint. The use of hydrochloric acid for cleaning will also make the asbestos cement sheet brittle.

c)  Asbestos cement sheets are porous in varying degrees and moisture absorbed will often cause failure of paint system. It is therefore essential that asbestos cement sheets are dry when they are painted.  To ensure this each sheet shall be left with both sides exposed to good drying conditions for 7 to 10 days before painting.

d)  When there is a danger of moisture entering the sheets from the back owing to dampness or condensation, ‘back painting’ shall be done with an alkali –resistant primer conforming to IS 109 : 1968 or bitumen paint conforming to IS 158 : 1981 or a colourless waterproofer.  Usually ‘back painting’ will have to be done before the sheets are fixed and will be particularly necessary where impervious painting system is adopted for painting of the surface. Back painting means coating the back and edges of the sheets with a specified paint to prevent entry of moisture from the back. Whenever impervious paint or paint system is used on the face, ‘back painting’ shall be done.  When the backs of sheets are inaccessible for back painting, a porous paint shall be chosen. Porous paints will allow the sheets to breathe so that there is less risk of trouble caused by moisture.

e)  Glazed patches are often visible on asbestos cement sheets and they have to be roughened to provide a key to the paint. More absorbent patches, which are whiter than the rest on the surface, tend to suck medium out of the paint and this is likely to affect the durability of the paint on these patches. The suction is also high and also variable. To overcome this effect pre-treatment with primer as mentioned in the paint schedules shall be applied over the whole surface. Application of the primer shall be minimum two coats.

If the suction is very high and variable that normal painting procedure is unlikely to give a satisfactory finish, suitable pre-treatment to the surface shall be given as described in 3.4.1.

f)  It is important to remove and kill any existing fungus growth.  For this the surface shall be scraped and rubbed down with glass wool and sand paper and then washed down with clean water and allowed to dry. A coat of fungicidal wash shall then be applied and left for sometime to dry thoroughly (see 3.6 and 4.1.2) 

4.5.1 Preparation of surface - The surface shall be cleaned by rubbing with sand paper. Any glazed area shall be roughened. Loose powdery material after rubbing shall be brushed off. Wire brushes shall be avoided in cleaning operations as they will lead to difficulties from deposited particles of iron causing iron stains.

In the case of previously painted surface the preparation of surface shall be as in 4.1.2 applicable. Before applying the paint finish, sheets shall be given final sand papering and then washed down with clean water and allowed to dry thoroughly. If the old paint film is sound, one or two coats only of any of the finishing paints may be applied.

5. Application of paints - The application of paints shall generally be as given in Table A.1 and Table A.2 along with pre-treatments where necessary for corresponding types of paints. The painting operations shall be as given in section 15.

Table-1 Schedules for painting new calcareous surfaces-interior (Clause 5.1)

Sl. No.

Final Finish Required

Primer  Coat

Under Coat

Finishing Coats

1

2

3

4

5

1

Whitewash       

One coat of whitewash

---        

Whitewash (two coats)

2

Colour wash

One coat of colour wash

---

Colour wash (two coats)

3

Distemper

 

 

 

 

a) Dry distemper

Clear Cole or size, etc.           

Filler to be used, if required

Dry distemper (two coats) (IS: 427-1965)

 

b) Oil bound Distemper

One coat of alkali resistant primer

-do-

Oil bound distemper (two coats) (IS: 428-1969)

4

Emulsion PaintÊ

One coat of emulsion paint    

-do-

Emulsion paint(two coats) (IS: 5411 (Part 1)- 1974)

5

Flat / Semigloss Paint Ê

One coat of alkali resistant primer

Undercoat as required,

Flat/Semigloss paint (two coats) filler, if required

6

Gloss Paint Ê

- do -

- do -

Gloss paint (two coats) (IS: 133-1993)

7

Chemical resistant paint Ê             

One coat of the paint required

Filler, if

Chemical, resistant paint (two coats)

8

Cement Paint Ê

One coat of cement paint

Nil

Cement paint (two coats) (IS: 5410-1992)

9

Bituminous Paint Ê

One coat of the paint           

Nil

Bituminous paint(two coats) (IS: 9862 -1981)

Ê May be thinned according to manufacturer’s recommendation.

Table-2 Schedules for painting new calcareous surfaces – exterior (Clause 5.1) 

Sl. No.

Final Finish Required

Primer   Coat

Under Coat

Finishing Coats

1

2

3

4

5

1

Whitewash       

One coat of whitewash

Nil       

Whitewash(two coats)

2

Colour wash

One coat of whitewash

Nil       

Colour wash(two coats)

3

Emulsion paint Ê

One coat of emulsion paint

Filler, if required           

Emulsion paint (two coats) (IS: 5411(Part 2)-1972

4

Flat / Semi gloss paint Ê           

One coat of alkali resistant primer

Under coat as required

Flat/ Semi gloss paint (two coats) (IS: 168-1973 and IS: 1232- 1964)

5

Gloss paint Ê

- do -   

- do -   

Gloss paint(two coats) (IS: 2932-1993 and IS:  2933-1975)

6

Chemical resistant paint

One coat of the paint

Filler, if required

Chemical resistant paint(two coats)

7

Cement paint Ê

One coat of cement paint

Nil       

Cement paint(two coats) (IS: 5410-1992)

8

Bituminous paintÊ

One coat of the paint

Nil       

Bituminous paint (two coats) (IS9862:1981 & IS: 158-1981)

Ê  May be thinned according to manufacturer’s recommendation

5.1.1 Normally stopping or filling as required be carried out before any painting is done and care should be taken to see that any cracks between plaster and wood work (for example, skirtings) are securely filled. If such cracks are wide, caulking with hemp or similar material may be necessary to support the filling and prevent it falling away through the gaps. Minor defects are frequently more apparent once the priming or first coat has been applied, and if any further stopping or filling is done over this first coat the area must be brought forward with appropriate paint to restore even porosity over the surface.

5.1.2 In regard to painting of asbestos cement sheets, the following points may be noted

a)  Asbestos cement sheets shall be thoroughly dry at the time of painting;

b)  Back painting shall be done when an impervious paint system is adopted for the finish, if practicable it shall be done after the face of the sheet has been painted, though, normally back painting will have to be done before the sheets are fixed.

c) For external sheeting an alkali-resistant paint either porous or impervious(with back painting) may be chosen.

d)  Where it is desired to tone down the natural colour of the sheets, a wash of green copper (as ferrous sulphate about 0.1 g/ml of water) shall be used. This will give a durable brownish stain, although the finish is unlikely to be uniform.

e) Gutters, down pipes, etc, should receive water-proofing coating of bitumen on the inside.  For outer surfaces alkali-resistant porous paint shall be used.

f)  For painting asbestos cement sheets, in choosing a paint system for a particular job, the risk of attack by alkali shall be taken into account. Paints which are by themselves highly resistant to alkali attack may be used. But where paints used are not alkali-resistant, at least two coats of alkali-resistant primer shall be applied. The primer shall not only be resistant but also form an impervious barrier so that alkali cannot get through to attack the paint system above.

5.2 Maintenance - In case of painting relating to maintenance work, the principles given in Table 3 should generally be applied.

Table -3  Recommended practices for maintaining painting (Clause 5.2)

Sl. No.

Condition of Surface

Cleaning and Painting Practice (see Notes 1 and 2)

Blistering and Softening

Efflores- -cence 

Chalking

Cracking

Flaking

1

2

3

4

5

6

7

1)

Nil

Nil       

Yes

Nil

Nil       

Clean, rub down with abrasive paper, apply one finishing coat.

2)

Nil

Yes     

Yes     

Nil       

Nil       

Rub down the affected surface to bare plaster, allow to dry, touch up with primer coat and then apply required number of coats; and follow by a reviver coat on the entire surface, if required.

3)

Yes     

Nil

Nil       

Nil       

Nil       

Scrap off the soft film, allow the surface to dry completely, touch up with primer coat & then apply required number of coats; and follow by reviver coat on the entire surface, if necessary.

4)

Nil       

Nil       

Nil       

Yes     

Nil       

Rub down and even up the surface with sand paper to remove cracked film. Touch up with primer and apply the required number of coats and follow by reviver coat on the entire surface, if necessary.

5)

Nil       

Nil

Nil       

Nil       

Yes

Remove the paint from the affected portion completely and follow part of or full schedule of painting as the case may be.

Notes 1) In case of any serious characteristics failure mentioned above (except chalking), the paint shall be completely removed and the full schedule of painting be followed.

2)  There is no effective remedy for efflorescence.

Annexure15-A.2

CHARACTERISTICS OF CALCAREOUS SURFACES WITH REGARD TO PAINT FINISH

1 Characteristics of lime plaster

a)  Lime plasters are highly alkaline and hence, until they are thoroughly dry and matured, they are likely to cause alkali attack on oil containing paints and distempers and fading of distempers. The severity of the attack varies with the proportion of soluble alkalis (soda and potash) in lime used, but it is always wise to take full precautions against alkali attack irrespective of the type of lime used.

b) Lime plaster finishes have a moderately high suction. This may be encountered by suitable adjustment of the priming coat.

c)  Lime plaster develops efflorescence less quickly than other plaster finishes.

d)  Lime plaster, if improperly gauged and worked, is likely to develop surface crazing.  This defect if present may be reduced by special treatment as described in 4.1.1 and 4.1.2 to prevent cracks or their positions showing in the finished painted surface.

e)  Lime plaster, being softer than other plasters, is liable to mechanical damage in certain solutions. The plaster shall, however, be made to harden more quickly by suitable gauging.

2 Characteristics of gypsum plaster

a)  When the plaster is properly set and hardened and the plaster backing and background are dry, gypsum plasters may be painted successfully with almost any type of paint except cement paint.

b)  The finishing coat of gypsum plaster can be applied over any type of undercoat; the undercoat does not affect the painting procedure and it is the composition of the plaster finishing coat that is chiefly to be considered.

c)  Plaster finishes gauged with lime involve a greater painting risk than other plasters, owing to the possibility of alkali attack. The risk is least with retarded hemi-hydrate gypsum plasters but for practical purposes, it is advisable to take precautions against alkali from any plaster to which lime has been added

d) Neat calcium sulphate plasters have no appreciable chemical action on paint, and the paint defects which occur on them are generally associated with the action of moisture and of efflorescent salts. On anhydride plaster, patches of efflorescence sometimes develop on areas differing in suction from remainder of the surface and there is a tendency for paint to fail in adhesion at these places. Extra care in priming is needed to secure adequate adhesion and even finish. The technique of ‘priming following the trowel’ helps to overcome the difficulty.

Retarded hemi-hydrate plasters, when exposed continuously to damp conditions, are liable to ‘sweet out’, a defect characterized by failure to harden or by disintegration. This may occur in various circumstances, for example, when the background of the plaster is permanently damp or when moisture is sealed into the plaster by premature application of an impervious paint film. Care shall be taken to avoid these conditions.

f)  Gypsum plasters are liable to a defect known as ‘dry out’ characterized by friable condition of the plaster surfacing and sometimes affecting the whole thickness of the finishing coat. It occurs when plaster is allowed to dry out too quickly before it had time to combine with all the water needed for setting and hardening processes. A ‘dry out’ can be caused by application of the plaster finish to a highly absorbent undercoat, by conditions favouring by rapid evaporation or by the premature application of artificial heat. An impervious backing to a thin plaster finishing coat may be as dangerous as one which is too absorbent, since it holds little or not reserve of water and the finish dries quickly.    

The condition of ‘dry out’ is not, usually, apparent at the time the surface is decorated but, if an impervious coat of paint is applied, water from the backing may cause expansion of the partially hydrated plaster producing ridges, blistering and disintegration in the plaster and often causing the paint to loose adhesion.     

g)   While, it is possible to obtain a satisfactory paint on any type of gypsum plaster, provided the appropriate precautions are observed, it is preferable, from the painters point of view that the plaster surface shall not be too highly trowelled and made non-absorbent. A plaster surface which shows a moderate and uniform degree of suction provides a margin of safety in the matter of paint adhesion. It is particularly desirable to have a surface of this type when emulsion paints, water paints and distempers are to be used, since these adhere less strongly, to impervious surfaces than do oil paints.

A gloss paint finish shows up any irregularities in the plaster surface, and hence, in places where such a finish is required, the plaster used shall be one which can readily be brought to a smooth level finish. To some extent, this conflicts with the requirements that the plaster shall be toweled only to the minimum needed to produce a smooth finish and no attempt shall be made to produce a high polish.

h)  Gypsum plasters may conform to IS: 2547(Parts 1 & 2)-1976.

3 Characteristics of cement and renderings

a)  New Portland cement concrete and renderings are strongly alkaline, and for this reason oil paints when applied to them are subject for saponification and bleaching.  In addition there is a risk of damage by efflorescence.

b)  The drying and surface combination cannot be hastened by treatment. Oil paint, therefore, shall not be used on such surfaces until several months have passed; but earlier decoration may be carried out with cement paints or silicate paints.

Annexure 15-A.3

APPLICATION OF ALUMINIUM FOIL TO CALCAREOUS SURFACES (Clause 3.2)

1 Procedure - The area to be treated shall be cleared of dust and allowed to dry prior to the application by means of a brush of a thin coat of bitumen primer conforming to IS 3384: 1986. Blown bitumen (penetration 10 to 20) conforming to IS: 702-1988 shall be hot applied by brush at a temperature of 175 degree C to the surface at the rate of approximately 1.5 kg/m2. The aluminium foil (0.025 mm thick) shall immediately be unrolled on the surface applied with hot bitumen. All joints shall have at least 50 mm overlap and shall be hot sealed. If required the blown type bitumen at 175 degree C at the rate of 1.5 kg/m2 may be applied over the aluminium foil or the bitumen sealer coat shall be painted with plastic emulsion paint or water based paint as required.

Annexure 15-A.4

TESTS RELATING TO FITNESS OF PLASTER FOR PAINTING (Clause 1.4.1 and 1.4.3)

1 Test for alkalinity

1.1 Representative areas of plaster shall be treated with oil-gloss paint or other alkali-sensitive paint (tinted with Prussian blue) and left for at least a week. If at the end the lime there is not sign of saponification or bleaching, conditions shall be reasonably safe for permanent decoration. If on the other hand, bleaching and saponification has occurred, further small areas shall be treated. This shall be repeated until sample areas remain undamaged.

1.2 Alternative procedure - Alkalinity may also be detected by the use of moistened red litmus paper on the surface. If it turns blue the presence of alkaline background may be inferred.

2 Test for efflorescence - Small areas of plaster where the efflorescence is most conspicuous shall be rubbed down with a suitable abrasive followed by the application of damp (not wet) cloth and left for at least one week. This process shall be repeated, if necessary, until no more salts appear. Conditions shall then be reasonably safe for permanent painting. The test shall be carried out under conditions of warmth and ventilation approximating those of occupational conditions.

3  Test for dryness - It shall be noted that those tests covered in C-1 and C-2 are not sufficient since a plastered wall may be neutral and show no signs efflorescence and yet be damp which is liable to cause paint to fail in adhesion. Moisture metre for testing the dryness of walls may be used in deciding when a surface has reached a condition to receive paint. However, no form of test may indicate the condition of more than a small area and since plastered well seldom dries uniformly, the test shall be repeated at a number of places. Again it shall be noted that deep seated moisture which is not always detected by superficial tests may make its presence felt after the surface is painted.                         

Annexure 15-A.5

SPECIFICATIONS FOR EXTERNAL RENDERED FINISHES

(Extract from SP-62 (S&T):1997 published by BIS)

1.1 General - ‘Rendering’ denotes generally external plaster and allied finishes, plain or textured, applied for the purpose of protection and decoration. Rendered finish can withstand different exposure conditions, such as, severe or moderate exposure to rain; dusty, clear or corrosive atmosphere, or subject to large variations in temperature or other climatic cycles.  Rendering increases, durability and ensures better performance.

1.2 Types of rendered finishes:

1.2.1 Toweled or floated plain finishes - Steel toweled finishes are not recommended for external renderings. Plain floated finishes require a high standard of workmanship to minimize the risk of cracking, crazing, and irregular discolouration.

1.2.2 Scraped or textural finishes, hand applied - Scraped or textured finishes are generally less liable to crack or craze than plain finishes are easier to bring to a uniform appearance; this is especially important when coloured renderings are used. Although rough texture offers more lodgment for dirt, it tends to an evenness of discolouration; rain water is disturbed reducing the risk of penetration through the rendering.

1.2.3. Hand-thrown finishes, rough cast and dry-dash, etc. - Three finishes have all the advantages of scraped or textured finish. Under severe conditions of exposure these are more satisfactory from weather proofing, durability, resistance to cracking and crazing than the types as in 2.1 and 2.2.

1.2.4. Machine applied finishes - There are various types, mainly proprietary materials and processes operated by specialists. The types are as follows:

a)  Finishes in which the material is thrown at random – These have an open porous structure, behave similarly to hard – applied scraped finishes and are equal to the latter and to hand-thrown finishes in water proofness, durability and resistance to cracking and crazing.

b)  Finishes which are applied by gun spray – These give low density porous finishes.

There are other finishes solely applied by means of cement gun under pressure which produces somewhat similar appearance to roughcast but less attractive. They are denser and therefore give very effective protection.

1.4.3. Nature of background in relation to choice of rendering - Broadly the background may be classified under the following types so far as application of rendering is concerned:

  1. Dense, strong and smooth materials ;
  2. Moderately strong and porous materials ;
  3. Moderately weak and porous materials ;
  4. No-fines concrete ; and
  5. Lathing or other similar backing materials.

The characteristics of these backgrounds are given in Table 1

1.4.4. Recommended mix proportions - Mixes suitable for different types of renderings are given in Table 5 Where alternate mixes are given selection shall be made on the following considerations:

a)  The mix for each successive coat shall never be of a type richer in cement than the mix    used for the coat to which it is applied; and

b)  Richer type of mix shall be preferred in winter conditions.

1.4.5. Preparatory work

1.4.5.1. Independent scaffolding may be used wherever possible to avoid put log holes.

Table 1 Background for renderings (Clause 1. 4.3)

Sl. No.

Backing Materials

Strength

Porosity and Suction

Mechanical Key and Adhesion

Resistance to Pene- tration, Protection Required

1

Poured cement Concrete

Strong

Low

Roughening, moistening & sometimes treating the surface with cement and grout (1:1) is necessary

Sufficient resistance; no further treatment apart from rendering

2

Cement concrete blocks

3

Bricks very dense type, stones     

4

Bricks ordinary porous type

Moderately strong

High    

Satisfactory; if suction is irregular use cement and sand mix 1:1over the  surface

Sufficient resistance, no further treatment apart from rendering

5

No – fine concrete          

Some times weak

Large voids a few small pores, capillarity absent; suction low      

Very satisfactory

---

6

Lathing

Shall be streng thened

---        

Purpose is to provide key

Two coats of rendering are necessary; First coat shall be of relatively impervious mix

 Table -2 Recommended mixes for external renderings (Clause1.4.4)

Background  Material

Type of Finish

Type of Mix Recommended for Given Exposure Conditions

First and Subsequent undercoat

Final Coat

Severe

Moderate

Light

Severe

Moderate

Light

1

2

3

4

5

6

7

8

Dense and strong  

Wood-float scraped or Textured

1         

2         

2 or 3

1

2

2,3 or 4

2         

3         

2 or 3

2

3

2 or 3

Moderately strong and porous 

Roughcast Dry – dash

5

5

5

6

6

6

5

5

5

-

-

-

Moderately weak and porous 

Wood-float scraped or Textured

2

3

4

Same as for undercoats

No-fines concrete

Wood-float scraped or Textured Roughcast Dry-dash

1

2

2 or 3

1

2

3 or 4

1

2

2 or 3

1

2

3 or 4

5

5

5

6

6

6

5

5

5

-

-

-

Metal lathing

Wood-float scraped or Textured

1

1

1

2

2

2

Or

 

Expanded metal

Roughcast Dry-dash

5

5

5

6

6

6

5

5

5

-

-

-

Notes

1)  Mix types – Type 1 – 1:0:4, Type 2 – 1:0.5 to 6, Type 3 – 1:1.6 to 7, Type 4 – 1:2.9 to 10, Type 5 – 1:0.3, Type 6 – 1:3

Types 1 to 5 shall consist of cement: lime: sand by volume; Type 6 shall consist of cement, coarse aggregate of size 6 to 12 mm by volume.

2)  For special mixes for high sulphate backgrounds (see 1.8)

3)  Where alternate sand contents are shown, the higher one may be used if the sand is coarse or well graded and lower sand content may be used of the sand is fine.

1.5.2 Preparation of Background

a)  The background shall be brushed with a stiff bristle or wire brush. Laitance if any on fresh concrete shall be removed.

b)  The background shall be roughened and moistened. Joints in masonry shall be raked to a depth of 1 cm.

c)  Adequate time shall be allowed between erection and application of rendering to make the surface suitable for suction adjustment. The backing shall be wetted, if it is dry, for this purpose; it shall not be soaked but dampened evenly.

d)  Ensure evenness of background before applying rendering.

e)  Differential movements of mixed back grounds shall be provided for.

6.0 Application of rendering coats

a)  General – When using high alumina cement, the work shall not be done in hot weather. Between coats, give 24h interval in hot and dry weather and more in cold weather.

b)  First undercoat – This may be applied either by laying or throwing from the trowel.  It shall be as uniform as possible up to a thickness of 8 to 12 mm. It shall be rough and then combed and scratched to provide a key to the next coat.

c)  Subsequent undercoat, if necessary, may be laid similarly to (b).

d)  Plain finishing coats – The finishing coat shall be not less than 3 mm or more than 8 mm thick; the coat shall be laid with a trowel and finished with a wood, felt, cork or other suitably faced float.

e)  Scraped or textured coats – Various scraped or textured finishes can be obtained by hand or machine application. The thickness of the final coat is governed by the texture required. For scraped finishes the final coat is of a thickness of 6 to 12 mm of which about 3 mm is removed in the scraping process. For textural finish the surface skin of the mortar shall be removed to expose the aggregate.

f)  Roughness finish – The final coat, the mix of which shall be quite wet and plastic, is thrown on by means of a trowel or scoop.

g)  Dry – dash finish

1)  For this finish the undercoat shall be up to a thickness of 8 mm and slightly pressed.

2)  The aggregate used for dashing shall be well washed and drained.

3)  To ensure satisfactory bond between the dashing and mortar, the aggregate may be slightly tapped into the mortar with a wood float or to a trowel.

h)  Machine – Applied Finishes – All damaged adjacent surfaces shall be masked. The finish shall be applied at such a rate as to ensure the desired texture.

7 Curing - The moistening shall commence as soon as the plaster had hardened; the surface shall be kept wet for at least 7 days by using a fine fog spray. Soaking of wall shall be avoided.

8 General - A separate support may be provided for the rendering on background with soluble sulphates.  A cement resistant to sulphate action may be used, namely sulphate resisting cement; or in very severe conditions high alumina cement or blast furnace slag cement may be used.

Mixes: For sulphate resisting cement the mixes indicated in Table given below may be used.  Where alternatives are given, the richer ones shall be used.

For alumina cement, lime shall not be mixed.  The mixes should be as below

1

In place of Type 1 mix

Use 1 part of high alumina cement: 3 parts of sand by volume.

2

In place of

Type 2 mix

Use 1 part of high alumina cement : ½ to ¾ part zinc sulphate powder: 4 parts of sand by volume

3

In place of

Type 3 mix

Use 1 part of high alumina cement: 1 part zinc sulphate powder: 5 to 6 parts of sand by volume.

Annexure 15.A.6

SPECIFICATIONS FOR EXTERNAL FACING AND VENEERS – STONE FACING

1 General - Facing with stone of various types like marble, granite, lime stone, etc., is a popular external finish. Therefore, these require careful fixing techniques involving proper preparation, appropriate choice of fixing device and weather proof construction. Fixing accessories, like cramps, dowels used in facing work are commonly of copper alloys but also of aluminium alloy, plastics, etc.

2 Materials

a)  Facing stone – The stone shall be sound, dense and free from defects which impair strength durability and appearance. The facings may be of marble, granite, basalt, limestone, sand stone or slate. Limestone slabs from Sahabad, Taiduran, Kotah and Yerraguntla of 20 mm thickness and above are used.

In case of sandstone, patches or streaks shall not be allowed; however scattered spots of 10 mm diameter may be allowed.

Marble facings (blocks, slab and tiles) shall conform to IS: 1130-1969.

The thickness of stone veneer shall not be less than 20 mm.

b)  Cramps – The material for cramps shall have high resistance to corrosion under conditions of dampness and chemical action of mortar in which it is embedded. They may be of copper alloyed with zinc, tin, nickel, lead and aluminium or stainless steel. Aluminium H9 alloy in W condition (see IS:  737-1986) may be used for cramps.

c)  Metal angle supports – Mild steel angle supports may be used; they should be protected from corrosion.

d)  Cement shall conform to IS: 269-1989, IS: 1489 (Parts 1 & 2)-1991 or any other as specified. Sand shall conform to IS: 2116-1980 and lime to IS: 712-1984 and SURKHI to IS: 1344-1981.

3 Types of facings

a)  Facings which are not integrally bonded with the backing do not generally appreciably contribute to the stability and load bearing capacity of the wall.

b)  Facings which are integrally bonded with the backing so that both together contribute to the stability and load carrying capacity of the wall in which at least 15 percent of the face consists of bonding stones extending up to 10 cm into the backing.

4 Fixing the facings with cramps - Cramps may be used either

a)  to hold the facing units in position only and transfer the weight of the unit to the facing beneath ; or

b)  to hold the units in position and also to support the unit transferring the weight to the backing.

Supporting arrangements shall be as shown in Fig. 1.A to 1 H; cramps may be attached to the sides (Fig. 1.A and 1.B), or top and bottom (Fig. 1.C, Fig. 1.D, Fig. 1.E and Fig. 1.F), or sides and bottom (Fig. 1.G and Fig. 1.H).

Facings integrally bonded to backing - The attachment for integral bond should be either

a)  The facing unit contains projections which are mechanically bonded with the backing and supporting unit; or

b)  By means of masonry bond or keying to the backing; or

c)  A combination of both (a) and (b).

5 Joints

The joints between units should be finished flush, tuck, ruled, square, weathered-struck or rebated as in Fig. 2.

Expansion joints in the backing shall be carried through in the facing.  The joints may be sealed with appropriate joint sealing compounds, to prevent ingress of moisture.

Note- Cramps shown in diagrams ' A-H' are arranged for facings with the longer sides vertical.  For facings having the longer sides horizontal, cramps would be positioned to suit the altered proportions of the facings.

Fig. 1 Diagrammatic arrangements of cramps for attaching facings to backing wall

Fig. 2 Types of finishes for joints

6 Fixing of stone facings - The stone facings shall be wetted before laying. While applying mortar for fixing the facings in position, no chips or fillings of any sort shall be used.

The facings may be fixed according to the different types of arrangements (see 4.1) and shown in Fig. 3.  In case of load bearing cramps (designed to carry the load), the holes in the backing shall be enlarged to improve the anchorage of the cramp.  During fixing, cramps shall not be bent, unless provided for in the design.

Use of stone dowels and metal pins for fixing veneering to wall are shown in Fig. 4. Cramps illustrated in Fig. 5 shall not be used for load bearing purposes. A detail of copper pin dowel is shown in Fig. 5. Details of metal and stone cramps are as in Fig. 6.

Fig. 3 Types of cramps for stone facings

Fig. 4 Details of fixing stone veneering

Fig. 5 Copper pin dowels

Fig. 6 Cramps

7 Finishing of joints - Exposed joints shall be pointed with 1:2:9 mortar as specified, the thickness of joint shall not exceed 6 mm.  For a close but joint the thickness shall not exceed 1.5 mm. Crushed sand stone from the same stone as the facing unit is preferable as the aggregate in mortar.

When distinct joints are necessary, a wiping of white cement slurry or tinted white linseed oil putty may be applied to the tightly butting slabs; but this shall not be used under severely exposed positions.

8 Ashlar facing -  Facing with ashlars built integrally with backing shall be as in KBS.

9 Control of alignment - Alignment shall be accurate to present a good appearance. Inaccuracies will easily show up.  Masking may be attempted by treatment of joints, such as, by use of chamfered, rounded or rebated edge in place of a simple square edge.

Annexure 15-A.7

SPECIFICATIONS FOR EXTERNAL FACINGS AND VENEERS – CEMENT CONCRETE

1 General -  Concrete slabs or precast blocks with different textures and finishes provide possibilities for a wide range of architectural treatment for external facing and are particularly suited for a wide scale adoption. While availability of natural stones is limited, concrete finishes can be made in a wide range of textures and colours.

2 Materials

a)  Precast concrete blocks shall conform generally to IS: 2185 (Part 1)-1979; IS: 2185 (Part 2)-1983; IS: 2185 (Part 3)-1984, and in addition shall have special treatment in regard to durability, colour and surface textures for the exposed facing. The size commonly adopted for concrete facing slabs is 600 mm x 400 mm x 30 mm. The face finish of slabs shall also be adequately waterproofed.  For obtaining various colours in the admixtures, reference may be made to IS: 2114-1984

b)  The material for cramps shall have high resistance to corrosion under conditions of dampness and chemical action of mortar or concrete in which it is embedded. The cramps may be of copper, alloyed with zinc, tin, nickel and aluminium or stainless steel. Aluminium alloy H9 in W condition (see IS 733: 1983) may also be used for cramps.

c)  Metal angle supports used shall be protected from corrosion.

d)  Cement shall conform to IS: 269-1989, IS: 455-1989, IS: 1489 (Parts 1 & 2)-1991 or any other as specified. Sand shall conform to IS: 2116-1980 and lime to IS: 712-1984, surkhi to IS: 1344-1981.

3 Types of facings and fixing by cramps

Facings and veneering may be of two types

a)  Attached facings for use with backing as a safe means of attachment without essentially contributing to the stability of the load bearing properties of the wall, and

b) Integrally reacting facings which are bonded with the backing and contribute to the structural stability and strength of the wall.

Cramps

a)  Using cramps to hold the facing units in position only, the weight of the unit being supported by the unit beneath, or

b)  Using cramps to hold the units in position and in addition to support the units thus transferring the load to the backing; or

c)  The facing unit may contain projections which mechanically bond into the backing and support the unit; or

d)  By means of masonry bond or keying to the backing; or

e)  By combinations of the above methods.

4 Supports - Supporting arrangements by means of projections which bond mechanically into the facing is a common method. Supporting by cramps are as shown in Fig. 1.A to 1.J Cramps may be attached to its sides (Fig 1-1A and 1B), or top and bottom (Fig 1-C to E), to its side, top and bottom (Fig 1-F to H), or in its centre (Fig 1-J).

5 Joints - The joints between facing units may be finished flush, tuck, ruled, square, weathered-struck or rebated. Where expansion joints are formed in the backing walls, they should be extended to the facing. The joints may be sealed with appropriate sealing compounds, to prevent ingress of moisture.

6 Fixing precast concrete slab facings - The facings can be fixed with butt joints, single or double joggle or grouted joints.  See figures 3 and 4. When the backing wall is of in-situ concrete it will be an advantage to use dove-tailed non-corrosive metal channels cast vertically in the backing wall in which one end of the cramps fit, the other end being cranked or drilled for dowels, the cramps being set into the channel as the fixing proceeds.

Note- Cramps shown in diagrams ' A-H' are arranged for facings with the longer sides vertical.  For facings having the longer sides horizontal, cramps would be positioned to suit the altered proportions of the facings.

Fig. 1 Diagrammatic arrangements of cramps for attaching facings to backing wall

Fig. 2 Types of finishes for joints

a)  Butt joints are the simplest form of joint and may be used when the facing unit has a projection into a backing to provide mechanical bond. It may also be used when it has no such projection with the arrangements, either for carrying the weight of the units by cramps or by the backing.

b)  In single joggle joint when side cramps are used they need only be single cramp as one side of the cramp is already held in position.  The positioning of single cramp will be easier than that of a double cramp; when ledged facing is used in conjunction with an inverted joggle joint, probably cramps may not be necessary.

c)  Double joggle joint is not suitable for vertical joints as the sliding action necessary to engage the unit vertically will interfere with the proper bedding of the horizontal joint and the bond to the backing with mortar. This type of joint is suitable for horizontal joints; it locks the units to one another but cramps may be required to hold the units to the wall.

Fig. 3 Details of cramp for precast concrete facings

d)  The grouted joints shall stabilize the facing system if applied to all horizontal and vertical joints. Cramps may be used for supporting the unit with the wall and also bearing load partially.

7 Control of alignment - The appearance of the finished wall will be easily marked by inaccuracies of alignment. Inaccuracies will to some extent be marked by the treatment of joints, for example, by chamfered, slightly rounded or rebated edge in place of simple square edge. Where practical the backing shall be built simultaneously with the facings to maintain correct alignment of facings. Treatment of joints will avoid chipping due to handling.

Fig. 4 Precast concrete facing cramp and joint details

Note - The inverted joggle joint at the top of the ledge is suitable only when the joining is applied to a cavity wall

Fig. 5 Concrete facings supported on ledges

Annexure 15-A.8

SPECIFICATIONS FOR EXTERNAL FACING AND VENEERS – WALL TILING AND MOSAICS

1 General - Wall tiles provide a wide range of architectural treatment for external rendering.  Generally the methods covered here for wall tiles and mosaics are applicable to the unit of an area not exceeding 900 cm2. Larger shapes and sizes of tiles and mosaics require special methods not covered herein.

2 Materials

Tiles, mosaics and other materials shall conform to the following:

a)  Terrazzo tiles shall conform to IS: 1237-1980.

b)  Ceramic glazed tiles shall conform to IS: 777-1988.

c)  Unglazed clay facing brick tile shall conform to IS: 2691-1988.

d)  Mosaics are of a variety of shapes and sizes.

e)  For mortar, cement shall be to IS: 269-1989 or IS: 455-1989 or IS: 1489 (Parts 1 & 2)-1991 or IS:  3466-1988 or any other as specified.  Lime shall conform to IS: 712-1984. Sand shall conform to IS:  2116-1980 for mortar bedding and to IS: 1542-1992 for floating coat and pointing.

3 Preparatory Work

a)  Sufficient time should elapse for complete initial drying and shrinkage of the background before application of floating coat. The surface shall be properly cleaned from dust and particles.

b)  The surface should not be allowed to dry after wetting before application of the floating coat.  The floating should keep pace with wetting and if necessary the surface shall be rewetted. Efflorescence of laitance shall be removed.

c)  To provide an effective key for surfaces contaminated with oil or grease special treatment by fixing a metal lath or wire netting shall be given.  At least one-half of any smooth surface shall be removed to a depth of 3 mm either by hand or mechanically.

Weak backgrounds, which are unlikely to support a floating coat should be covered with a firmly fixed metal lathing or wire netting.

d)  Movement of joints due to shrinkage of background and settlement of unit shall be provided for.  Normally, these joints shall be at the level of every storey height horizontally and every 3 m vertically. They shall coincide with structural material changes, such as, top of slabs for horizontal joint. Movement joint shall extend to depth of tile and bed and shall be minimum 6 mm wide. The joints shall be filled with cement mortar with about 15 per cent gauging with lime putty.

4 Application of floated coat for tiles and mosaics

a)  The purpose of floated coat or rendering is to form a surface suitable for application of tiling when the background is unsuitable for direct fixing of tiles.

b)  Mix for the floated coat shall be 1:3 cement mortar (volume) for smooth and moderately strong backgrounds, such as, high density bricks or blocks, precast or in-situ stone, etc. To improve workability and thus to aid application and finishing, a small portion of hydrated lime may be added to the mix ; for 1:3 cement mortar by volume, one-fourth lime by volume may be added.

c)  Thickness of each floated coat should not be more than 10 mm; the float shall be even and preferably scratched to provide a key for the bedding mortar.

d)  The mix for bedding can be sand cement mortar or sand cement mortar with additives; 1:4 mix should be adequate; additives can be plasticizer, waterproofing agents, etc.

5 Fixing of tiles

a)  Tiles are fixed beginning at the uppermost level working downwards to avoid disfiguring, staining damage and subsequent cleaning. The tiles with non-porous bodies need not be soaked; tiles with porous bodies should be completely immersed in clean water at least for an hour before using. After soaking, the tiles shall be stacked tightly on a clean surface to dry.

b)  The tiles should be fixed on the wetted floated coat, they should be tapped back firmly into position so that the bed is covered entirely by the tile. The thickness of bed should be between 6 to 12 mm after fixing the tile. Uniform spacing between tiles should be obtained by using spacer pegs as the work progresses. Any adjustment of the tile shall be made within about 10 min. Ensure that the surface of tiling shall be true and flat. Cleaning shall not be started before 1 ½ h after fixing.

c)  Grouting or pointing of tiles should not be carried out, until the day after the tiles have been fixed. A waterproofing agent may be added to the grouting mix.

The grout should be applied with a squeeze working back and forth over the area until all the joints are completely filled; all the surplus grout should be removed from the tiles and polished.

Pointing would be similar to grouting, except that a small portion of fine sand should be added to the mix.

6 Fixing of ceramic mosaics

a)  Mosaics shall be assembled in the form of sheets or varying mixes, the separate pieces of mosaic glued face down to any suitable material such as, paper, nylon, adhesive strips, etc. The paper strips,  etc should be easily removable after fixing has taken place. All dimensions be checked out so that no difficulty would arise in setting it out.  Where mosaic has to be applied to a floated coat, the surface shall be slightly scratched and finished with a wood float.

b)  The bedding mortar may be 10 mm thick.  Before bedding the mosaic, the fixing side of the mosaic sheet shall be grouted with neat cement slurry.

c)  After the sheets have been firmly beaten into the facing, paper and glue sheets removed and, the final straightening done, a grout shall be rubbed over the surface to fill the voids in the joints and then cleaned down. After the cement in the joints has hardened, the whole surface may be washed down with a solution of 10 percent hydrochloric acid and 90 percent eater and finally cleaned with water.

7 Fixing of marble mosaics - the fixing shall be the same as above in 4.6 with the exception that the back of the mosaics, after applying the cement grout into the joints, shall be covered with a layer of two parts of fine sand and one part of cement to the level of the thickness. This is due to the variation in thickness of marble slabs.

Annexure 15-A.9

SPECIFICATIONS FOR WALL COVERINGS

1 General - Wall coverings such as building boards, sheets, etc. are extensively used in construction of light partitions. They are also used on solid wall buildings to obtain various decorative finishes which are easier to install and maintain than traditional plaster and allied finishes. The selection of these boards depends on appearance and performance requirements, methods of fixing and joining, different types of boards, etc. The boards generally used are gypsum plasterboards and wall boards; fibre building boards, plywood and blackboard; chip boards particle boards; asbestos cement wall boards and multiple layer coverings.

2 Materials - The materials shall conform to the following Indian Standards:

a)  Boards

IS: 303-1989 : Common commercial plywood

IS: 710-1976: Marine plywood

IS 1328-1996: Veneered decorative plywood

IS: 7316-1974: Decorative plywood

b) Fixing Accessories

IS: 451-1999: Wood screws

IS: 459-1992: Asbestos sheets (corrugated)

IS: 723-1972: Nails

IS: 1658-1977: Fibre Building board

IS: 1659-1990: Block boards

IS: 2905-1982: Gypsum plaster board

IS: 2098-1991: Plain asbestos sheets

IS: 3087-1985: Particle board medium density

IS: 3097-1980: Particle board (veneered)

IS: 3129-1985: Particle board (low density)

IS: 3348-1965: Fibre insulation boards

IS: 3478-1966: Particle boards (high density)

IS: 5509-1980: Fire retardant plywood

3 Preparatory works

a)  The spacing of supports and fixing rigid wall coverings shall be as given in Table1 below.

b)  Joint thickness shall be of about 6 mm. All vertical joints shall be staggered, particularly where both sides of the wall are covered.

Table-1 Spacing for support and fixing of rigid wall boards

Sl. No.      

Type of Board

Thickness (mm)    

Spacing of supports

(mm)

Nail Spacing Centre to Centre

Minimum Edge Clearance of Nails

at edges

at supports

1

2

3

4

5

6

7

1

9.5

 

400

 

 

 

Gypsum board

12.5

500

100 to 150

100 to 150

10

15

600

2

Fibre building board, particle board, etc.

10

400

75

150 to 200

10

    12    

500

20

600

 

Plywood, black board, etc.       

6.9

400

150

300

10

12

500

16

600

 

Asbestos board

6

400

150 to 200

150 to 200

---

Note – Nails with shank diameter 2.00, 2.24 or 2.50 mm are commonly used.

5.4. Fixing of Boards

a)  Gypsum boards may be fixed as in Fig. 1. The joints may be filled with finishing material, such as, gypsum plaster or any other material recommended by the manufacturer. After filling the joints, a thick skin of finishing materials shall be spread 50 mm on either side of the joint and on to it shall be trowelled dry, a reinforced scrim cloth about 100 mm wide ; or the joints may be left open as desired.

b) For fibre building boards (see Fig. 2).  The boards shall be stored for 24 h before fixing. The studs and grounds for fixing shall be spaced as given in Table 1.  The joints may be open butt joint at least 3 mm wide. Various types of joints shall be as in Fig. 3

c)  Plywood, blackboard, etc., covering may be fixed as in Fig. 4. The edges of plywood shall be protected before fixing with a suitable sealer. The fixing may be done in panels; horizontal paneling may be done in bays not exceeding 2.7 m in length; vertical paneling may be done in bays not exceeding 0.9 to 1.2 m.  Joint for plywood and blackboard boards shall be as in Fig. 5 and Fig. 6 respectively.

d)  Particle boards may be fixed as in (c)

e)  Fixing asbestos cement board shall be as shown in Fig. 7 and Fig.8 for flat and corrugated sheets respectively.

f)  When multiple layers of coverings have to be done the first covering shall be fixed as in (a) to (e) above. Further covers shall be bonded by suitable adhesive to the first cover or as specified by the manufacturer.

For better strength and stability, successive boards may be fixed in perpendicular direction to the one below it, or if all the layers are fixed vertically, the joints of each layer shall not occur over the joints of the preceding layer.

Fig. 1 Fixing gypsum boards

Fig. 2 fixing fiberboard wall sheathing

Fig. 3 Details of fiberboard joints

Fig. 4 Fixing plywood wall sheathing

Notes

Edge sealing - Protect all the edges of the board using a suitable sealant or edge lipping to prevent moisture absorption.

Suggested sealant - For 6 mm ply Epoxy resin, nitrocellulose lacquer

Suggested lipping - Veneers - 1.5 mm thick, solid wood strips, P.V.C. bands, elastic laminates, aluminium strips.

Fig. 5 Details of plywood joints

Notes

Edge sealing - Protect all the edges of the board using a suitable sealant or edge lipping to prevent moist6ure absorption.

Suggested lipping - Veneers - 1.5 mm thick, solid wood strips, P.V.C. bands, elastic laminates, aluminimum strips.

Fir. 6 Details of block board joints.

Fig. 7 fixing flat asbestos

Fig. 8 Fixing corrugated asbestos cement sheets

Annexure 15-A.10

SPECIFICATIONS FOR CEILING COVERINGS

1 General - Coverings are fixed on to the ceiling to give decorative appearance, to conceal projections, such as beams occurring underneath floor slab, to provide a false ceiling, to obtain special acoustic effects, insulation against heat and cold, etc.

Fixing details using the following boards and others are covered herein:

a)   Insulated board: IS: 3348-1965

b)   Hardboard: IS: 1658-1977

c)  Plaster of Paris Ceiling &: IS: 2547(Parts 1 & 2)-1976

      Plaster of Paris tiles

d)   Gypsum plaster board: IS: 2095-1996

e)   Plywood and blackboard: IS: 303-1989, IS: 1328-1996 (Plywood)

: IS: 7316-1974, IS: 710-1976, IS: 1659-1900 (Block board)

f)   Asbestos cement building: IS: 2098-1997 (Plain) IS: 459-1992 board Corrugated)

g)  Wooden cover fillets for ceiling

h)  Cloth ceiling

i)  Aluminium sheet ceiling

j)  Expanded polystyrene ceiling

k)  Mineral wood board

The fabrication and fixing of timber ceiling is covered by IS: 5390-1984.

2 Preparatory work

a)  Wooden or metal framework, consisting of longitudinal bearers and cross bearers by means of which the ceiling board are supported, shall be designed for structural strength and stability as per IS:  883-1994.

b)  The suspenders from RCC slabs for supporting the framework for false ceiling shall be of sufficient length to reach the ceiling frame.

c)  Ceiling boards, less than 5 kg/m2 in mass, can be directly fixed to RCC by means of fixing plugs, bolts, etc.

d)  Where double ceiling boards are provided, such as, in air conditioning installations, cold storage rooms, the first layer of ceiling board may be fixed to the ceiling with plugs or other fixing devices in the concrete slabs at required spacings.

e)  Typical details of framework and methods of its suspension are shown in Fig.1 and Fig.2

Fig. 1 Details of ceiling frame suspended from RCC slab

Different methods of attachment of hangers to top members are illustrated in A,, B,C and G and to ceiling frames are illustrated in A,C,D,F and G.

Use of clips, studs and hooks for fixing bolts are illustrated in H and E

Fig. 2 Details showing some typical methods of suspension of ceiling frame from structural members.

3 Fixing of coverings

3.1 Insulating building board

a)  Materials – The timber for framework and beading shall be treated and chosen from any of the species in IS: 3629-1986. Insulating building boards may be particle boards (low density) to IS: 3129- 1985 or fibre insulating boards to IS: 3348-1965. Nails, conforming to IS: 723-1972 shall be long enough to cover the thickness of board plus 25 mm. Galvanized lost head nails to IS: 6738-1972 of 2.80 mm dia may be used when joints are left exposed. Where joints are to be covered by beading, galvanized felt nails of 2.50 mm dia conforming to IS: 6730-1972 may be used. Wood screws shall conform to IS: 6760-1972.

b)  Fixing – Cut the boards to the required size.  The edges shall be slightly sand papered to make them smooth. The framework with battens, size ranging from 60 to 75 mm shall then be fixed. Aluminium frame may also be used instead of timber frame. The building board shall then be fixed with lengths parallel to all joints centered over the framing members. Where the joints are to be covered the boards shall be spaced 3 to 6 mm apart. Where the joints are to be exposed the sheets shall be butt jointed with their edges abutting each other. The boards are first nailed to intermediate framing member proceeding from the centre of the board outwards, the edges being nailed last.

1)  Where joints are exposed, the outer row of nails shall be at 100 mm centres and about 12 mm from edge of the sheet. The rows in the middle of the sheet shall be at 20 mm centres. Nails in the outer rows on either side shall be paired and not staggered. Nails shall be countersunk in the underside of the board.

2)  Where joints are to be covered with beading, the procedure is the same as in (1) above, except that in the outer rows, the nail spaced at 200 mm may be staggered. The beadings shall then be fixed over the sheets with screws at 200 mm centres.

3)  The exposed side shall be truly level; joints truly parallel and perpendicular to the walls.

3.2 Hardboard

a)  Materials – Timber shall conform to IS: 5390-1984. The hardboard shall conform to IS: 1658-1977.  The other materials shall be as per 3.1 (a).

b)  Fixing

1)  The framework and board shall generally be fixed.  Wood screws may be used.

2)  The joints may be normally filled with plaster. If the hardboard has to be cement plastered the joints shall have a gap of 6 mm covered with scrim and bedded in cement plaster before the finishing coat is applied.

3)  The finishing shall be as in 6.3.1. (b) (3).

6.3.3 Plaster of Paris

a)  Materials – Timber for framing shall conform to IS: 5390-1984. Plaster of Paris shall conform to

IS: 2547 (Parts 1 and 2)-1976. The other materials shall be as in 6.3.1. (a).

b)  Fixing

1)  In case of sloping roofs, wooden battens of suitable section (50 mm x 60 mm) shall be firmly fixed as main supports, to the underside of the beams at required centres by means of bolts and nuts. In case of flat roofs, treated battens shall be securely fixed to the walls and pillars by holding down bolts and shall be fastened to the slabs above with iron straps or mild steel bars anchored therein. Cross battens (treated) of 50 mm x 40 mm at about 400 mm centres shall then be fixed at right angles to the main battens.  The underside of the framework shall be true to planes and slopes.

Aluminium frame may also be used if specified.

2)  Wooden strips or laths 25 mm x 6 mm shall be fixed to the cross battens in parallel rows with felt nails. The strips shall be butt jointed and joints staggered.

3) Rabbit wire mesh shall be fixed with rails of a pitch of 150 mm to 200 mm to the underside of wooden strips. The wire mesh shall be straight, tight and true to planes and slopes without any sagging and slightly below the underside of the laths.

4)  Plaster of Paris shall be mixed with water to a workable consistency. The plaster shall be applied to the underside of laths over the rabbit wire mesh in suitable sized panels and finished to a smooth surface by steel trowels. The thickness over the laths shall be as specified but not less than 12 mm. Joints shall be finished flush ; the surface shall be smooth and true to plane, slope or curve as required.

3.4 Plaster of Paris tiles

a)  Materials – Timber for making framework shall be from any species in IS: 5390-1984. Plaster of Paris shall conform to IS: 2547 (Parts 1 and 2)-1976; thickness of tiles shall be not less than 12 mm. Hessian cloth shall conform to IS: 2818(Part 1)-1990; Hessian cloth shall be of an open webbed texture.

b)  Preparation of tiles – Tiles of plaster of Paris reinforced with Hessian cloth shall be prepared to the required size. The maximum size shall be limited to 750 mm in each direction. The tiles may be made on a glass sheet with wooden surrounds; a thin coating of non-staining oil may be given to the glass sheet for easy removal of tiles. Plaster of Paris shall be evenly spread to about half the thickness and then Hessian cloth spread over it, on this, plaster of Paris is spread again to the full thickness. Tiles shall be allowed to set for an hour and then removed to dry and harden for about a week.  A good tile will give a ringing sound when struck.

c)  Fixing – The timber frame shall be so made that each tile has supporting scantlings to fix them. Aluminium frame may also be used. Tiles may be fixed to the cross battens with 40 mm long brass screws to IS: 6760-1972 at 200 mm centres. Tiles may be laid adjacent to each other without leaving any gap. The screws shall be at least 15 mm away from the edge. Holes for screws shall be drilled. The countersunk heads of screws shall be covered with plaster of Paris and smoothly finished. When unbroken surface is desired, joints shall be filled with plaster of Paris and toweled smooth.

3.5 Gypsum plaster board

a)  Materials – The boards shall conform to IS: 2095-96. Nails shall conform to IS: 723-1972. The length of the nails shall be 30 mm for boards 10 mm thick and 40 mm for 12.5 mm or 16 mm thick boards. Screws shall conform to IS: 6730-1972. Steel screws without brass or nickel coating shall not be used. Screw sizes shall be 3.10 or 3.45 mm; length shall be 30 mm for 10 mm thick board and 35 or 40 mm for 12.5 mm and 16 mm board.

b)  Fixing – The frame work shall be fixed as in 3.1 (b). Joints may be 6 mm wide.  Jointing may be in a decorative pattern. The joints may be finished with a filling of gypsum plaster or other materials; after filling the joint, a thick skin of the finishing material shall be spread 50 mm on either side and toweled dry. When metal scrim is used, a stiffer plaster may be necessary. The joints may also be left open if desired.

3.6 Plywood and block board

a)  Materials – Timber for framework shall conform to IS: 5390-1984. Plywood shall conform to IS:  303-1989 or IS: 710-1976 or IS: 7316-1974 or IS: 1328-1982 or IS: 5509-1980.  Block board shall conform to IS: 1659-1990, screws shall conform to IS: 6760-1972.

b)  Fixing - The fixing shall be as in 6.3.1. (b) ; except that for boards in thickness 4 to 10 mm the spacings may vary from 450 to 600 mm for longitudinal battens and 600 to 1200 mm for cross battens ; for boards above 10 mm thick, the spacings may be 600 to 900 mm for longitudinal battens and 900 to 1300 mm for cross battens.  The spacing of fixing countersunk screws may be adjusted according to thickness of board. Joints if left out open shall be filled with painters putty and brought to level ; joints may also be left open. The joints may be rebated or tongue and grooved.

The ceiling shall be finished by hand-sanding and waxed or polished or clear varnished or painted as required (see section 15).

3.7 Asbestos cement building board

a)  Materials – Timber for framework can be any of the species in IS: 5390-1984; asbestos board shall conform to IS: 2098-1964; screws shall conform to IS: 6730-1972.

b) Fixing – Framework shall be fixed. The asbestos board shall be laid truly parallel or perpendicular to the walls and shall be fixed to the battens with countersunk screws by using metal channels and clips. Holes shall be drilled at least 12 mm from edge. They should be butt jointed.  If a gap of 3 to 6 mm between sheets is given the gap should be covered with wooden beading or similar material.

No finishing treatment is necessary.

3.8 Wooden cover fillets beading

a)  Materials – Timber for framework may be any of the species of IS: 5390-1984. Screws shall conform to IS: 6730-1972. Beading shall be planed, smooth and true on the rear surface. It may be 12 mm x 40 mm or as specified.

b)  Fixing – The beading shall be fixed centrally over the butt joints between two timber planks with screws in two rows on either side of joint.

The junction of beading shall be fully mitred or as specified. The beadings shall be finished smooth.

3.9 Cloth

a)  Material – Timber for framework shall be as per IS: 5390-1984. Bamboo of good quality may be used for framework. In general thick cloth can be used or a specified. Screws shall conform to IS:  6730-1972 and nails to IS: 723-1972.

b)  Fixing –  The framework shall be securely spiked to the wall plaster/ceiling joints or beams. The cloth shall be wetted, stretched and nailed to the upper side of the framework. In case of bamboo framework, the cloth shall be tied to it without tearing. To prevent the cloth from blowing and flapping, wooden beadings shall be fixed.  The cloth may be white washed and distempered.

3.10 Aluminium sheet

a)  Materials – The framework may be made of aluminium ‘T’ grid and trays of aluminium alloy sheets 19000 or 31000 of IS: 737-1986. The grid shall be made of extruded aluminium ‘T’ section of 63400 or Wp of IS: 733-1983. The fillings shall be made out of aluminium or rust proofed steel.

b)  Fixing – The ceiling may be formed as an exposed grid or a concealed grid using the above sections. The aluminium false ceiling may be left as it is if anodized or painted with acrylic resin paint.

3.11 Expanded polystyrene

a)  Material – Expanded polystyrene shall conform to IS: 4671-1984.  Screws shall conform to IS:  6730-1972. The framework may be of wood or metal.

b) Fixing – Adhesive shall be applied to the tiles and fixed to the framework. The white polystyrene ceiling may be painted as specified.

3.12 Mineral wood board

a)  Materials – Timber for ceiling shall be from IS: 5390-1984; nails to IS: 723-1972, screws to IS:  6730-1972 and mineral wood to IS: 3677-1985.

b)  Fixing – A metal ‘T’ grid shall be suspended first and mineral wood board may be cut to size and stuck with suitable adhesive.  For timber framework, the mineral wool board shall be stuck with an adhesive. Similar procedure may be followed with local modifications, as necessary, for different ceilings.

4 Fixing devices

4.1 Types

The fixing devices covered are as below

a)  Expansion wall plugs,

b)  Expansion shells,

c)  Caulked-in anchor devices, and

d)  Butt-in devices.

4.2 Fixing - Proper devices and tools ensure a neat fixing work with minimum effort and little damage, and the fixtures will have adequate strength and durability. Special devices are also available for resisting dampness, chemical attack, thermal effects, etc. Details of fixing devices are given in IS:  1946-1961.

Fixing devices, mentioned above are for solid walls. Devices for hollow walls are also coming into vogue.

Note Since the date of publication of this standard several new innovations have been introduced; the trade may be consulted for more information.

Annexure 5-A.11

SPECIFICATIONS FOR FABRICATION AND FIXING OF TIMBER CEILING

1 Construction of timber ceilings

1.1 General – Timber ceilings are provided to give decorative appearance, to conceal air-conditioning or other service ducts and also to obtain acoustic effects and thermal insulation.

1.2 Material – Timber for making planks shall be from any of the species given in Table 1 and the ceiling framework and beading shall conform to IS: 3629-1966 appropriately seasoned and treated. Nails shall conform to IS: 723-1972 and the wood screws to IS: 451-1972. Suspenders may be mild steel flats or other material sections.

The dimensions of timber units for ceiling may be as below

1) Timber scantling for ceiling and framework : 60-75 mm thick x 50 mm wide

2) Timber planks : 15-20 mm thick x 100-150 mm wide

3) Beading : 12 mm thick x 30 mm wide

1.3 Types

a)  Fixing Ceilings – Planks shall be butt and beading jointed or overlap or half lap or tongued and grooved.

b)  Sloping Ceilings – The ceiling shall be fixed to the underside of rafters.

c)  Closed Ceiling – The ceiling shall be fixed to the underside of the ceiling joists.

d)  The planks shall be fixed to the timber frame suspended from the slab. The surface of finished ceiling shall be true and plane.

Table 1 Species for timber ceilings (Clause 1.2)

Anjan

Jarul

Machilus

Teak

Axlewood

Karl

Maniagwa

White Cedar

Bijasal

Kalasiris

Pali

White Chuglam

Chir

Kasi

Piney

 

Cypress

Kindal

Rohini

 

Deodar

Kokko

Rosewood

 

Fir

Laurel

Satinwood

 

Gurjan

Lendi

Sisoo

 

 Annexure 15-A.12

SPECIFICATIONS FOR CONSTRUCTION OF TIMBER WALLING

1 General:

Walls and partitions of the following types are covered herein;

a)  Reed Walling to IS: 4407-1967,

b)  No fines in-situ to IS: 12727-1989, and

c)  Gypsum block partitions to IS: 3630-1992.

2 Reed walling

2.1 General – Reed walling is a traditional construction in certain parts of India ; in Assam EKRA and NAL are used ; in Punjab SARKANDA reed is used. In addition machine made reed boards are also used. In these boards, reeds are considerably strengthened by binding together with galvanized wire. Reed walling and roofing have advantages like thermal insulation and light weight and are found specially suited for earthquake resistant construction, where flexible light weight material is needed for walling.  Use of reed walling will facilitate additional advantages of prefabricated construction particularly suited for panel filling, partitions and roof construction.

2.2 Materials – Reed boards, made by binding reeds with galvanized wire, are available in three different thicknesses of 2.5 cm, 4 cm and 5 cm, preferred widths are 1 m and 2 m. The boards are generally used as below:

Component        Thickness

For door and window aneling, for wall facing, for Partitions and for ceiling

2.5 cm thick

For sloping and gabled roof, for weather board partition Walls, for fencing, for wall insulation, etc.

4 cm thick

For panel walls of exterior use, for sloping and gabled roofs, for weather boards, etc.

5 cm thick

The spacing of purlins for roof shall not be more than 0.5 m centres.

The reeds may be EKRA, KHASRA, NAL, and SARKANDA. These reeds shall be cut from mature plant, which have their sheaths firmly attached; they shall be dried in the sun.

2.3 Preparatory work

Cutting of reed boards – Cutting of reed board shall be done as follows;

a)  Cut each running wire half way between the required hook wire and the next one as in Fig. 1. After each running wire is cut, bend the ends tightly over the respective hooks. Remove the reeds which are left between two hook wires exposing the running wire on the underside of the board.

b)  Place the boards erect and cut the running wire on the other side and bend the cut ends over the hook wire.

c)  Cutting across the reed may be done with the use of a saw or a sharp broad chisel.  Cutting shall not be done near the wire and at least 25 mm of the board shall be left to cover as edge beyond the running wire.

d)  For cutting diagonally or in shapes combine the two methods in (a) and (c).

4 Joining the reed boards – With the reeds vertical, the joining shall be done as in Fig. 2

5 Fixing of reed board

a)  Fixing of partitions – Reed boards shall be fixed with reeds vertical to horizontal runner spaced at 1 m centres. The adjacent boards shall be butt jointed and the joint shall be located at the centre. Fixing shall be done with wood screws with a spacing of 30 cm. While fixing to frames, boards shall not be fixed into a groove. While locating the door and window openings, work should be carefully planned so as to keep cutting and wastage to a minimum.

The board of window sill shall be so cut that it covers half the frame runners on all sides (see Fig. 3)

b)  For roof construction, reed board shall be used for pitched roof as in Fig. 4 and not flat roof.

6 Fixing of reeds for in-situ wall construction

a)  Grooves, 15 mm wide shall be made in the timber frame and the reeds slipped into the grooves one by one. The reed walling may be stiffened by means of double bamboo slips 25 mm wide and not less than 6 mm thick spaced at around 40 cm apart. One slip shall be attached to each side of the reed and tied together.  Reeds may be fixed with just sufficient space of 1 cm between each other so that the mortar may be applied on one side for finishing so that it penetrates to the other side to form a key for plaster. All vertical timbers in walling shall have grooves (4 cm x 1.5 cm deep) to force plaster into it.

b)  The reeds shall not be used for roofing, without making them into boards.  Reed may, however, be used for thatching.

7 Finishing

Reed boards may be pebble- dash plastered or rough cast finished after fixing. Reed boards should be dry before applying plaster. The mix shall generally be cement mortar 1:6 applied in two coats not more than 15 mm, lime plaster mix may be 1:3 using class C lime of IS: 712-1984 ; mud plaster specified. Waterproofing may be done using bitumen felts.  The reed walling may also be painted it required.

Fig. 1 Operations for cutting of reed board

Fig. 2 Details of joining of reed board

Fig. 3 Details of construction for the reed walling at the sill of windows 

Fig.4. Seed board ridging for roof

Annexure 15-A.13

SPECIFICATIONS FOR GYPSUM BLOCK PARTITIONS – NON-LOAD BEARING

1 General – Gypsum block partitions are light in weight, fireproof and free from pest infestation. There is a scope for large scale use in multistoried construction. They are not suitable for external use.

2 Materials

a)  Gypsum block shall conform to IS: 2849-1983 for both solid and hollow blocks. The surfaces of the block shall be smooth or scored ; the scoring shall not be more than 5 mm deep.

b)  Mortar shall consist of one part gypsum and three parts fine aggregate conforming to IS 383 – 1970 or sand by weight ; sodium citrate in proportion of 0.25 per cent of the weight of gypsum may be added as a retarder. For fine work, that is, work with fine mortar joints, the mortar may also consist of gypsum and lime in the ratio of 1:3 by weight with 0.25 percent of sodium citrate.

c)  Reinforcing material may be mesh, expanded metal tiles, light gauge expanded metal, steel strips, etc.

3 Laying of block

a)  Gypsum block partitions shall not be wetted before laying, however the surfaces in contact with mortar may be wetted, to reduce suction, with minimum quantity of water.

b)  Gypsum block partitions shall be built in half bond in true level and regular courses (see Fig. 1).

c)  The joints shall be as thin as possible. Where the partition is to be plastered, the joints shall be left roughly flush or may be raked out.

d)  Where possible, frames for openings shall extend from floor to ceiling to secure a positive fixing at both ends ; they shall have a groove to receive the ends of blocks.

e)  Gypsum block lime 0.5 m wide may span the openings. The lintel blocks may span in an arch form also (see Fig. 2).

f)   At the ceiling the partition shall be secured and isolated with wedges as in Fig. 3

g)  Cracking in partitions takes place due to variations in volume of blocks; this can be taken care of as in Fig. 4

h)  Vertical joints may be reinforced as in Fig. 1

For strength and stability purposes the height of partition shall be limited to 36 times the thickness of block ; except when lateral support is provided it shall not exceed 72 times the thickness.j)  The block may be finished with a rendering of gypsum plaster not less than 6 mm thick ; otherwise it may be left as it is but cleaned down and any defects made good with neat gypsum plaster with mortar.

Note : Number of reinforcement bars will depend on number of holes in the block

Fig. 1 Reinforcing of vertical joints of gypsum blocks as a safe guard against crackin

Fig. 2 Reinforcement around opening in gypsum block partitions

Fig. 3 Position of wedge and gypsum block partition wall above skirting

Fig. 4 Methods of edge isolation for partitions

Annexure 15-A.14

SPECIFICATIONS FOR NO-FINES CONCRETE

1 General – No-fines cement concrete has highly permeable mass with large air spaces. It is an agglomeration of coarse aggregate particles each surrounded by a coating of cement paste, up to about 1.25 mm thick. As the aggregate to be used is almost single sized, resulting in formation of enough voids and therefore light in weight and eliminates the rise of dampness. No-fines can be used in walls, foundations where elimination dampness is desirable.

No-fines cement concrete can substitute brick masonry where good bricks are not available. Further the thermal conductivity of wall made from a no-fines concrete with conventional aggregate and a solid brick wall  of the same thickness is about the same.

2 Materials

a)  Cement shall conform to IS: 269-1989 or IS: 1489 (Parts 1 & 2)-1991 or IS: 455-1989 and IS: 8041-1990 or any other as specified.

b)  Aggregate should conform to IS: 383-1970; the aggregate would be nominally graded from 40 mm to 20 mm. Whichever size is used, the proportions of oversized and undersized material shall be kept as low as possible ; generally oversize and undersize material should not be used more than 5 percent and 10 percent respectively.

c)  Brick ballast may be used preferably broken at site; no unburnt bricks shall be used. Stone ballast may be used with a flakiness index of less than 15 percent.

3. Mixes

The no-fines concrete mixed shall be as in Table below for guidance.

Strength of various no-fines concrete mixes

Sl No.

Maximum size of ballast

Mix by volumes (Cement :  Aggregate)

Water cement ratio (Optimum)

Expected compressive strength in 28 days N/mm2

1

20

1:8

0.40

5.5

2

20

1:9

0.42

4.9

3

20

1:10

0.45

3.5

4

20

1:12

0.48

3.5

5

40

1:10

0.48

3.5

6

40

1:12

0.50

2.6

4 Transporting, placing, compacting, curing, and workmanship – Concrete shall be transported by methods which will prevent segregation or loss of any of the ingredients. In hot or cold weather it shall be transported in deep containers, adopting suitable methods to prevent loss of moisture.

The concrete should be poured in horizontal layers. Care shall be taken to ensure that the ballast is uniformly coated with cement layer.  Thickness of concrete placed in a wall should not exceed 500 mm; minimum thickness may be 230 mm.

Concrete shall not be vibrated for compaction; compaction may be done by rod or gentle ramming. No water should be added during ramming.

Curing shall be done by spraying water at least for 7 days.

5 Workmanship

a)  Construction joints in walls – Vertical or raking construction joints shall not be permitted except where expansion joints are to be formed. Horizontal joints should be as few as possible. Cracks due to shrinkage and setting can be avoided by locating expansion joints at 30 m interval.

b)  Wall ties may be used between floors and walls throughout the building. Cracks may be avoided at openings by placing two 10 mm dia mild steel under the window sill. Concrete cover should be 50 mm minimum.

c)  It is impractical to nail into no-fines concrete. Therefore for fixing, fixing devices should be incorporated before pouring concrete; or holes, etc, should be formed by finishing suitable towards the shuttering for services.

d)  Plastering can be done on both internal and external surfaces; the thickness may be 10 mm to 12 mm in two layers.

Annexure 15-A.15

SPECIFICATIONS FOR DRESSING OF NATURAL BUILDING STONES

(Extract of IS: 1129-1972)

1. Scope

1.1 This standard lays down the recommendation for the requirements of various types of hand dressing of natural building stones. 

2. Types

2.1 Pitched faced dressing – The edges of a pitched faced dressed stone shall be level and shall be in the same plane being absolutely square with the bed of the stone.  Superfluous stone on the face shall be allowed to remain there and left raised in the form of a natural rounded cobblestone.  The minimum width of pitched-faced dressing round the four edges of the face of the stone shall be 25 mm.  The appearance of pitched face stone is as shown in Fig.1.

Fig 1 Pitched faced dressing surface

2.2 Hammer dressing – A hammer dressed stone shall have no sharp and irregular corners and shall have a comparatively even surface so as to fit well in masonry.  Hammer dressed stone is also known as hammer faced, quarry faced and rustic faced.  The appearance of hammer dressed stone is as shown in Fig.2.  The bushing on the face shall not be more than 40 mm on an exposed face.

Fig 2 Hammer dressed stone surface

2.3 Rock facing – A stone which has been dressed in this manner shall have a minimum of 25 mm wide fine chisel marks at the four edges, all the edges being at the same plane.  Stones of this type are used in buildings as quoin stones in the corners of brick masonry or rubble masonry and in plinth to give an appearance of strength and solidity.  The appearance of rock faced stone is as shown in Fig.3.

Fig 3 Rock faced stone surface

2.4 Rough tooling – A rough tooled surface shall have series of bands, 4 to 5 cm wide, more or less parallel to tool marks all over the surface.   These marks may be either horizontal, vertical or at an angle of 450 as required (see Fig.4).  The edges and corners shall be rendered square and true.  The dressed stone may have depressions on the surface.  The depth of gap between the surface and a straight edge held against the surface shall not be more than 3 mm.  Rough-tooled stones are used where fairly regular plane faces are required for masonry work.

Fig 4 Rough tooled stone surface

2.5 Punched dressing – A rough tooled surface is further dressed to show series of parallel ridges.  Chisel marks shall be left all over the surface.  The depth of gap between the surface and a straight edge held against the surface shall not exceed 3 mm.  Punched dressed stones are used where even surfaces are required (see Fig.5).

Fig 5 Punched stone surface (chisel drafted)

2.6 Closed picked dressing – A punched stone is further dressed so as to obtain a finer surface, ridges or chisel marks left over being very tiny.  The depth of gap between the surface and a straight edge kept over the surface shall not exceed 1.5 mm (see Fig.6).

Fig 6 Closed picked stone surface

2.7 Fine tooling – Closed picked surface is further dressed so that all the projections are removed and a fairly smooth surface is obtained.  The surface shall have 3 to 4 lines per centimeter width depending on the degree of hardness of stone and degree of fineness required.  This type of dressing is very commonly adopted for ashlar work.  A sketch of fine-tooled surface is shown in Fig.7

3. Procedure

3.1 Pitched faced dressing – When the stone is received from the quarry face, it shall be dressed along all the edges of its face by means of a mason’s hammer or club hammer and the pitching tool so as to obtain the finish described in 2.1.

Fig 7  Fine tooled stone surface

3.2 Hammer dressing – All the sharp and irregular corners of the stone obtained by blasting or splitting shall be knocked off by using the flat face of a scabbling or spalling hammer.  With the pointed end of the hammer the surface shall be then dressed.

3.3 Rock facing – All the sharp and irregular corners of the stone shall be knocked off by using the flat face of a scabbling hammer.  The exposed faces shall be then dressed as described in 3.3.1.

3.3.1 The superfluous stone along one edge AB (see Fig.3) shall be knocked off with a drafting chisel and a hammer until is coincides with a straight edge throughout its whole length.  This is known as chisel draft.  Further chisel drafts shall now be made along BC, CD and DA, so that the four corners are at the same level.  Diagonal drafts along BD and AC may be resorted to in the case of large stones to suit requirements.  Some of the superfluous stone in the centre, which is left, raised and rough to imitate a rock like surface shall be removed with the pitching tool or the scabbling hammer.

3.4 Rough tooling – The stone received from the quarry is hammer dressed.  Then the surface of the stone shall be dressed removing the top layer of about 0.3 cm thick by means of a plane chisel or a boaster and a mason’s or club hammer, by forming a series of 4 to 5 cm wide bands of more or less parallel tool marks which covers the whole surface.  These marks may be either horizontal, vertical or at an angle 450 as required, and in making them the boaster or chisel shall be moved in the direction of the band at each stroke.  The surface shall be tested now and then with a mason’s square for the requirements given in 2.4.

3.5 Punched dressing – Depressions are formed on the rough surface of the stone in rough tooling with a punch chisel and a mason’s or club hammer at close intervals and to a depth of about another 3 mm to form a series of parallel ridges.  The stone shall be checked with a straight edge for the requirement given in 2.5.

3.6 Closed picked dressing – a punched stone is further dressed with a pointed chisel and mason’s or club hammer by forming small pits of about 3 mm deptj to obtain a finer surface, the ridges or chisel marks left over being tiny.  The stone shall be checked with a straight edge for the requirement given in 2.6.

3.7 Fine tooling – the stone received from the quarry shall be closed picked and then fine tooled with a serrated or claw chisel and a mason'’ or club hammer.  By this operation all the projections caused in the earlier stages shall be removed and a fairly smooth surface obtained.  The finish shall conform with the description given in 2.7.

4. Finishing

4.1 Dragging or combing – After the surface of the stone has been brought to the required level by means of a dummy and soft stone chisel, the coarse drag is dragged backwards and forwards until the tool marks are eliminated.  This may be followed by second drag and fine drag according to the degree of evenness required.

4.2 Polishing

a) Polishing of stones shall be done by rubbing them with a suitable abrasive, wetting the surface, where necessary, with water.

b) Alternatively, polishing of stones shall be done by holding them firmly on the top of revolving table to which some abrasive material like sand or carborundum is fed.  The final polishing shall be performed by rubber or felt, using oxide of lime called by trade as ‘putty powder’, as polishing medium.

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