ROOFING WORK



ROOFING WORK

8.1. SPECIFICATIONS FOR CORRUGATED GALVANIZED STEEL SHEET ROOFING (See Fig.1)

8.1.1. Sheets - These shall be of the thickness specified in the description of the item and shall conform to IS: 277.  The sheets shall be of 750 grade of coating unless otherwise specified in the description of item.

Fig. 1 C.G.S. sheets

The sheets shall be free from cracks, split edges, twists, surface flaws etc.  They shall be clean, bright and smooth.  The galvanizing shall be non-injured and in perfect condition.  The sheets shall not show signs of rust or white powdery deposits on the surface.  The corrugations shall be uniform in depth and pitch and parallel with the side.

Purlins Purlins of the specified material or M.S rolled sections of requisite size shall be fixed over the principal rafters.  These shall not be spaced at more than the following distances.

Thickness of C.G.S. sheet

Maximum spacing of purlins

1.60 mm

2.80 metre

1.25 mm

2.40 metre

1.00 mm

2.00 metre

0.80 mm

1.80 metre

0.63 mm

1.60 metre

The top surfaces of the purlins shall be uniform and plane.  They shall be painted before fixing on top.  Embedded portions of wooden purlins shall be coal tarred with two coats.

8.1.3. Slope - Roof shall not be pitched at a flatter slope than 1 vertical to 5 horizontal.  The normal pitch adopted shall usually be 1 vertical to 3 horizontal.

8.1.4. Laying and fixing

The sheets shall be laid and fixed in the manner described below, unless otherwise shown in the working drawings or directed by the engineer.

The sheets shall be laid on the purlins to a true plane, with the lines of corrugations parallel or normal to the sides of the area to be covered unless otherwise required as in special shaped roofs.

The sheets shall be laid with a minimum lap of 15 cm at the ends and 2 ridges or corrugations at each side.  The above minimum end lap of 15 cm shall apply to slopes of 1 vertical to 2 horizontal and steeper slopes.  For flatter slopes the minimum permissible end lap shall be 20 cm.  The minimum lap of sheets with ridge, hip and valley shall be 20 cm measured at right angles to the line of the ridge, hip and valley respectively.  These sheets shall be cut to suit the dimensions or shapes of the roof, either along their length or their width or in a slant across their lines of corrugations at hips and valleys.  They shall be cut carefully with a straight edge chisel to give a smooth and straight finish.

Lapping in C.G.S. sheets shall be painted with a coat of approved steel primer and two coats of painting with approved paint suitable for G.S. sheet, before the sheets are fixed in place.

Sheets shall not be generally being built into gables and parapets.  They shall be bent up along their side edges close to the wall and the junction shall be protected by suitable flashing or by a projecting drip course, the later to cover the junction by at least 7.5 cm.

The laying operation shall include all scaffolding work involved.

Sheets shall be fixed to the purlins or other roof members such as hip or valley rafters etc. with galvanised J or L hook bolts and nuts, 8 mm diameter, with bitumen and    G.I. limpet washers or with a limpet washer filled with white lead as directed by the engineer. While J hooks are used for fixing sheets on angle iron purlins, and L hooks are used for fixing to R. S. joists, timber or precase concrete purlins.  The length of the hook bolt shall be varied to suit the particular requirements.  The bolts shall be sufficiently long so that after fixing they project above the top of the nuts by not less than 10 mm.  The grip of J or L hook bolt on the side of the purlin shall not be less than 25 mm.  There shall be a minimum of three hook bolts placed at the ridges of corrugations in each sheet on every purlin and their spacing shall not exceed 30 cm.  Coach screws shall not be used for fixing sheets to purlins.

The galvanized coating on J or L hooks, and bolts shall be continuous and free from defects such as blisters, flux stains, drops, excessive projections or other imperfections which would impair serviceability.

The galvanised coating should conform to IS: 1367 (Part XIII).

Where slopes of roofs are less than 21.5 degrees (1 vertical to 2.5 horizontal) sheets shall be joined together at the side laps by galvanised iron bolts and nuts 25 x 6 mm size, each bolt provided with bitumen and a G. I. limpet washer or a G. I. limpet washer filled with white lead.  As the overlap at the sides extends to two corrugations, these bolts shall be placed zig -zag over the two overlapping sheets shall be drawn tightly to each other.  The spacing of these seam bolts shall not exceed 60 cm along each of the staggered rows.  Holes for all bolts shall be drilled and not punched in the ridges of the corrugations from the underside, while the sheets are on the ground.

8.1.5. Wind tie - Wind ties shall be of 40 x 6 mm flat iron section or of other size as specified.  These shall be fixed at the eaves of the sheets. The fixing shall be done with the same hook bolts which secure the sheets to the purlins.  The ties shall be paid for separately unless otherwise described in the item of roofing.

8.1.6. Finish - The roof when completed shall be true to lines and slopes and shall be leak proof.

8.1.7. Measurements

8.1.7.1. The length and breadth shall be measured correct to a cm.  Area shall be worked out in sqm

correct to two places of decimal.8.1.7.2. The superficial area of roof covering shall be measured on the flat without allowance for laps and corrugations.  Portion of roof covering overlapping the ridge or hip etc. shall be included in the measurements of the roof.

8.1.7.3. Roof with curved sheets shall be measured and paid for separately.  Measurements shall be taken on the flat and not girthed.

8.1.7.4. No deduction in measurement shall be made for opening up to 0.4 sqm and nothing extra shall be allowed for forming such openings. For any opening exceeding 0.4 sqm in area, deduction in measurements for the full opening shall be made and in such cases the labour involved in making these openings shall be paid for separately.  Cutting across corrugation shall be measured on the flat and not girthed.  No additions shall be made for laps cut through.

8.1.8. Rate - The rate shall include the cost of all the materials and labour involved in all the operations described above including a coat of approved steel primer and two coats of approved steel paint on overlapping of C.G.S. sheets.  This includes the cost of roof sheets, galvanised iron J or L hooks, bolts and nuts, galvanised iron seam bolts and nuts, bituminous and galvanised iron limpet washers etc.

8.2. SPECIFICATIONS for ridges and hips of plain galvanised steel sheets

8.2.1. Ridges and hips - Ridges and hips of C.G.S. roof shall be covered with ridge and hip sections of plain G. S. sheet with a minimum lap of 20 cm on either side over the C.G.S. sheets. The end laps of the ridges and hips and between ridges and hips shall also be not less than 20 cm.  The ridges and hips shall be of 60 cm overall width plain G. S. sheet, 0.6 mm or 0.8 mm thick as given in the description of the item and shall be properly bent in shape.

8.2.2. Fixing

Ridges shall be fixed to the purlins below with the same 8 mm dia G. I. hook bolts and nuts and bitumen and G. I. limpet washers which fix the sheets to the purlins.

Similarly, hips shall be fixed to the roof members below such as purlins, hip and valley rafters with the same 8 mm  dia. G. I. hook bolts and rust and bitumen and G. I.  Limpet washers which fix the sheets to those roof members. At least one of the fixing bolts shall pass through the end laps of ridges and hips, on either side.  If this is not possible extra hook bolts shall be provided.

The end laps of ridges and hips shall be joined together by galvanised iron seam bolts 25 x 6 mm size each with a bitumen and G. I. washer or white lead as directed b y the engineer.  There shall be at least two such bolts in each end lap.

Surface of C.G. I. sheets of ridge and hip sections and the roofing sheets which overlap shall be painted with a coat of approved primer and two coats of approved paint suitable for painting G. S.. Sheets before they are fixed in place.

8.2.3. Finish - The edges of the ridges and hips shall be straight from end to end and their surface should be plane and parallel to the general plane of the roof.  The ridges and hips shall fit in squarely on the sheets.

8.2.4. Measurement - The measurements shall be taken for the finished work in length along the centre line of ridge or hip, as the case may be, correct to a cm.  The laps in ridges and hips and between ridges and hips shall not be measured.

8.2.5. Rate - The rate shall include the cost of all labour and materials specified above, including painting, cost of seam bolts and any extra G. I. hook bolts, nuts and washers, required.

8.3. SPECIFICATIONS for valley and flashing of plain galvanised steel sheets

8.3.1. Valley and flashing - Valley shall be 90 cm wide overall plain G.S. sheet 1.6 mm thick or other size as parallel in the item bent to shape and fixed.  They shall lap with the C.G.S. sheets not less than 25 cm which on other side.  The end laps of valley shall also be not less than 25 cm. Valley sheets shall be laid over 25 mm thick wooden boarding if so required.

Flashing shall be of plain G. S. sheet of 40 cm overall width 1.25 mm thick or 1.00 mm thick as specified in the item bend to shape and fixed.  They shall lap not less than 15 cm over the roofing sheets.  The end laps between flashing pieces shall not be less than 25 cm.

8.3.2. Laying and fixing - Flashing and valley sheets shall be fixed to the roof members below, such as purlins and valley rafters with the same 8 mm dia G. I. hook bolts and nuts and bitumen and G. I. limpet washers which fix the sheets to those roof members.

At least one of the fixing bolts shall pass through the end laps of the valley pieces on other side.  If this is not possible extra hook bolts shall be provided.  The free end of flashing shall be fixed at least 5 cm inside masonry with the mortar of mix 1:3 (1 cement: 3 coarse sand).

8.3.3. Surface of G. S. sheets under overlaps shall be painted with a coat of approved primer and two coats of approved paint suitable for painting G. S. sheets.

8.3.4. Finish - The edges of valley and flashing should be straight from end to end.  The surfaces should be true and without bulges and depressions.

8.3.5. Measurements - The length of the valleys and flashing shall be measured for the finished work correct to a cm.  The laps along the length of the valley or flashing pieces, including the portion embedded in masonry shall not be measured.

8.3.6. Rates - The rate for valleys, shall be for all the labour and materials specified above, including painting, cost of seam bolts and the cost of requisite G. I. hook bolts, nuts and washers required over and above those needed for connecting the roof sheets to the roof members.  The rate for valleys shall exclude the cost of boarding underneath which shall be paid for separately. The rate for flashing shall be for all the labour and materials specified above, and shall include the cost of painting and mortar for fixing in wall.

8.4. SPECIFICATIONS for gutters of plain galvanised steel sheets (fig.2)

8.4.1. Gutters - Gutter shall be fabricated from plain G. S. Sheets 1.25 mm thick or other size as specified in the item.

Eaves gutters shall be of the shape and section specified in the description of the item. The overall width of the sheet referred to therein shall mean the peripheral width of the gutter including the rounded edges, the longitudinal edges shall be turned back to the extent of 12 mm and beaten to form a rounded edge.  The ends of the sheets at junctions of pieces shall be hooked into each other and beaten flush to avoid leakage.

8.4.2. Slope - Gutter shall be laid with a minimum slope of 1 in 120.

8.4.3. Laying and fixing

Gutter shall be supported on and fixed to M. S. flat iron brackets bent to shape and fixed to the requisite slope.  The maximum spacing of brackets shall be 1.20 metres.

Where these brackets are to be fixed to the sides of rafters, they shall be of 40 x 3 mm section bend to shape and fixed rigidly to the sides of rafters with 3 Nos. 10 mm dia bolts, nuts and washers. The brackets shall overlap the rafter not less than 30 cm and the connecting bolts shall be at 12 cm centres.

Where the brackets are to be fixed to the purlins, the brackets shall consist of 50 x 3 mm M. S. flat iron bent to shape with one end turned at right angle and fixed to the purlin face with 2 Nos. of 10 mm dia bolts nuts and washers.  The bracket will be stiffened by provision of 50 x 3 mm.  M. S. flat whose over hung portion bent to right angle shape with its longer leg connected to the bracket with 2 Nos. 6 mm dia M. S. bolts, nuts and washers and its shorter leg fixed to face of purlin with 1 No.  10 mm dia, bolt, nut and washer.  The over hang of the vertical portion of the bracket from the face of the purlin shall not exceed 22.5 cm with this arrangement.  The spacing of the brackets shall not exceed 1.20 metres.The gutter shall be fixed to the brackets with 2 Nos. G. I. bolts and nuts 6 mm dia, each fitted with a pair of G. I. and bitumen washers.  The connecting bolts shall be above the water of the gutters.

For connection to down take pipes, a proper drop end or funnel shaped connecting piece shall be made out of G. S. sheet of the same thickness as the gutter and reverted to the gutter, the other end tailing into the socket of the rain-water pipe.  Wherever necessary stop ends, angles etc. should be provided.

8.4.4. Finish - The gutters when fixed shall be true to line and slope and shall be leak proof.

8.4.5. Measurements - Measurements shall be taken for the finished work along the centre line of the top width of the gutter connection to a cm.  The hooked lap portion in the junctions and gutter lengths shall not be measured.  The number of brackets which are fixed to purlins with stiffener flats should be measured.

8.4.6. Rate - The rate shall include the cost of all labour and materials specified above, including all specials such as angles, junctions, drop ends or funnel shaped connecting pieces, stop ends etc., flat iron brackets and bolts and nuts required for fixing the latter to the roof members.  Brackets of 50 x 3 mm flats fixed to purlins with flats will be paid extra.

8.5. SPECIFICATIONS for asbestos cement corrugated sheet roofing (fig. 3)

8.5.1. Asbestos cement corrugated sheets

The sheets shall be of the approved quality and shall conform to IS: 459.  The sheets shall be free from cracks, chipped edges or corners and other damages.

8.5.2. Slope - The roof shall not be pitched at flatter slope than 1 vertical to 5 horizontal.  The normal pitch adopted shall usually be 1 vertical to 3 horizontal.

8.5.3. Laying

The sheets shall be laid on the purlins and other roof members as indicated in the working drawings or as instructed by the engineer.

The maximum spacing of purlins under the sheets shall be 1.40 metres in the case of 6 mm thick sheets and these shall be in no case being exceeded.  Ridge purlins shall be fixed at 75 mm to 115 mm from the apex of the roof.

The top bearing surfaces of all purlins and of other roof members shall be in one plane so that the sheets when being fixed shall not require to be forced down to rest on the purlins.  The finished roof shall present a uniform slope and the line of corrugations shall be straight and true.  The sheets shall be laid with the smooth side upwards.

The sheets shall be laid with a side lap of half a corrugation and an end lap of 15 cm minimum in the case of roofs with a pitch flatter than 1 vertical to 2.5 horizontal (approx. 22 degree) or in the case of very exposed situations, the minimum permissible end lap shall be 20 cms. Side laps should be laid on the side facing away from the prevailing monsoon winds.

The free overhang of the sheets at the eaves shall not exceed 30 cm.  Corrugated sheets shall be laid from left to right starting at the eaves.  The first sheet shall be laid uncut but the remaining sheets in the bottom row shall have the top left hand corners cut or mitred.  The sheets in the second and other intermediate rows accept the first and the last sheets shall have both the top left hand corner and bottom right hand corner cut. The last or top row sheets shall all have the bottom right  hand corner  cut with the exception  of the last sheet which shall be laid uncut.  If for any reason such as on consideration of the direction of prevailing winds, laying is to be started from the bottom right hand corner, then the whole procedure should be reversed.

The ‘Mitre’ described above is necessary to provide a snug fit where four sheets meet at a lap. It is cut from a point 15 cm (or whatever the length of the end lap may be) up the vertical side of the sheet to a point 5 cm long along the horizontal edge.  This cutting may be done with an ordinary wood saw at site.

8.5.4. Fixing

Sheets shall be secured to the purlins and other roof members by means of 8 mm diameter galvanised iron J or L hook bolts and nuts.  While, J hooks are used for fixing to angle iron purlins, L hooks are used for fixing to R. S. joists, timber or precast concrete purlins.

The grip of the J or L hook bolt on the side of the purlin shall not be less than 25 mm.  Each galvanised iron J or L hook bolt shall have a bitumen washer and a galvanised iron washer placed over the sheet before the nut is screwed down from above. On each purlin there shall be one hook bolt on the crown adjacent to the side lap on either side.  Bitumen washer shall be of approved manufacture.  Galvanising of G. I. J or L hooks and washers shall be as provided.

Fig. 2 Galvanised Steel Sheet Gutter

The G. I. flat washer shall be of 25 mm in diameter. 1.6 mm thick and the bitumen washer shall be 35 mm in diameter and 1.5 mm thick.  The length of J bolt or crank bolt shall be as specified in Table 2 below.

Table 2

Sl. No

Situation

No. of Bolts &  Washers

Length of Bolts

1

At horizontal (end) laps of sheets. At eaves when filter pieces are used. At ridges when sheets and ridge pieces are secured by the same bolt.

Twice the No. of sheets on one horizontal course.

Depth of purlin plus 90 mm.

2

At eaves when filler pieces are not used. At ridge when corrugated sheets and ridge pieces are secured by the same bolt.

Twice the No. of sheets in the horizontal course.

Depth of purlin plus 75 mm.

3

At intermediate purlins where horizontal laps do not occur

Twice the No. of sheets in the horizontal course.

Depth of purlin plus 75 mm.

Fig. 3 A.C. Corrugated Sheet

Each nut shall be screwed lightly at first.  After a dozen or more sheets are laid, the nuts shall be tightened to ensure a leak proof joint.

Holes for hook bolts etc. shall be drilled and not punched always through the crown of the corrugation and not in valleys, in locations to suit the purlins while the sheets are on the roof in their correct position.  The diameter of holes shall be 2 mm more than the diameter of the fixing bolts.  No. hole shall be nearer than 40 mm to any edge of a sheet or any accessory.

Roof ladders or planks shall always be used when laying and fixing the sheets, to avoid damage to the sheets, and to provide security to the workmen.

8.5.5. Wind ties - Wind ties may be provided where the situation justify their provision.  These shall be of 40 x 6 mm flat iron section or of other size as specified.  These shall be fixed at the eave ends of the sheets.  The fixing shall be done with the same hook bolts which secure the sheets to the purlins.  Wind ties shall be paid for separately unless described as included in the items of the roof work.

8.5.6. Finish - The completed roof shall present a neat and uniform appearance and be leak proof.

Fig. 4 A.C. Corrugated Sheet

8.5.7. Measurements

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

8.5.7.2. The superficial area of roof coverings shall be measured on the flat without allowance for laps and corrugations.  Portions of roof covering overlapping of the ridge or hips etc. shall be included in the measurements of the roof.

8.5.7.3. Roof with curved sheets shall be measured and paid for separately.  Measurements shall be taken on the flat and not girthed.  The breadth of the roof shall be measured along the rest of the curved sheets.

8.5.7.4. No deductions in measurements shall be made for opening up to 0.4 sqm and nothing extra shall be allowed for forming such opening.  For any opening exceeding 0.4 sqm in area, deduction in measurements for the full opening shall be made and in such cases the labour involved in making these openings shall be paid for separately.  Cutting across corrugation shall be measured on the flat and not girthed.

8.5.8. Rate - The rate shall include the cost of all the materials and labour involved in all the operations described above except otherwise stated.  This includes the cost of roof sheets, galvanised iron J or L hook, bolts and nuts, bituminous and galvanised iron washers.

8.6. Specifications for asbestos cement semi-corrugated sheet roofing

8.6.1. Asbestos cement semi corrugated sheets - These shall be of the specified thickness and of approved quality and shall conform to IS: 459.

They shall be free from cracks, chipped edge corners or other damages.

8.6.2. Laying - The specifications for laying shall be the same as described except that (a) the sheets shall be laid with the end stamped ‘Top’  on the smooth side pointing towards the ridge, (b) the sheets shall invariably be laid from right to left starting at the eaves with the procedure for mitring etc. as described and reversed, (c) the side laps provided will be of one corrugation, the left hand small corrugation of each sheet being covered by the right hand large corrugation of the next sheet and (d)

Asbestos cement expansion joints shall be inserted every 45 metres or so in the length of the roof.  Specially manufactured expansion joint pieces shall be used for the purpose. The end lap of expansion joints shall not be less than 150 mm.  If the expansion joints may be between the purlins, these should be stitched with seam bolts.

8.6.3. Fixing - The specifications shall be same as described except that along each line of purlin there shall be a hook bolt in every vertical side lap corrugation and at the two verges and there shall be an additional hook –bolt through one of the two intermediate corrugations on each sheet.  When sheets are supported over intermediate purlins as in the case of length over 1.60 metres for 7 mm thick sheets and over 1.40 metres for 6 mm thick sheets, fixing accessories are required on the intermediate purlins, through each side lap and the verges only.

The number and length of bolts and number of bituminous felt and galvanised iron washers are given in Table 3.

Table 3

Sl.No

Situation

No. of bolts & washers

Length of bolts

1

At horizontal (end) laps of sheets. At eaves when filler pieces are used. At ridge when sheets and ridge pieces are secured by the same bolt.

Short bolts: The number of sheets in one horizontal course plus two long bolts. The number of sheets in one course less one           

Depth of purlin75 mm.

Depth of purlin plus

90 mm

2

At eaves when filler pieces are not used. At ridge when sheets and ridge pieces are not secured by the same bolt.

Twice the No. of sheets in one horizontal course plus one.

 

Depth of purlin75 mm.

3

At intermediate purlins when horizontal laps do not occur.

Twice the No. of sheets in one horizontal course plus one.

Depth of purlin75 mm.

8.6.4. Wind ties & finish - The specifications shall be as described.

8.6.5. Measurements - It shall be as described in addition, the end lap of the sheets under asbestos cement expansion joints where provided shall also be included in measurements.  Gap between the sheets under expansion joint shall not be measured.  The expansion joint sheets shall be measured for the finished work correct to one cm.

8.6.6. Rate - The rate shall include the cost of all the materials and labour involved in all the operations described above except otherwise stated.  This includes the cost of roof sheets, galvanised iron J or L hook bolts and nuts, bituminous and galvanised iron washers. The rate does not include cost of expansion joint sheet which shall be paid for separately.

8.7. Specifications for ridges and hips of asbestos cement (fig. 4).

8.7.1. Ridges and hips shall be of the same manufacture as the corrugated or semi corrugated sheets used for roof, unless specially permitted in writing by the engineer.  The sections shall be free from cracks, chipped edges or corners or other damages.

Ridges shall be of the type specified in the item, such as:

  1. One piece plain angular.
  2. Serrated or plain wing adjustable.
  3. Close fitting adjustable.
  4. North light adjustable and appropriate for the corrugated or semi-corrugated roof which is to be covered ‘Plain Wing Angular’ type ridges can be used only if the slope of the roof is exactly 30 degree.  Hips shall be of ‘under-rated adjustable for hips’ sections.
  5. Unserrated adjustable.

8.7.2. Laying - The ridge sections shall be laid as per manufacturers instructions with the rolls of the two wings in the case of adjustable ridges fitting closely and with the serrations of serrated ridges registering correctly with the sheets underneath.  The stagger lapping or two wings of an adjustable ridge section and the laps between adjacent pieces on the same wing of the ridges shall be as per manufacturers’ instructions. The end portions of the wings of the adjustable ridges which project beyond the verges of the roof shall be cut and trimmed off neatly.  Asbestos cement expansion joint ridge pieces shall be provided every 45 metres (approx.) of ridge where the latter is of the semi-corrugated serrated adjustable type. In laying hip pieces, serrations to suit the corrugations in the sheets below should be cut in them so that they will be a snug fit over the sheets.

8.7.3. Fixing

The wings of ridges shall be fixed to the sheets below with the seam bolts and nuts 8 mm diameter G. I. J or L hook bolts and nuts and bitumen and G. I. washers which fix the sheets to the purlins.  In additions, in north light adjustable ridges the curves of the two wings shall be joined together at their crown with 8 mm dia G. I. seam bolts and nuts, at the rate of 2 numbers per pair of wings.  Each seam bolt shall be provided with one bitumen and a pair of G. I. washers.

Where ‘Plain wing angular’ or ‘Plain wing adjustable’ ridges are used, the gaps formed by the roofing corrugations and the wings shall be filled with cement concrete 1:2:4 (1 cement: 2 coarse sand: 4 graded stone aggregate 12.5 mm nominal size) up to the full length of the overlap.  The exposed face shall be finished perpendicular to the sheeting.

Wing of hips shall be fixed to the roof members below with the same 8 mm dia G. I. J or L hook bolts and nuts which fix the sheet to those members.  In addition, they shall be secured to the sheets below with 8 mm dia G. I. seam bolts, nuts and washers, so that taken together with hook bolts there shall be bolt on each wing at least every fifth corrugation of the sheet below in the case of ‘Corrugation’ and at least every second corrugation of the sheet below in the case of ‘semi-corrugated’ sheets. The seam bolts shall each be provided with a pair of G. I. washers in addition to other accessories.

8.7.4. Measurements - The measurements for ridges and hips shall be taken for the finished work along the centre line of the ridge and hip lines in length, correct to a cm.  The laps in adjacent ridges or hip pieces shall not be measured.  The underlay of ridges under asbestos cement expansion joint pieces where the latter are provided shall however be measured.

8.7.5. Rate - The rate shall include the cost of all materials and labour specified above, but does not include (a) the cost of required G. I. hook bolts and nuts and their washers, (b) the cost of supplying and fixing asbestos cement expansion joint pieces, (c) the cost of closing the gaps between plain ridge and the sheet corrugations with concrete. Item (a) above will be covered by the rate for the asbestos cement sheet roofing while items (b) and (c) will be paid for separately unless specifically included in the description of the ridges or hip item.

8.8. Specifications for other roofing accessories of asbestos cement. 

8.8.1. Accessories - The other accessories that may be required to be used on a roof are (a) finishing pieces, eaves filler pieces, north light and ventilator curves, barge boards and expansion joint sheets (b) ridge finials, cowl type ventilators, curved boards for north light, curves, roof light expansion joints for ridge and expansion joint for north light curves and (c) ‘S’ type louver.  The accessories shall be of the type appropriate for use with corrugated or semi-corrugated sheets which form the roofing.

The accessories shall be of the same manufacture as the corrugated or semi-corrugated sheets used for the roof.  The pieces shall be free from cracks, chipped edges or corners and other damages.

8.8.2. Laying & fixing - These shall be laid and secured with the same G. I. hook bolts which secure sheets to the roof members below where possible or with separate G. I. hook bolts to the roof members below and / or with 8 mm dia G. I. seam bolts, nuts and washers to the sheeting, generally manufacturers printed instructions and as ordered by the engineer.  ‘S’ type louvers shall be fixed to ventilators to timber, M .S. angle or flat iron verticals spaced not more than 1.65 metre centres. The laps of adjacent pieces over the verticals shall not be less than 10 cm. The upper flat of the top most row of louvers shall be fixed to the vertical by 10 mm dia G. I. bolts and nuts and bitumen and G. I. washers.

Fig. 5 Asbestos Cement Accessories

The lower flats of the top and intermediate rows of louvers and the flat of the louvers pieces below shall be secured together to the verticals behind by 10 mm dia G. I. separating bolts threaded at both ends and of suitable length.  Each of these bolts shall be equipped with 2 pair of nuts, G. I. and bitumen washers.  The louver flats of the lowest line of louvers shall also be fixed to the verticals at the proper distance from the same by the use of similar separating bolts and nuts.

8.8.3. Measurements - The accessories listed under group (a) shall be measured for finished work in length correct to a cm.  Laps between adjacent pieces shall not be measured.

The accessories listed under group (b) shall be measured and paid for in number.  This applies in the case of final too where the unit shall consist of a pair of inter locking pieces.

The ‘S’ type louvers listed under group (c) shall be measured for the finished work in length of each row of louvers will not be taken into account in the measurements.

8.8.4. Rate

The rates for supplying and fixing, asbestos cement accessories listed in groups (a) & (b)  shall include  the cost of all materials and labour involved in all the operations described in A. C. roofing accessories, bolts, nuts, washers and other fixing accessories but does not include the members.

The rate for supplying and fixing roof lights shall not unless otherwise described in the item, include the glazing which shall be paid for separately.

The rate for supplying and fixing ‘S’ type louvers shall include all fixing accessories such as ordinary and separating G. I. Bolts nuts and bitumen washers including drilling the holes for the same in the vertical supporting member behind but shall not unless otherwise described in the item the cost of supplying and fixing the supporting members which shall be paid for separately.

8.9. Specifications for eaves and valley gutters of asbestos cement (fig. 6)

Nominal size

A

B

C

D

900 x 200 x 225

900

200

225

12.5

600 x 150 x 225

600

150

225

12.5

450 x 125 x 150

450

125

150

12.5

480 x 125 x 150

400

125

150

12.5

 

Nominal size

A

B

C

D

500 x 150 x 250

500

150

250

12.5

450 x 150 x 300

450

150

300

12.5

300 X 150 X 225

300

150

225

12.5

275 X 125 X 1/5

275

125

175

10.0

 

Nominal size

A

T

150

150

9.5

250

250

9.5

300

300

9.5

 

Type of gutter Nominal size A B C S K D

Half round

Gutter

150

150

90

240

70

105

110

90

100

250

200

200

300

100

105

110

115

90

100

150

300

200

200

300

100

105

110

115

90

100

150

OGEE gutter

125

150

90

240

70

105

110

90

100

200

150

90

240

70

105

110

115

90

100

150

Fig.6 Asbestos Cement Gutters

8.9.1. Gutters and accessories - Eaves gutters shall be of the type specified in the item such as (1) plain ended eaves, (2) boundary wall, (3) socketed eaves ogee and (4) socketed half round.  These shall be of standard size as stipulated in the item.  Valley gutters shall be of the ‘Plain’ ended valley types and of size as stipulated in the item.

These shall be approved manufacture, approved by the engineer.  The gutter sections and their accessories such as drop ends, stop ends, nozzles angles and union clips shall be free from cracks, chipped edges or corners and other damages.

8.9.2. Laying and fixing

Gutter shall be laid with a minimum slope of 1 in 120, which should be increased where possible.  Gutters shall be true to line and slope and shall be laid with the requisite accessories such as drop ends, stop ends, nozzles, angles and union clips as shown in the working drawing or as ordered by the engineer.

The size of outlet of drop ends and nozzles shall be of the same size as the size of the rainwater pipes into which they shall be discharging the water.

Gutters and their accessories shall be supported by M. S. flat iron bracket.  Where these brackets are to be fixed to the sides of rafters, they shall be of 40 x 3 mm section bent to shape and fixed rigidly to the sides of the rafter with 3 Nos. 10 mm diameter bolts, nuts and washers.  The brackets shall overlap the rafter not less than 30 cm and the connecting bolts shall be 11.5 cm centres.

Where the brackets are to be fixed to the purlins they shall consist of 50 x 3 mm M. S. flat iron bent to shape with one end turned at a right angle, and fixed to the purlin face with a 10 mm dia bolt, nut and washer.  The perpendicular over hang portion of 50 x 3 mm bracket shall be stiffened by another 50 x 3 mm flat, bent to right angle shape with its lower leg connected to the bracket with 2 Nos. 6 mm dia M .S. bolts, nuts and washers and its shorter led fixed to face of purlin with one number 10 mm dia bolt, nuts and washers.  The overhang of the vertical portion of the flat iron bracket from the face of the purlin shall not exceed by 22.5 cm with this arrangement.

The requisite slope in the gutters shall be given in the line of the bracket. The brackets shall be placed at not more than 90 cm centres.

The gutters shall be fixed to the brackets with 2 Nos. 8 mm dia G. I. seam bolts and nuts, each bolt and nut being equipped with a pair of bitumen and G. I. washers.  These connecting bolts shall be above the water line of the gutters.

Spigot and socket ends of gutters of ‘socketed eaves ornamental’ or ‘socketed half round’ type and their accessories shall be connected together at their laps with one row of 8 mm dia G. I. bolts and nuts, each bolt and nut being provided with a pair of bitumen and a pair of G. I. washers.  The gap between the socket and spigot shall be packed with approved plastic roofing compound, flanked on both sides of 6 mm dia asbestos rope.  The connecting G. I. bolts are then tightened so that the lapped joints become leak proof.  The outer faces of the packed asbestos rope shall not be farther than 6 mm from the edges of the spigot and socketed ends.

Where both ends of gutters and or their accessories to be connected together are of spigot ends they shall be laid as butt joints with 1.5 mm gap in between over union clips (loose socket pieces).  The union clip shall be connected to the two butt ends of the gutter or other section with two rows (one row per ends) of 8 mm dia G. I. bolts and nuts, each bolt and nut being provided, with a pair of bitumen and a pair of G. I. washers.  The gap between the union clips and the butt ends of the gutter sections or accessories shall be packed with approved plastic roofing compound flanked at both edges by 6 mm dia asbestos rope as before.  The whole joint shall be made leak proof by tightening the bolts.

The ends of ‘Plain’ ends eaves or boundary wall type and ‘plain’ ended valley type gutters and their accessories shall be laid for butt joints over union clips and connected together in the same manner as for connecting spigot and socket ends described in the proceeding sub-para.

The number of connecting bolts, nuts and washers and the quantities of 6 mm diameter asbestos rope and plastic roofing compound required per spigot socket of ‘ornamental’ and ‘half round’ gutters of different sizes and butt joints of plain ended ‘Boundary wall or eave’ and ‘valley’ type gutters of different sizes shall be shown in Table 4.

Table 4 Jointing materials per joint of gutter

Type of Gutter

Nominal size

6 mm dia Asbestos rope

Required per joint

Plastic roofing compound

8 mm dia nuts and bolts

G.I washer 25 mm dia

Bitumen washer 25 mm dia.

Socketed ornament

125 mm

0.57 m

170 g

1 No. 45 mm long

2 nos

2 nos

Socketed ornament

200 mm

0.98 m

255 g

3  No. 45 mm long

6 nos

6 nos

Socketed half round

150 mm

0.57 m

170 g

1 No. 45 mm long

2 nos

2 nos

Socketed half round

250 mm

0.92 m

567 g

3 No. 45 mm long

6 nos

6 nos

Socketed half round

300 mm

1.07 m

709 g

3 No. 45 mm long

6 nos

6 nos

Plain ended boundary wall or eaves

275x125

x 175 mm

0.97 m

737 g

8 No. 45 mm long

16 nos

16 nos

Plain ended boundary wall or eaves

300 x 150 x 225 mm

1.15 m

850 g

8 No. 45 mm long

16 nos

16 nos

Plain ended boundary wall or eaves

450 x 150 x 300 mm

1.38 m

1020 g

8 No. 45 mm long

16 nos

16 nos

Plain ended boundary wall or eaves

500 x 150 x 250 mm

1.43 m

1049 g

10 No. 45 mm long

20 nos

20 nos

Plain ended valley

400 x 125 x 250 mm

1.12 m

850 g

8 No. 45 mm long

16 nos

16 nos

8.9.3. Finish - The gutters and accessories when fixed shall be true to line and slope and shall be ridged.  All the joints shall be leaf proof.

8.9.4. Measurements - The measurement of gutters shall be taken for the finished work in length correct to a cm along the centre line of the gutters. The measured length of the finished gutters will include  the length of the finished gutters will include the length over accessories such as drop ends, stop ends, nozzles and angles, though the rate for the same shall not include the cost of the accessories unless specially described in the item.  Laps between the adjacent pieces of gutter and gutter section or between gutter section and accessories shall not be measured.

Accessories such as drop ends, stop ends, nozzles and angles shall be measured and paid for separately. Union clip (loose sockets) shall not be measured and paid for separately as they are included in the rate for gutters.

8.9.5. Rate - The rate for the gutters shall not, unless otherwise specified in the description item, include the cost of providing and fixing accessories such as drop ends, stop ends, nozzles and angles.  The rate shall include the cost of providing and fixing all union clips (loose sockets), all connecting G. I. bolts, nuts and bitumen and G. I. washers, M. S. flat iron brackets and their fixture to the gutter sections and to the roof members, asbestos rope and plastic roofing compound.

Extra over the rate for the gutter shall be paid for providing and fixing accessories, stop ends, drop ends angles and nozzles.  Where brackets of 50 x 3 mm size are provided in place of brackets of 40 x 3 mm size as indicated extra rate will be paid for separately.

8.10. specifications for painting of roof slab with hot bitumen

8.10.1. Preparing the surface - The surface shall be painted only when it is thoroughly dry.  The surface to be painted shall be cleaned with wire brushes and cotton or gunny cloth.  All loose materials and scales shall be removed and the surface shall be further cleaned with a piece of cloth lightly soaked in kerosene oil.

8.10.2. Painting with bitumen

The contractor shall bring the bitumen to site in its original packing and shall open and use it in the presence of the engineer or his authorised representative.  The containers shall not be removed from the site until the painting the job is completed and the engineer has satisfied himself regarding the quantity of bitumen actually used and has given his permission to remove the empty containers.

The surface prepared and treated shall be painted uniformly with bitumen of approved quality such as residual type of petroleum bitumen of penetration 80 /100, hot cut back bitumen or equivalent as per specifications of the manufacturer.  The coat of bitumen shall be continued 15 cm along the vertical surfaces joining the roof. In case of parapet walls it shall be continued up to the drip courses.

Residual type petroleum bitumen of penetration 80/100 shall be heated to a temperature of not less than 180 degree C and not more than 190 degree C and shall be applied on the roof surface at not less than 180 degree C.  Similarly, hot cut back bitumen shall be heated to a temperature of not less than 165 degree C and not more than 170 degree C and shall be applied on the surface at not less than 165 degree C.

Care shall be taken to see that no blank patches are left.  The quantity of bitumen to be applied per 10 square metres of roof surface shall be 17 kg, unless otherwise stipulated in the description of the item and shall be carefully regulated so that the application is uniform at the stipulated rate of 18 Kg. per 10 square metre.

8.10.3. Spreading sand - Immediately after painting, dry, clean sharp coarse sand at the rate of 60 cubic decimeter per 10 sqm shall be evenly spread and leveled over the surface when the bitumen is still hot.

8.10.4. Measurements - The superficial area of the surface painted shall be measured in square metres.  No deduction in measurements shall be made for unpainted areas of roof slab occupied by chimney stacks, roof lights, etc.  of areas, each up to 40 sq. decimetre. The measurements of length and breadth shall be taken correct to a cm.

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

8.11. SPECIFICATIONS FOR mud mortar terracing with the brick paving

8.11.1. Mud mortar - For mud mortar, selected soil which should be good quality earth suitable for brick making not containing excessive clay or sand, free from stones, kankar, vegetable maker and other foreign matter, shall be collected and stacked at site.  The soil shall not be collected from the locality infested with white ants.  Before laying on the roof, the soil shall be made damp by adding water about 12 hours earlier.  It shall be turned over so as to break clods and to pulverise the same.  Quantity of water to be added to the soil shall be carefully regulated so that the soil shall have optimum moisture content at the time of laying and compaction on the roof.  The soil shall be laid on the roof to requisite thickness and slope, well compacted with wooden rammers and thapies, to obtain an even surface to correct slope.  Average thickness of soil after compaction shall be as specified for the item.

Note: A practical way of determining the moisture content of soil suitable for giving good compaction is that the soil should contain that much quantity of moisture, which when a handful of soil is moulded with hand to the shape of a ball, it shall just retain its form.  If the soil on moulding cannot retain its shape of a ball, moisture content is inadequate.  On the other hand, if the ball can be plastically deformed on pressing with hand, the moisture content is on the high side.

8.11.2. Mud plaster - After laying the mud mortar, the surface shall be given a coat of mud plaster 25 mm thick and the plaster shall be allowed to dry and crack.

The mud plaster shall be prepared from the same soil as for mud mortar.  The dry soil shall be reduced to fine powder and mixed with water in a pit, adding fibrous reinforcing materials such as chopped straw (mortar) in proportion of 35 kg per cum of soil.  The mixture shall be allowed to mature for a period of not less than 7 days.  During this period it shall be worked over at intervals with feet and spades (phuwaras) so as to get pugged in to a homogeneous mass free from lumps and clods.  The mud mortar shall be puddled again very thoroughly just before use.

The consistency of mud mortar shall be checked by taking it a trowel and observing how it slides off the face of trowel.  The mortar shall readily slide off the trowel and should not be so wet to part on to large drops before falling.  Alternatively slump test may be performed in accordance with IS: 1199.  The slump should be about 70 mm.

8.11.3. Gobri leaping - After the mud plaster has dried, the surface should be given a coat of Gobri leaping so as to completely fill any crack that may have formed in the mud plaster.  Mortar for Gobri leaping shall be prepared by mixing equal quantities of fresh gobar and finely sieved clay and adding sufficient water to form a thin paste.  The quantity of gobar used in Gobri leaping shall not be less than 0.03 cum per 100 sqm of plaster area.  Five percent of cut back bitumen by mass of dry clay may be added to improve upon the water proofing quantities.

8.11.4. Laying of tile bricks - After the Gobri leaping has dried, flat tile bricks shall be laid using the minimum amount of plain mud mortar (without bhusa) as bedding so as to obtain correct slope and even surface of tile floors.  Care shall be exercised to see that mud mortar does not rise into the vertical joints of the tiles more than 12 mm.  The tiles shall be laid close to each other; the thickness of joints shall not be less than 6 mm and more than 12 mm in width.  After the tiles are well set and bedding mortar has dried, joints of the tiles shall be grouted with cement mortar of mix 1:3 (1 cement : 3 fine sand) such that all the joints of tiles are completely filled with mortar and the joints should be finished neat.  Cement used for the grouting mortar shall be mixed with 2% of integral water proofing compound which should conform to IS: 2645.

8.11.5. Curing - As soon as cement grouting obtains initial set, the surface of the tile brick floor shall be covered with wet gunny bags, hessian cloth or wet sand to prevent quick drying.  After 8-12 hours, the tile brick floor shall be cured by frequent sprinkling of water on the surface for a period of 7 days.  After curing has been done, the surface shall be swept clean.

The tile surface as completed shall be even and true to slopes of 1 in 48 or as specified and should be leak proof.

Note: When surplus earth of a suitable quality exists at the site of work, the contractor shall be allowed to use the same free of cost for laying the mud terracing, mud plaster and gobri leaping on the top.  The engineer shall be the final authority to decide whether the earth obtained from excavation is surplus to the requirements at site and is suitable for mud mortar work.

8.11.6. Measurements - Length and breadth shall be measured correct to a cm.  The measurements shall be taken for the finished work, (mud mortar a terracing stipulated thickness with mud plaster, gobri leaping and flat tile paving and grouting) over the tiled surface, in superficial area. No deductions in measurements shall be made for either openings or recesses for chimney stacks, roof lights or khurras, of area up to 0.40 sqm.  No extra shall be paid either for any extra materials or labour involved in forming such openings, recesses etc.  For areas exceeding 0.40 sqm deductions will be made in the measurements for the full opening but no extra shall be paid for any extra labour, materials etc. in forming such openings.

For plus or minus deviation from the average thickness stipulated for the mud mortar in the item, payments will be adjusted in the rate admissible to the contractor for the relevant schedule item provided that such deviations were authorised by the engineer in writing.

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

8.12. Specifications for paving over mumty roofs with tile bricks

The roofs shall be paved with tile bricks laid flat and grouted with cement mortar.

8.12.1. Tile Bricks - These shall conform to the specifications as detailed in 6.1.

8.12.2. Cement mortar - The cement mortar shall be of 1:3 mixes and of fine sand unless otherwise specified in the description of the item and shall conform to the specifications.

8.12.3. Preparing the surfaces - The surface shall be hacked, roughened and cleaned of all dust and other foreign matter.  It shall then be wetted before applying the mortar.

8.12.4. Paving and grouting - Cement mortar shall be spread in 12 mm layer over the surface evenly and to required slope.  Tile bricks which had been soaked as in brick work in water for at least an hour before hand shall then be laid open jointed and flat on the mortar and lightly pressed, and set to plane surface true to slopes etc. using a trowel and wooden straight edge.  The tile bricks shall be laid with their joints not more than 10 mm wide.  They shall be laid with their longitudinal lines of joints truly parallel and horizontal and at right angles to the sloping edges of the roof.

Transverse joints in alternate rows should come directly in line with one another.  Transverse joints in adjacent courses shall not break joints by less than 5 cm.  As soon as the paving is done, the open joints shall be grouted with cement mortar 1:3 (1 cement: 3 fine sand) cement used for grouting mortar shall be mixed with 2% (by unit of cement) water proofing compound conforming to IS: 2645. 

Care shall be taken to see that no joints are left unfilled or inadequately filled.  The joints shall be finished flush with the brick surface.

8.12.5. Curing - The tile paving shall be cured for at least 7 days during which period it shall be suitably protected from damage.

8.12.6. Measurements - Length and breadth shall be measured correct to a cm.  Measurements shall be taken for the finished work in superficial area covered.

No deduction in measurement shall be made for either openings or recesses for chimney stacks, roof lights, or for areas up to 0.40 sqm or any thing shall be paid for forming such openings. 

For similar areas exceeding 0.40 sqm deduction shall be made in measurements for all openings but nothing extra shall be paid for forming such openings.

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

8.13. specifications for lime concrete terracing

8.13.1. Materials - Brick aggregate shall not be more than 25 mm and also not less than 20 mm, nominal size and lime mortar shall be 1:2 (1 lime putty : 2 surkhi) unless otherwise specified in the description of the item.

The volume of wet mortar to be used will be 50% of stacked volume of brick aggregate, unless otherwise specified in the description of item.  The brick aggregate shall be kept moist thoroughly for a period of not less than 6 hours before use in the concrete mix.

The specifications for the materials and method of preparation of mortar and concrete shall conform in general to the specifications as described.

8.13.2. Laying

Lime concrete shall be laid (and thrown), in a single layer and spread and rammed with wooden rammers of weight not exceeding 2 kg to the specified average thickness, slopes and levels. The concrete shall be used when it is quite fresh, concrete left over from the previous days work shall in no circumstances, be used.

During this preliminary ramming, the surface shall be tested and kept perfectly true and even by means of a trowel, straight edge and spirit level.  The concrete shall then be further consolidated by two rows of labourers sitting close and beating the concrete in unison with wooden thappies (weight 1 to 2 kg) across the entire width of the roof and thus slowly traversing the length of the roof.  Special care shall be taken to consolidate the concrete properly at its junction with the parapet wall. This beating shall be continued for seven days or until the mortar is almost set and the wooden thappies rebound from the surface readily when struck on it.

While the beating is in progress the surface shall be liberally sprinkled with a mixture of Gur and boiled solution of bael fruit, in the proportion of 1.75 kg of Gur to 1 kg bael fruit boiled in 60 litres of water.

As soon as the beating is completed, the mortar that has come on top shall be softened by the addition of the solution of Gur and beal and smoothened with a float or trowel to a fine polish.  No plaster shall be used on any account for finishing the roof.

8.13.3. Curing - The concrete shall be kept wet after each day’s work and for such period of time as the engineer may direct but shall not be less than ten days.  The wetting shall be done by spreading straw and watering very frequently from a watering cane through a perforated rose, in moderate quantity, so as to ensure thorough wetting of the concrete.  Water shall not be poured on fresh concrete from large vessels as this may lead to damage to the finished surface.

8.13.4. Finish - The slope of the finished terrace shall not be less than 1 in 50 unless a flatter slope is expressly permitted by the engineer in writing.  The roof surfaces shall slope from all sides towards the outlets. The minimum thickness of the concrete at its junction with khurra shall be 5 cm.  The lime concrete shall overlap the cement concrete base of the khurra by 75 mm and shall be rounded to the edges of the khurra.  The lime concrete shall also be rounded at the junction of the roof slab and parapet.  The finished lime concrete shall present a smooth surface with correct slopes and uniform rounding wherever they occur.  The concrete should be leak proof and free from cracks.

8.13.5. Thickness - The average finished thickness of the laid concrete over the entire area shall conform to the average thickness specified in the description of the item.

The average thickness of concrete shall be measured correct to 5 mm. In the above measurement, the extra thickness at the rounding with the junctions of wall shall not be taken into account.

8.13.6. Measurements - Length and breadth shall be measured correct to a cm.  The area shall be calculated in square metres for the finished work in superficial area of the specified average thickness, up to two places of decimal.

No deduction in measurements shall be made for either openings or recesses for chimney stacks, roof lights etc. or for khurra for areas up to 0.40 sqm.  Nothing extra shall be paid either for any extra material  or labour  involved  in  forming such  openings or recesses, or in  rounding  the  concrete at junction of roof with parapet walls, chimney stacks, khurras etc. For similar areas exceeding 0.40 sqm deductions will be made in the measurements for the full openings but no extra shall be paid for any extra labour, material, etc. involved in forming such recesses and openings and in rounding at the junction aforesaid. Where average thickness of concrete laid exceeds the average thickness specified in the item, the extra depth shall not be paid for unless the same had been carried out under written orders of the engineer.

Where, however, such average thickness is found on measurements to fall short of the average thickness specified in the item the contractor’s rate will be reduced for the shortfall in thickness.

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

8.14. Specifications for lime concrete terracing with tile bricks paving

8.14.1. Lime concrete terracing - The specifications shall be same as described in 8.13.1 and 8.13.5 except that (a) the terrace concrete shall be finished rough and not with fine polish, (b) rounding the concrete at junctions with parapet walls, chimney stacks, raised sky lights etc. shall not be done as this will interfere with the tile paving to come on its top.

8.14.2. Tile bricks paving - The specifications shall be as described in 8.12.1 to 8.12.5.

8.14.3. These shall be the same as specified in 8.13.6.

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

8.15. Specifications for cement concrete gola (fig. 7)

8.15.1. Cement concrete - The specifications for concrete shall be the same as prescribed.

Fig. 7 Cement Concrete-Gola

8.15.2. Gola - A chase of 75 mm wide by 75 mm deep shall be cut in the parapet wall just above the junction of mud mortar plaster or lime concrete with parapet wall and it shall be filled with cement concrete 1:2:4 and external face finish with a slope of 1:0.75 and the exposed surface of the gola shall be plastered with cement mortar 1:3.

8.15.3. Expansion joint at every 3.5 to 4.5 metres shall be provided and filled with bitumen filler.  The bitumen filler shall be prepared by mixing bitumen, cement and coarse sand in the ratio of 80:1:0.25 (80 kg of hot bitumen: 1 kg of cement and 0.25 cum of coarse sand).

8.15.3. Curing - The finished surface shall be cured for at least 7 days.

8.15.4. Measurements - The length of the finished gola shall be measured at its junction with the wall face correct to a cm.  No deduction shall be made in measurements for gaps for water outlets.

8.15.5. Rate - The rate shall include the cost of all materials and labour involved in all the operations described above including the cost of bitumen filler in expansion joint.  The rate includes for all turnings and roundings at all the corners and risers.

8.16. Specifications for red or white sand stone roofing

8.16.1. Sand stone slabs - The stone slabs shall be hard, even, sound and durable.  They shall not absorb more than 5% of their dry weight of water after twenty four hours immersion.  Slabs shall have been sawn or chiseled in a plane parallel to the natural bed of the stone.  The slabs shall be rough chisel dressed on the top so that the dressed surface shall not be more than 6 mm from a straight edge placed on it.  The edges of the depressions or projections shall be chisel dressed in a slant, so that surface does not have sharp unevenness. The sides shall also be chisel dressed to a minimum depth of 20 mm so that the dressed edges at no place be more than 3 mm from a straight edge butted against it.  The thickness of the slab shall be uniform and as specified in the item with a permissible tolerance of 2 mm.  The slabs shall be uniform in length, the length being 5 to 8 mm less than the centre to centre spacing of the supporting wooden joists or RCC battens.  Unless the design required some other shape the slabs shall be rectangular. The width of the slabs may vary unless otherwise stipulated but shall not be less than 40 cm.

8.16.2. Rafter spacing - The maximum spacing of rafters (karries) or RCC battens supporting the slabs shall not exceed figures given in Table 5.

Thickness of slabs

Maximum spacing of rafters

40 mm

52.5 cm

45 mm

60 cm

50 mm

68 cm

The bearing of slabs over the karries shall not be less than 30 mm.  Where karri supports a slab from one side only, the bearing of such slab shall be for full width of the karri. For bearing over the wall, the stone slabs shall be bedded over a layer of cement mortar 1: 4 of thickness not less than 12 mm.

8.16.3. Laying - The slabs shall be washed clean and wetted before being laid.  The stone slabs shall be jointed in cement mortar 1:4.  The width of joints shall not be more than 8 mm not less than 5 mm.  The top joints shall be finished flush and ceiling joints pointed with the cement mortar 1:3.

8.16.4. Finish - The finished surface shall be true, level or slopped as shown in the plan or as directed by the engineer.  It shall be cleaned off all mortar droppings and cement markings both on top and on the under side.

8.16.5. Curing - The slabs and their joints shall be kept wet during progress of work for 7 days after completion.

8.16.6. Measurements - Length and width of finished stone slab work including bearing shall be measured correct to a cm.  The area shall be calculated in sqm correct to two places of decimal.

No deduction in area shall be made for openings in roof slab for chimney, stacks, roof lights etc. of area up to 40 square decimetre nor shall any extra be paid for extra labour, materials etc.  For openings exceeding 40 sq decimetre in area, deduction shall be made in measurements for the full opening but extra shall be paid for extra labour, material etc. in forming such openings.

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

8.17. SPECIFICATIONS FOR CLAY ROOFING, TILES, MANGALORE PATTERN CLAY TILE ROOFING

8.17.1. Classification - Roofing tiles, Mangalore pattern clay tile roofing, shall be of two classes namely, class AA and class A and shall be classified as per the characteristics as specified in Table 1.

Table 1 Classification of roofing tiles    (Clauses 3.1, 6.53, 6.54, 7.1 and 7.3)

Serial number and characteristic

Requirements

Class AA

Class A

1

Water absorption, percent max

19

24

2

Breaking load, kg. Min

102

82

a)

Average

102

82

b)

Individual

91

68

8.17.2. General quality - The roofing tiles shall be made from suitable clay of even texture and shall be well burnt.  They shall be free from irregularities, such as twists, bends, cracks and laminations.

The roofing shall be free from impurities like particles of stone, lime or other foreign materials visible to the naked eye either on the surface or on the fractured face of the tile obtained by breaking the tile.  However, occasional particles upto 2 mm in size may be permissible.  When struck, the tile shall give a characteristic ringing sound and when broken the fracture shall be clean and sharp at the edges. The class AA tile shall be uniform colour.

8.17.3. Shape - When the roofing tile is placed on either face on a plane surface, the gap at the comers shall be not more than 6 mm.

8.17.4. Lugs

8.17.4.1. Batten lugs – The tile shall have atleast 2 battern, lugs with base thickness (thickness at bottom) not less than 15 mm and thickness at top not less than 10 mm. The projection from surface of the tile shall be between 7 and 12 mm (See Fig.1).

8.17.4.2. Eave lugs – The tile shall be at least 2 eave lugs with base thickness not less than 15 mm and thickness at top not less than 10 mm. The projection from surface of lug shall be not less than 10 mm and shall be shaped to fit into the corrugations. (See Fig. 1).

8.17.4.5. Corrugations and cross ribs – The cross section of the roofing tile shall be such as to give the tile structural rigidity. This may be achieved by providing longitudinal corrugations with intermediate cross ribs or stiffeners. (See Fig.1).

8.17.4.6. Tie down hole – At least one hole shall be provided in one of the cross ribs near the eave end of the tile for securing the tile of the reeper or batten with wire.  The hole shall be clear and true and shall be not more than 2 mm in diameter, but shall be large enough to pass a 1.6 mm wire easily (See Fig. 1).

Dimensions and tolerances

8.17.5.1. Dimensions - There shall be three sizes of tiles with principal dimensions as given in Table- 2. The tolerance in length and width are given in 5.2.

Table 2 Dimensions of tiles

Sl No

Overall length

Overall width

1

410 mm

235 mm

2

410 mm

250 mm

3

425 mm

260 mm

Note: If the maximum overlaps are kept, the tile at Serial Number (1) is used for batten spacing upto 320 mm serial no. (2) Upto 350 mm and serial number (3) upto 360 mm. However, by reducing suitably overlaps in the tiles at serial Nos. (1) And (2) these can also be used for batten spacing upto 360 mm.

The minimum overlap (see Fig. 1) shall be 60 mm lengthwise and 25 mm width wise for each type of tiles.

8.17.5.2. Tolerances – For measurement of variations in length/width of tiles the difference between

  1. The overall length/width of three tiles (measured in accordance with 5.2.1) and
  2. The length/width of tile is calculated and this value shall be within the limits mentioned below:

For all sizes In mm

Value of length In mm

Value for width In mm

410 x 235

630 to 650

410 to 430

420 x 250

670 to 690

420 to 440

425 x 265

690 x 710

430 to 450

 Three tiles shall be selected at random from the sample selected under 6.3.  All bisters, loose particles of clay and small projections shall be removed.  These shall be arranged upon a level, surface interlocked along length/width wise on straight line in tight position and overall dimensions are measured (see Fig. 2).

8.17.5.3. Weight – The average weight of the six tiles, when dried at 105 to 110oC to constant weight and weighed, shall be not less than 2 kg and not more than 3 kg. The weight of tile shall be noted correct to the nearest 0.01 kg.

8.18. Specifications for water proofing with bitumen felts

8.18.1. Water proofing treatment with self finished felt shall be four courses or six courses as described in the item.  Four courses water proofing treatment with self finished felt is a normal duty treatment suitable for buildings where the cost of roof treatment is required to be restricted.

8.18.2. Six course water proofing treatment with self finished felt is a heavy duty treatment suitable for important structures.

8.18.2.1. Materials - Self finished felt (Annexure 8-A.2 and 8-A.3).  The self finished felt shall be of brand and manufacture conforming to the type and grade given in the description of the item.  This shall be one of the following types:

  1. Type 2 grade 1 is a glass fibre base bitumen felt conforming to IS: 7193.
  2. Type 2 grade 1 is a fibre (vegetable or animal) base felt conforming to in all respects to IS:1322-1993
  3. Type 2 grade 2 is a fibre (vegetable or animal) base felt conforming in all respects to IS:1322-1993
  4. Type 3 grade 1 is a hessian base felt conforming in all respects of IS: 1322.

8.18.2.2. Bonding materials - This shall consist of blown type petroleum bitumen conforming to IS: 702-1988 or residual petroleum bitumen conforming to IS: 73-1992 or mixture thereof.  The bonding material shall be so selected as to withstand the local condition of temperature and gradient satisfactorily. The penetration of bitumen used shall not exceed 40 in any case.  Suitable residual type petroleum bitumen is of penetration 30/40 (IS grade S-35).

Generally, blown type petroleum bitumen of S-90 shall be used for the base and intermediate layers of bonding material and for flashing,  while  residual type petroleum bitumen with higher penetration and low softening point shall be used for the finishing layer.  Suitable blown type petroleum bitumen is of IS grade 85 / 25 of approved quality.

Where proprietory brands of bonding materials are proposed to be used by the contractor they shall conform in all respects to the specifications in the preceeding paras.

1st course

3rd course

5th course

Kg/sqm

Kg/sqm

Kg/sqm

I

Four course treatment

1.45

1.45

-

II

Six course treatment

 

 

 

a

With type 3 grades 1 hessian base Self finished bitumen felt

1.45

1.20

1.45

b

With felts other than type 3 grade1 hessian base

1.45

1.20

1.70

8.18.2.3. Stone grit and pea-sized gravel - Stone grit shall be as specified and shall be 6 mm and down size.  Where pea-sized gravel is used it shall be hard, round and free from dust, dirt etc. The stone grit or pea-sized gravel shall not be spread over vertical and sloping faces of flashings and at drain mouths.  At these places the surface shall be painted with two coats of bituminous solution. The quantity of stone grit or pea-sized gravel required for the final course of four or six course treatment with Hessian base self finished bitumen, felt  type 3 grade 1 shall be 6 cubic decimetre.  For six course treatment with felt other than type 3 grade 1, the stone grit or pea sized gravel at 8 cubic decimetre per sqm shall be used.

Fig. 8 Water proofing

8.18.3. Preparation of surface

The surface to be treated shall have a minimum slope of 1 in 120.  This grading shall be carried out with lime concrete, cement concrete or cement plaster with coarse sand, as ordered, to the average thickness required and finished smooth.  Such grading shall be paid for separately.

Junctions between the rood and vertical faces of parapet walls, chimneys etc. shall be cased by running triangular fillets 7.5 x 7.5 cm size, in lime concrete or cement concrete.  At the drain mouths, the fillets shall be suitably cut back and rounded off for easy application of water proofing treatment and easy flow of water lime concrete where used shall conform to specifications as described except that the brick aggregate shall be 20 mm nominal size.  Cement concrete where used shall be 1:2:4 mixes (1 cement: 2 coarse sand: 4 graded stone aggregate 20 mm nominal size).  The provision of fillets shall be deemed to be covered by the item of water proofing and shall not be measured or paid for separately.

In existing roof where gola and drip course are provided at the junction of roof and vertical face of parapet wall, chimney stacks etc., these shall be dressed suitably and finished smooth so as to ensure an easy and gradual turning of the flashing. Any dismantlement or forming and finishing smooth the junction for forming the base of the flashing shall not be measured or paid for separately and shall be deemed to form part of the preparation of the surface in the water proofing treatment.

While the grading of roof surface is being done, it shall be ensured that the outlet drain pipe have been fixed and mouth at the entrance have been eased and rounded off properly for easy flow of water.

When any pipe passes through the roof to be treated, angular fillet of shape shown in Fig. 8 shall be built around it for the water proof treatment to be taken over it.  These fillets shall not be measured or paid for separately.

For carrying over and tucking in the water proofing felts into the parapet walls, chimney stacks etc. a horizontal groove 6.5 cm deep, 7.5 cm wide section with its lower edge at not less than 15 cm above the graded roof surface shall be left on the inner face of the same during construction if possible.  When such groove has not been left, the same shall be cut out neatly and the base at rear of the groove shall be finished smooth with cement plaster 1:4 (1 cement: 4 coarse sand).  Such cutting of the groove and its finishing smooth shall be deemed to be part of the water proofing item and shall not be measured or paid for separately.  No deduction shall be made either for not making the groove or when the later has already been left in the masonry by the construction agency.

Tucking in the water proofing where the parapet wall exceeds 45 cm in the height from the graded surface.  Where the height is 45 cm or less, no groove will be required as the water proofing treatment will be carried over the top of the parapet wall to its full thickness. In the case of low dividing walls of height 30 cm or less, outlets therein shall be cut open for full height and the bottom and sides shall be rendered smooth and corners rounded and such treatment shall not be measured and paid for separately.

Where expansion joints are left in the slab, the provision of dwarf walls and or RCC slabs for covering them and finishing the surface smooth shall be the responsibility of the construction agency, which had laid the roof slab and will not be included the operation of water proofing.

The graded surface of the roof and concrete fillets and the faces of walls shall be thoroughly cleaned with wire brushes and all loose scales etc. removed.  The surface shall then be dusted off.  Any crack in the roof shall be cut to “V” section, cleaned and filled up flush with cement mortar slurry 1:4 (1 cement : 4 coarse sand) or blown type petroleum bitumen of IS grade 85 / 25, or approved quality conforming to IS 702.  Such cleaning of the surface or treating the cracks shall not be paid for separately.

8.18.4. Priming coat - Where so specified, or required by the engineer for example under slightly damp conditions a priming coat consisting of a bitumen primer conforming to IS: 3384 applied with brush on the roof and wall surface at 0.24 litres per sqm to assist adhesion of the bonding material (i.e., bitumen).

Such application of primer shall be paid for separately, unless specifically included in the water proofing item.

8.18.5. Underlay - Where a floating treatment of water proofing with self finished bitumen felt is  required i.e. where water proofing treatment is required to be isolated from the roof structure, a layer of bitumen saturated felt (underlay) shall be spread over the roof surface and tucked into the flashing groove.  No bonding material shall be used below, the underlay in order to keep the underlay free of the structure.  The adjoining strips of the underlay shall overlap to a minimum of 7.5 cm at sides and 10 cm at ends.  The over laps shall be sealed with the same bonding material as used for the self finished felt treatment.  Unless specifically included in the water proofing item, the underlay treatment shall be paid for separately.

The underlay shall be of type 1 saturated felt conforming to IS : 1322 in all respects and having a total minimum weight of the finished bitumen felt in dry condition with mica dusting powder at 6.8 kg per 10 sqm.  The roll shall not be damaged or crack on being unrolled on a fairly smooth and flat surface.

8.18.6. Treatment

The water proofing shall consist of a four or six coarse treatment, as given in the description of the item, each layer of bonding materials, self finished bitumen felt or stone grit or pea sized gravel being counted as a course.

The choice of a four or six course treatment will depend on the climatic condition, the importance of the building, the durability required, cost and other relevant considerations.

A four course treatment shall consist of the following layers :

  1. Initial layer of bonding material applied hot at specified weight per unit area.
  2. 2nd layer of self finished bitumen felt of specified brand and manufacture conforming to the type and grade given in the description of the item.
  3. Third layer of bonding material.
  4. Final layer of stone grit of pea sized gravel spread at specified volume of material per unit area.

In a six course treatment, the first, second and third layer shall be of the same as in the four course treatment.  The fourth and fifth layer shall consist of self finished felt and bonding material respectively.  The sixth layer shall consist of stone grit or pea sized gravel.

The primer or under lay where required to be provided shall not count against the number of courses specified.

8.18.7. Laying - Bitumen bonding material of required grade shall be heated to the working temperature specified for the particular grade by the bitumen manufacturers and conveyed to the roof in buckets or pouring canes in weighed quantities.

Suitable working temperature for different grades of bitumen is as under:

(1). Blown type petroleum bitumen of IS grade 85/25 …180 degree C.

(2). Residual type petroleum bitumen of penetration 30/40 …180 degree to 190 degree C (IS grade S-35).

Drain outlets shall be given a four or six course treatment as specified for the roof in the description of the item in the manner specified for the flat roof surface.  Water proofing treatment shall be carried into the drain pipe or outlets by atleast 10 cm.  The water proofing treatment laid on the roof surface shall overlap the upper edge of the water proofing treatment in the drain outlets by at least 10 cm.

The self finished felt shall be cut to the required length, brushed clean of dusting material and laid out flat on the roof to eliminate curls and subsequent stretching. The felt shall normally be laid in length at right angles to the direction of the slope and laying shall be commenced at the lowest level and  worked  up to crest. The felt shall not be laid in single piece of very long lengths as they are likely to shrink 6 to 8 m are suitable lengths. The roof surface shall be cleaned and dry before the felt treatment is begun.  Each length of felt shall be laid in position and rolled up for a distance of half its length.  The hot bonding material shall be poured on the roof across the full width of the rolled felt as the later is steadily rolled out and pressed down. The pouring shall be so regulated that the correct weight of bonding material per unit area is spread uniformly over the surface.  Excess bonding material that gets squeezed out at the ends shall be leveled up as laying proceeds.  When the first half of the strip of felt has been bonded to the roof, the other half shall be rolled up and then unrolled on the hot bonding material in the same way.  Subsequent strips shall also be laid in the same manner.  Each strips shall over lap the proceeding one by atleast 7.5 cm at the longitudinal edges and 10 cm at the ends.  All overlaps shall be firmly bonded with hot bitumen.  Streaks and trailings of bitumen near edges of laps shall be leveled by heating the overlap with a blow lamps and leveling down unevenness. The third layer of bonding material in the four course treatment shall be carried out in a similar manner after the flashing has been completed.

In a six course treatment the third and fourth layers of bonding material and self finished felt shall be laid in the manner already described, taking care that laps in the felt are staggered from those in the second layer.  The fifth layer of bonding material shall be carried out after the flashing is done (See Fig. 8).

8.18.8. High parapet walls, chimney stacks etc. - Felts shall be laid as flashings wherever junctions of vertical and horizontal surfaces occur.  Longitudinal laps shall be 10 cm.  The lower layer of flashing felt in a six course treatment shall overlap the roof water proofing by not less than 20 cm while the upper layer shall overlap the roofing felt by 10 cm.  The minimum overlap of the flashing felt in four course specification over the roofing felt shall be 10 cm.

The flashing shall consist of the same four or six course treatment as for the roof except that the final course of stone grit or pea-sized gravel shall be replaced by an application of bituminous solution of approved quality in two coats on the vertical and sloping faces only, of the flashing. The overlap along the length of flashing shall stagger with nose in the second layer of flashing felt (in a six course treatment and with the joints in the roof felt).

The upper edge of the flashing felt shall be well tucked into the flashing groove in the parapet, chimney stacks etc. to a depth of not less than 6.5 cm.  Corresponding applications of bonding material shall also be made.  The flashing treatment shall be firmly held in place in the grooves with wood edges at intervals and the grooves shall filled up with cement mortar 1:4  or cement concrete 1:2:4 and surface finished smooth with the rest of the wall.  The cement work shall be cured for 7 days.  When dry, the exposed plaster joints of grooves shall be painted with bitumen and two coats of bituminous solution shall be applied on the vertical and sloping surface of flashing (see Fig. 8).

After top flashing felt layer has been fixed, the penultimate layer of bonding material shall be applied over the roofing felt and the horizontal overlaps and vertical and sloping surfaces of the flashings at the specified rate.  Stone grit or pea sized gravel shall then be spread uniformly over the hot bonding material on the horizontal roof surface at the specified quantity per unit area and pressed into it with a wooden roller.

8.18.9. Low parapet walls - Where parapet walls are of height 45 cm or less, bitumen felt flashings shall be provided in the same manner as for flashings in the case of high parapet walls except that the upper edge shall be carried up to the full height of the wall and taken right across the top of the parapet and down on the external vertical faces to a minimum distance of 5 cm (see Fig. 8)

8.18.10. Low dividing walls - Where low dividing walls or inverted beams are met with, the same shall be covered with a four or six layer treatment as for the main roof, the latter bearing carried down both sides of the wall and overlapping the roofing treatment as in the case of flashing of high parapet walls (see Fig. 8).

Drain outlets where formed in the low dividing walls, shall be given water proofing treatment of the same number of courses as specified for the flat roof surface.  The bottom and sides shall be so treated that all overlaps are in the direction of flow of drainage.

8.18.11. Expansion joints - Where the expansion joints are provided in the slabs, the joints and their cover slabs shall be suitably treated with water proofing. A typical sketch of an expansion joint with the RCC slabs on either side of the joint turned vertically up and covered with precast RCC cover slabs as given in Fig. 8. The cover slabs shall cover the vertical turned up dwarf walls by not less than 7.5 cm and are provided with throatings on their underside along their length.  The water proofing treatment shall be taken up the slopping junction fillets and the vertical faces on the walls to the underside of the cover slabs.  The cover slabs are given the water proofing treatment like the roof slabs, after the cross joints between adjacent cover slabs are first sealed with 15 cm width of roofing felt struck to them with bitumen.  The water proofing treatment shall be carried down the sides of the cover slabs to their full thickness.  Care shall be taken to see that overlaps if any in the roofing over the cover slabs stagger with the joints between cover slabs.

The formation of the expansion joints and provision of cover slabs shall be the responsibility of the construction agency.  The formation of the junction fillets and the water proofing treatment of the joint and cover slabs shall be carried out by the water proofing agency.  No extra shall be paid for the junction fillers or for the sealing of the cross joints in the cover slab with 15 cm width of bitumen strips.

8.18.12. Pipes - Where vertical pipe outlets are met with 7.5 x 7.5 cm fillets of lime or cement concrete of the type and section shown in Fig. 8 shall be provided and flashing of four or six course treatment, same as for the roofing treatment shall be laid.

The upper edge of the flashing shall be laid sloping down forward and butted against the pipe and annular depression so formed shall be filled with hot bitumen.  A circular metal collar in the shape of an inverted tuncated cone shall be fixed on the pipe to throw off the rain water clear of the flashing and this shall be paid for separately.

8.18.13. Terrace - Where roof surface are expected to be used precast cement concrete tiles or 40 mm thick cement concrete shall be laid on the water proofing treatment. In such cases, the final course or stone grit or pea sized gravel shall be laid in the water proofing treatment. Suitable adjustment in the rates will be effected for not providing the stone grit or pea sized gravel layer.  Cement concrete in situ flooring shall be laid in panel not exceeding 0.4 square metres each.  Precast tiles or in situ concrete flooring where laid shall be paid for separately unless included in the description of the water proofing item.

8.18.14. Measurements

Length and breadth shall be measured correct to a cm.  The area shall be calculated in square metres correct to two places of decimal.

Measurements shall be taken over the entire exposed area of roofing and flashing treatment including flashing over low parapet walls, low dividing walls and expansion joints and at pipe projections etc.  Overlaps and tucking into flashing grooves shall not be measured.

Vertical and sloping surfaces of water proofing treatment shall also be measured under the four or six course treatment as the case may be, irrespective of the fact that the final course of grit or pea sized gravel is replaced by bitumen primer.

Primer or saturated felt underlay, where provided, shall also be measured in the same manner as the water proofing treatment and paid for separately.  No deduction in measurements shall be made for either openings or recesses for chimney stacks, roof lights and the like, for areas up to 40 square decimetre (0.4 sqm) nor shall anything be paid for forming such openings.

For similar areas exceeding 40 sq. decimetre deductions will be made in measurements for full opening and nothing extra shall be paid for forming such openings.

8.18.15. Rate - The rate shall include the cost of all labour and materials involved in all the operations described above and the particular specifications given under the different items, with the corrections noted in the relevant sub-paras.

8.19. specifications for wooden ceiling

8.19.1. Boards - Boards shall be of the class of timber and of finished thickness as specified in the description of the item and shall be in accordance with the general specifications for wood work.  Only selected boards of uniform width shall be used. Unless otherwise specified in the description of the item or shown in the drawings, the width of boards selected for use shall not be less than 100 mm nor more than 150 mm.

The specific width of boards once selected within these two limits shall be maintained through out and shall not be varied except in the first  and last lines of boards adjustment of the two walls, where remaining odd width shall be adjacent equally on both sides.  The maximum length of the board in the finished work shall be 180 cm.  The minimum length of board in the finished work shall be

such that it will span at least two spacing of the supporting frame work except where shorter lengths are unavoidable, depending on the arrangements of the lines of heading joints which shall be carried out to the pattern ordered by the engineer. The boards shall be planed true on the exposed side.

Unless stipulated otherwise in the description of the item, the longitudinal joints of the boards shall be tongued and grooved, while the heading joints shall be of the square butt type and shall occur under the centre line of the supporting joint.  Heading joints in adjacent boards shall not be placeover the same joists, those in alternate boards being arranged in the same line, except where the joints are to be concealed by headings.

8.19.2. Frame - Timber frame of the class of wood and section specified in the description of the item for frame or as ordered by the engineer shall be provided.  The width of the frame scantling shall not be less than 50 mm.  The arrangements and spacing of the frame scantling shall be as per design furnished.  The frame shall be given two coats of approved preservative paint before the boarding is screwed. The frame and paints thereof the roof shall be paid for separately unless specifically included in the description of the item.  M. S. angles or other sections shall be used for suspending the frame and paid for separately. The bottom surface of the frame shall be checked and corrected or true plans and slopes.

8.19.3. Mild steel screws - Screws shall be got approved from the engineer before fixing.  They shall be of the slotted counter sunk head type of length not less than the thickness of the board plus 20 mm. The designation number shall not be less than 6 for screws of length 25 to 35 mm.

8.19.4. Fixing - The outer lines of boards shall be accurately fixed, parallel and close to the wall.  Each subsequent plank shall be carefully jointed up.  The boards shall be fixed to the frame scantling above with two screws at each of frame and one at every intermediate joist.  The screws shall be counter sunk and the screw holes filled with putty or sloping out wax.

The unexposed faces of planks shall be painted with wood preservative before fixing but this treatment will be paid for separately.

8.19.5. Finishing - The exposed side of the boards shall be truly level and plane. The joints shall be truly parallel and / or perpendicular to the walls. .Beadings shall then be fixed to the ceiling, to the size and pattern required. These shall be measured and paid for separately unless specifically included in the description of the ceiling item.

8.19.6. Measurements - Length and breadth shall be measured correct to a cm.  Areas shall be worked out to nearest 0.01 sqm.  The ceiling shall be measured in square metres of superficial area of the finished work. No deduction in measurements shall be made for openings of areas up to 40 square decimetre.  Nothing extra shall be payable either for any extra material or labour involved in forming such openings.  For openings exceeding 0.40 sqm in area, deductions in measurements for the full opening will be made and in such case any labour involved in making these openings shall be paid for separately in running metres. Boarding fixed to curve surfaces in narrow widths shall be measured and paid for separately and shall be included making the joints to proper splay. Circular cutting and waste shall be measured and paid for separately in running metres.

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

8.20. specifications for ceiling with insulating building boards

8.20.1. Insulating building boards - The insulating building boards shall be of approved quality as per IS: 3348 and, unless otherwise specified, shall have square edges.  The dimensions shall be subjected to the tolerances given in the Table 6 below:

Table 6 Dimensions and tolerances

Sl No

Type of

Nominal thickness

Tolerance on  thickness

Length

Width

Tolerance on length and width

1

Fibre insulation board, Ordinary or flame retardant type

9

±0.75

365,300

180,150

120 cm and below  ± 3 mm

 

 

12

±0.75

270,240

120,100

 

 

18

±1.00

210,180

90,60

Above120 cm ± 6 mm

 

 

25

±1.25

150,120

45 and 30

 

 

 

 

100,90

 

 

 

 

 

60,45

 

 

 

 

 

and 30

 

8.20.2. Frame - Timber frame of the class of wood and section specified in the description of the relevant item for the frame or as ordered by the engineer shall be provided.  The width of the scantlings provided shall be sufficient to provide a minimum nailing surface of 50 mm. The longitudinal and header scantlings shall be so arranged that (a) the boards can be fixed to form the panel arrangements required as per drawings or as ordered by the engineer (b) the longitudinal scantling to which the boards are mainly fixed are spaced at 30 to 45 cm centres, the actual spacing selected depending on the width of the cut board in the panel arrangement, (c) all edges of the cut board units are supported either on the longitudinal scantlings or on the header scantlings.

The frame shall be given two coats of approved preservative paint (to be paid for separately) before the board is nailed on M.S. angles or other sections shall be used for suspending the frame and will be paid for separately. Where the joints in the board are to be covered with beadings the framing centres should be 3 to 6 mm to allow for space between boards.

The framing and painting thereof shall be paid for separately unless specifically included in the description of the ceiling item.

The bottom surface of the frame shall be checked and corrected to true planes and slopes.

8.20.3. Nails - The sheets shall be fixed to the frame scantling with G. I. headless nails 2,.24 mm dia when the joints are to be left exposed.  Where the joints will be covered with beadings, the sheets are to be fixed to the frames scantlings with G. I. felt headed (clout) nails 2.5 mm dia.  The length  of the nails shall generally be equal to thickness of sheet plus 25 mm so that their grip on the framing members will not be less than 25 mm.

8.20.4. Fixing - The boards shall be applied with lengths parallel to all joints centered over the framing members. Where joints are to be covered, the boards may be spaced 3 to 6 mm apart as described in the respective manufacturers’ specifications. Where joints are to be left exposed the sheets shall be butt laid with their edges abutting in moderate contact, but without having to force them into place. The boards shall be supported and held tight to the grounds with timber pieces the later being moved outwards as the nailing proceeds. The boards are first nailed to the intermediate framing member proceeding from the centre of the board outwards, the edges being nailed last.

Where the joints are to be left exposed, the outer rows of nails are placed at 10 cm centres and about 12 mm from the edge of the sheet.  In the rows in the middle of the sheets, the nails are placed 20 cm apart. The nails should be counter sunk in the under side of board with a suitable punch. Care shall be taken in driving the nails so that the sheets are not marked by hammer blows. Where the joints are to be covered with beadings, felt headed (clout) nails shall be used instead of lost head nails. The spacing of the nails in the interior rows in boards shall be the same as in the preceding para. In the outer rows at edges to be covered by beadings, the nails will be spaced at 20 cm centres in each row but with the naisl staggered. The beadings will then be fixed over the sheets with screws at 20 cm centres in each row with the screws in the two rows staggered and passing through beading, sheet and framing so that ultimately the spacing of the fixing (nails and screws taken together) in each row will be at 10 cm centres so far as the sheets and frames are concerned.

8.20.5. Finishing - The exposed side of the board shall be truly level and plane without any local bulges or sags. The joints shall be truly parallel and / or perpendicular to the walls. The width of joints shall be uniformed. Care shall be taken to see that the uniformity of colour of the sheets is not spoilt during the fixing operations. Where the joints are required to be covered, beadings of side, pattern and material as ordered shall then be fixed with screws. These shall, however, be measured and paid for separately, unless specifically included in the description of the ceiling item.

The ceiling shall be treated with distemper or painting if so required but such surface treatment will be paid for separately, unless specifically included in the description of the ceiling item.

8.20.6. Measurements and rate - These shall be the same as described 8.18.6 and 8.18.7.

8.21. specifications for hard board / particle board / a. C. Sheet ceiling

8.21.1. Boards

8.21.1.1. Particle board - The specifications for particle board shall be same as per Section 7.2.3.

8.21.1.2. Hard boards - The specification for hard boards shall be same as per Section 7

8.21.1.3. A.C. Sheets - The specifications for A. C. sheets shall be same as per Section 7

8.21.2. Frame - The specifications as described shall apply except that the maximum spacing of the longitudinal scantlings shall be 40 cm centres. In case of hard board the sheets shall be damped with water on the textured face before they are fixed.  This shall be carried out by brushing the textured face evenly and liberally with a sponge or swab soaked in water.  After this, the sheets are stacked with the damped sides against each other, in pairs and left to remain for a period of 24 or 48 hours as recommended by the respective manufacturers.  During this conditioning the sheets should be sheltered from the sun and strong heat.

The specifications for cutting and chamfering etc. will be same as in 8.19.2.

Nails - The specifications shall be the same as in 8.19.3

Fixing - The specifications as specified shall apply as in 8.19.4

Finishing - The specifications as specified in 8.15.5 shall apply with the exception that normally no surface treatment like painting, varnishing, etc. is necessary.

Measurements and rate - These shall be the same as specified in 18.6 and 18.7.

8.22. Specifications for plaster of paris (gypsum anhydrous) ceiling over wooden strips

8.22.1. Frame - The frame work shall be of the specified wood wrought and framed.  In case of slopping roofs wooden battens of suitable section (depending upon the span and load to be carried) shall be firmly fixed as main supports, to the under side of the tie beams and nuts of proper size. In case of flat roofs, the 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 M. S. bars of suitable sections and encroached therein.  Cross battens of 50 x 40 mm sections at 40 cm centres or so, shall then be fixed at right angles to the main battens.  The frame work shall be treated with approved wooden preservative before it is covered with ceiling.  The underside of the frame work shall be true to planes and slopes. The frame work for ceiling shall be paid for separately unless specifically included in the description of the ceiling item.

8.22.2. Wooden strips - Wooden strips 25 x 6 mm of first class kailwood, (unless otherwise stipulates specifically in the description of the item) shall be fixed to the cross battens, in the parallel rows with gaps of 10 mm in between adjacent rows, by means of felt headed (clout) nails.  The strips shall be fixed butt jointed and not overlapped.  The joints shall be staggered.  The minimum length of strips of be used shall be 1.5 m depending upon the length of strips required.

8.22.3. Rabbit wire mesh - Rabbit Wire Mesh shall then be fixed to the underside of wooden strips and their junctions with the battens with nails at pitch of 15 to 20 cm as ordered by the engineer. The rabbit wire mesh shall be straight, tight and perfectly true to planes and slopes and without any sagging and shall be slightly below the underside of the laths to allow the plaster to encase the metal round.

8.22.4. Plaster of Paris - The Plaster of Paris shall be of the calcium-sulphate semi-hydrate variety.

Its fineness shall be such that when sieve through a sieve of IS sieve designation 3.35 mm for 5 minutes after drying the residue left on it shall be not more than 1% by weight.  It shall not be too quick setting.  Initial setting time shall not be less than 13 minutes.  The average compressive strength of material determined by testing 5 cm cubes after removal from moulds, after 24 hours and drying in an oven at 40 degree C till weight of the cubes is constant, shall not be less than 84 kg per square metre.

8.22.5. Applications - The material will be mixed with water to a workable consistency.  Plaster of Paris shall be applied to the underside of the laths over the rabbit wire mesh in suitable sized panels and finished to a smooth surface by steel trowels.  The plaster shall be applied in such a manner that it fully fills the gaps between the laths and the thickness over the laths is as specified in the description of the item.  The joints shall be finished flush to make the ceiling in one piece.  The finished surface shall be smooth and true to plane, slopes or curves as required.

8.22.6. Measurements - Length and breadths of superficial area of the finished work shall be measured correct to a cm.  Area shall be calculated in square metre correct to two places of decimal.  No deduction will be made of openings of areas up to 40 square decimetre not shall extra payment be made either for any extra material or labour involved in forming such openings.

For openings exceeding 40 square decimetre in area, deduction in measurements shall be made but extra will be payable for any extra material or labour involved in making such openings.

Curved surfaces shall be measured and paid for separately from flat surfaces.  The work shall be deemed to comprise of flat surfaces only unless specifically stated otherwise in the description of the item. Any sunk or raised moulding in the plaster shall be measured and paid for separately, deductions being made from plastering on ceiling only if the width exceeds 15 cm.  Ceiling at a height greater than 5 metres shall be so described and measured separately stating the height.

8.22.7. Rate - The rate shall include the cost of all materials and labour involved in all the operations described above including all scaffolding, staging etc. The frame work as mentioned supporting the ceiling will be paid for separately unless otherwise stipulated in the description of the item.

The rate does not include for any raised or sunk moulding or for any patterned finishing of the surface which will be measured and paid for extra over the plaster work.

8.23. specifications for plaster of paris (gypsum anhydrous) tiles ceiling

8.23.1. Frame - Timber frame of the class of wood and section as specified in the description of relevant item for the frame or as ordered by the engineer shall be provided.  The width of the scantlings provided shall be sufficient to provide a minimum nailing surface of 6 cm.  The longitudinal and header scantlings shall be so arranged that the tiles can be fixed to form the panel arrangement required as per drawings, or as ordered by the engineer and there is supporting scantling under each and every edge of the tiles.

The framing shall be paid for separately unless specifically included in the description of the item.

8.23.2. Plaster of Paris shall be as specified in 8.22.4.

8.23.3. Preparation of tiles - Tiles of plaster of Paris reinforced with hessian cloth shall be prepared in suitable sizes as shown in drawings or as ordered by the engineer.  The maximum sizes of tiles shall be limited to 75 cm in each direction.  Wooden forms of height equal to the thickness of tiles shall be placed on a truly level and smooth surface such as a glass sheet.

The section of form sides shall be such that the edges of the tiles shall be provided with a neatly formed chamfer alround of 5 mm width and 8 mm depth, unless the tiles are to be provided with cover fillets over joints in which case the edges of the tiles shall be truly spare.  The glass sheet or surface on which form is kept and the form sides shall be given a thin coat of non-staining oil to facilitate the easy removal of the tiles.  Plaster of Paris shall be evenly spread into the form up to about half the depth and hessian cloth weighing not less than 230 gms per square metre shall be pressed over the Plaster of Paris layer. The ends of the hessian cloth shall be turned over all the edges to form a double layer to a width of 5 cm. The hessian cloth shall be of an open webbed texture so as to allow the plaster below and above to intermix with each other and form an integral whole. The form shall then be filled with plaster of Paris which shall be uniformly pressed and then wire cut to an even and smooth surface. The tile so moulded shall be allowed to set initially for an hour or so and then removed from the form and allowed to dry and harden for about a week, good tile after drying and hardening shall give a ringing sound when struck. The tiles shall be true to shape and size and with clean and regular chamfers. The exposed face shall be truly plane and smooth.

8.23.4. Fixing - The tiles so prepared shall be fixed to the cross battens of the ceiling frame with 40 mm brass screws at spacing not exceeding 20 cm centre to centre on all edges. The tiles shall be laid with their edges in just close position to the adjoining tiles without any gap in between. The line of screws shall be not less than 15 mm away from the edge of the tiles. The screws shall be slightly shall be drilled. The counter sunk heads of screws shall be covered up with Plaster of Paris and smooth finished. When a surface unbroken by visible joints is required, then the joints shall be filled with Plaster of Paris and trowelled smooth so that the whole surface appears as one without any joint. Nothing extra shall be paid for this closing of joints.

8.23.5. Measurements - These shall be the same as specified. All special sizes and shapes of tiles necessitated by the openings referred to in the above para shall have to be made without any extra cost. The work at a height greater than 5 metres shall be paid for separately.

8.23.6. Rate - The rate shall include the cost of all materials, labour, form work, scaffolding etc. involved in all the operations described above.  The rate does not include for covering the joints with beading, unless specifically stipulated in the item.  The rate applies for plain faced tiles only and does not include tiles with sunk or moulded face.

8.24. specifications for wooden cover fillets beading for ceiling

8.24.1. Beading - The beadings shall be of the specified wood and of size as given in the description of the item. Unless otherwise described the beading shall be of the plain variety with square edges.

The arrangement of the beading shall be as per drawings or as ordered by the engineer and shall be fixed normal over the joints to be covered.

8.24.2. Fixing - The beading shall be planed smooth overall exposed faces and true on the rear face fixed centrally over the butt joints between the two boards with iron wood screws in two rows on either side of the joint. The spacing of screws thus shall pass through the beading, ceiling board and then into the ceiling rafters with a minimum grip of 25 mm in the latter and where the beading is to be fixed to the board above for ornamental purpose there being no frame work scantling above, then the beading shall be fixed with screws which will be driven through the full depth of the board and their spacing shall be same as before. The screws to be fixed shall be got approved by the engineer before fixing. These shall be oiled before insertion and shall be screwed in by means of a screw driver and in no case the use of hammer for fixing the screws is permissible. The screws shall be driven slightly counter sunk below the surface of the beading.

8.24.3. Finishing - The beading shall be finished smooth and fixed in such a workmen like manner that there is absolutely no gap left between the beading and the ceiling board nor in the joint faces.  The beading line shall be absolutely straight and parallel and the plane of the under side of the beading shall be uniform.

The junction of the beading shall be of fully mitred or of partly mitred kind as shown in the drawings or as ordered by the engineer.  Where joints are to be fully mitred both the longitudinal as well as the cross beading shall be to the exact length as required by the panel arrangement.  Where the joints are to be partly mitred variety and the length of the beading in one direction can run continuously over more than one panel than the minimum lengths of these beadings  shall be 1.8 metre and the joints shall come at a corner of a panel and not in the middle of the panel side.

8.24.4. Measurements - Beading shall be measured in length in running metres correct to a cm.

8.24.5. Rate - The rate shall include the cost of all materials, labour and scaffolding involved in all the operations, and shall apply to square edges beading unless otherwise stipulated in the description of the item.  Chamfering edges, if payable, will be separately measured and paid as extra per running metre of beading.

8.25. specifications for rain water spouts

The sectional area of rain water spouts provided shall be generally at the rate of 1 square cm per 70 to 80 square decimetre of roof area drained.  However in locations subject to excessive and high intensities of rainfalls, the area of spouts provided may be suitably increased to suit local conditions.  No spout shall be less than 80 mm diameter.  The spacing of spouts shall be arranged to suit the position of openings in the wall.

8.25.1. Stone ware spouts - The spouts shall be 100 mm in diameters and 60 cm long. The stone ware pipe shall be perfectly sound, free from fire cracks, imperfections of glazing etc. They must be straight cylindrical and of standard nominal diameter and length and depth of socket.  Full length of pipes shall be used on the work.  They must be thoroughly salt glazed inside and outside shall generally conform to IS: 651.

8.25.2. Fixing - These shall be provided at the months of khurras and shall be fixed in cement mortar 1:3 with the socket embedded in the masonry and the spigot end projecting outside.  The masonry alround the pipe and socket shall be thoroughly wetted and the holes shall be given a coat of cement mortar alround.  The S. W. pipe shall then be inserted and fixed with a surround of mortar.  In case the hole is made much larger than the size of the pipe, cement concrete 1:2:4 shall be used to fill in the annular space.  The spouts shall slope the wall shall be uniform and not less than 40 cm.  The entrance into the pipe shall be smoothly rounded to meet the internal bore of the pipe to facilitate easy flow. Care shall be taken to ensure that the vertical plane through the centre line of the spouts is at right angles to the plane of the wall.  Spouts in a row shall be true to line.

8.25.3. Measurements - Spouts shall be measured in numbers.

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

8.25.5. Cement concrete spouts - These shall be 100 mm in diameter and 60 cm long.

All pipes shall be new and perfectly sound free from cracks, cylindrical, straight and of standard nominal diameter, length and depth of socket.  They shall conform to IS: 458.  They shall be of un-reinforced cement concrete manufactured by pressure process and shall have been texture.  The length of the pipe shall be the length of barrel exclusive of the internal depth of the socket.

8.25.6. Fixing, measurements and rate - Shall be as specified.

8.26. specifcations for cast iron rain water pipes

8.26.1. Cast iron pipes - Pipes shall conform to IS: 1230-1979 and shall be true, smooth and cylindrical, their inner and outer surfaces being as nearly as practicable concentric.  These shall be sound and uniform castings, free from laps, pin holes or other imperfections and shall be neatly finished and carefully fitted both inside and outside.  The ends of pipes shall be reasonably square to their axes.

8.26.2. Dimensions - C.I. rain water pipes shall be of the dia specified in the description of the item and shall be in full length of 1.8 metre including socket ends of the pipes, unless shorter lengths are required at junctions with fittings.  The pipe lengths shall be in each case be with socket. The pipes shall be supplied without ears unless otherwise specifically mentioned.

The pipes supplied shall be factory painted (with a tar base composition) both inside and outside which shall be smooth and tenacious.

Every pipe shall ring clearly when struck all over with a light hand hammer.  When shorter pipes are cut from full lengths they shall be cut with a hacksaw.  The sizes, weights, sockets and tolerances of pipes shall be as shown in Table 7.

Table 7 Dimensions and weight of C.I Rain water pipes

Nominal size of pipes (internal diameter in mm)

50

75

100

125

150

 1. Pipe

 

a

External diameter in mm

53

79

104

130

156

 

Tolerance in mm

± 3

± 3

± 3.50

± 3.50

± 4.00

b

Thickness in mm

3.00

3.00

3.00

3.00

4.00

 

Tolerance in mm

± 1

± 1

± 1

± 1

± 1

c

Nominal weight of 1800 mm long pipe

 

 

 

 

 

 

Without ears in kg

7.50

11.00

14.00

20.00

25.00

 

Tolerance in weight

(-)10%

(-)10%

(-)10%

(-)10%

(-)10%

 

Tolerance in length in mm

±13.00

±13.00

±13.00

±13.00

±13.00

 2. Socket

a

Internal diameter in mm

63

89

114

139

167

 

Tolerance

±3.00

±3.00

±3.00

±3.00

±3.00

b

Thickness in mm

4.00

4.00

4.00

4.00

4.00

 

Tolerance in mm

±1.00

±1.00

±1.00

±1.00

±1.00

c

Internal depth in mm

60

65

65

75

75

 

Tolerance in mm

± 10

± 10

± 10

± 10

± 10

Note: (1) All dimensions are in mm. (2) Pipes weighing more than the nominal weight may be accepted provided they comply in every  other respect with the requirements of this standard.

(3) The above table applies only to rain water pipes fixed on wall face.

(4) For pipes and fittings which are to be embedded in masonry, specifications shall correspond with those of pipes for soil, waste, and vent pipes.  For their weights, specifications under chapter 19 shall be referred to.

8.26.3. Fixing and jointing - Pipes shall be either fixed on face of wall or embedded in masonry, as required in the description of the item. Plain pipes (without ears) shall be secured to the walls at all joints with M. S. holder bat clamps.  The clamps shall be made from 1.6 mm thick galvanised M. S. sheet of 30 mm width, bent to the required shape and size so as to fit tightly on the socket of the pipe, when tightened with screw bolts. It shall be formed out of two semi-circular pieces, hinged with 6 mm dia M. S. bolt on one side and provided with flanged ends on the other side with hole to fit in a screw bolt and nut, 40 mm long.  The clamp shall be provided with a hook made out of 27.5 cm long 10 mm diameter M. S. bar, riveted to the ring at the centre of one semi circular piece.  The details of the clamps are shown in Fig 9. The clamps shall be fixed to the wall by embedding their hooks in cement concrete block 10x10x10 cm in 1:2:4 mix for which necessary holes shall be made in the wall at proper places. The clamps shall be kept about 25 mm clear off finished of wall, so as to facilitate cleaning and painting of pipes (Fig. 9).

Note - Where G. I. steel clamps are not provided, M. S. sheet clamps of 3 mm thick and 20 mm wide shall be used for making the clamps.

The pipes shall be fixed perfectly vertical or to the lines as directed. The spigot of the upper pipe shall be properly fitted in the socket of the lower pipe such that there is a uniform annular space for filling with the jointing material.  The annular space between the socket and the spigot shall be filled with a few turns of spun yarn soaked in neat cement slurry. These shall be pressed home by means of caulking tool.  More skins of yarn shall be wrapped if necessary and shall be rammed home.  The joint shall then be filled with stiff cement mortar 1:2 (1 cement: 2 fine sand) well pressed with caulking tool and finished smooth at top at an angle of 45 degree sloping up.  The joints shall be kept wet for not less than 7 days by typing a piece of gunny bag, four fold, to the pipe and keeping it moist constantly.

Where pipes are to be embedded in masonry, these shall be fixed in masonry work as it proceeds.  In such cases care shall be taken to keep the pipes absolutely or to the line as directed by the engineer.  The pipe shall have a surrounding of 12 mm minimum thickness of mortar at every portion of the external surface. The mortar shall be of the same mix as is used in the masonry.  The joint shall be caulked with lead as soon as the next length of pipe is placed in position.  The open end (socket end) of the pipe shall be kept closed till the next length is fitted and jointed, to prevent any brick bats or concrete or pieces of wood falling in and choking the pipe. The depth of lead from the lip of socket shall be 25 mm minimum.  In case of 100 mm dia, 75 mm and 50 mm pipes, the quantity of lead required per joint shall be 1.00 kg, 0.66 kg and 0.50 kg respectively for purpose of reckoning theoretical quantity of lead due to dimensional tolerances allowed as per Indian Standards.  This variation includes allowances of wastage also.

The spigot end shall butt the shoulder of the socket and leave no gap in between.  The annular space between the socket and the spigot will be first well packed in with spun yarn leaving 25 mm from the lip of the socket for the lead.  The joint shall then be lead caulked as described in detail under jointing of S. C. I. soil, waste and vent pipes.

Fig.90 Holder Bat Clamp

Fig. 9 Holder Bat Clamp

8.27. specifications for cast iron fittings for rain water pipes

8.27.1. C.I. fittings - C. I. fittings such as bends of various degrees, heads, offsets of different projections, branches and shoes shall conform to IS: 1230-1979.  The general specifications for these as described shall apply.

Bends shall be of the nearest standard degree as actually required at site. Heads shall be of the flat or corner type as required.  Offsets shall be of the projection as stipulated in the description of the item. Branches shall be single or double as described in the item and shall be of the nearest standard degree as actually required.  Standard shoes shall be of overall vertical length, 180 mm for 75 mm dia., 205 mm for 100 mm dia and 275 mm for 150 dia sized pipe from top of socket to lowest tip of shoe.  Shoes of longer lengths if used shall be in lengths from top of socket to lowest tip of shoe of 300 mm, 375 mm, 450 mm, or 600 mm, as actually required at site.

8.27.2. Dimensions - The fittings shall be of the diameter specified in the description of the item.

The thickness of the fittings and details of spigots and sockets shall be same as those of the corresponding size of straight pipes.  The fittings shall be supplied without ears unless otherwise specifically mentioned in the item.  The fittings shall be factory painted with a tar basis composition both inside and outside which shall be smooth and tenacious. Every fitting shall ring clearly when struck all over with a light hard hammer. The fittings shall be of standard size and their individual weights shall conform to the weights given in the Table 8.

Table 8 Weight of C.I Rain water pipe fittings

Sl No

Description

75 mm dia (weight in kg)

100 mm dia (weight in kg)

150 mm dia (weight in kg)

Unit

1

2

3

4

5

6

1

Bends (Plain)

3.20

4.50

9.10

Each

2

Offset (Plain)

 

 

 

 

a

55 mm projection

2.70

5.00

8.20

Each

b

75 mm projection

3.20

5.50

9.10

Each

c

115 mm projection

4.10

5.90

9.50

Each

d

150 mm projection

4.50

6.40

10.40

Each

e

225 mm projection

5.00

7.30

11.80

Each

f

300 mm projection

6.00

8.60

12.70

Each

3

Branches (Plain)

 

 

 

 

 

Single

5.00

7.30

14.50

Each

 

Double

6.80

10.00

19.10

Each

4

Standard shoes (Plain)

3.20

4.10

8.60

Each

5

Longer shoes (Plain)

 

 

 

 

a

300 mm

3.20

5.00

-

Each

b

375 mm

4.10

5.50

-

Each

c

450 mm

5.50

6.40

-

Each

d

600 mm

7.30

8.60

-

Each

6

Heads

6.40

6.80

11.30

Each

7

Extras

 

 

 

 

a)

For ears cast on any fitting and short pipes.

0.90

0.90

1.35

Each

b)

For inspection doors fitted on any fitting

1.80

1.80

2.25

Each

Note: (1) The above table applies only to rain water fittings which are part of pipe lines fixed on wall face. Permissible tolerance in weight of fittings shall be 5 %.(2) For fittings to be used with pipe lines to be embedded in masonry, specifications shall correspond with those of pipe fittings for soil, waste and vent pipes. For their weights, specifications under S.C.I.Soil waste and vent pipes may be referred to.

8.27.3. Fixing and jointing - Shall be as specified 8.25.3

8.27.4. Finish - Shall be as specified in 8.25.3.5.

8.27.5. Measurements - The fittings shall be measured by numbers.  Where longer shoes are used in lieu of standard shoes specified in the description of the item, they shall be measured as standard shoes of 180 mm, 205 mm and 275 mm for 75 mm dia, 100 mm dia and 150 mm dia respectively in number and the extra lengths of the shoes shall be measured and paid for under the corresponding size of pipes.

8.27.6. Rate - The rate shall include in the case of fittings fixed on the face of wall, the cost of all materials and labour involved in all the operations described above including jointing but excluding the supply and fixing the M. S. holder bat clamps in walls and the anchoring concrete. Unless otherwise specified in the description of the item, the rate shall apply for fittings without access doors. In the case of fittings forming part of a rain water pipe line embedded in masonry, the rate shall be for supplying and embedding in masonry, the rate shall be for supplying and embedding the fittings in masonry but shall not include for the jointing and lead caulking which shall be paid for separately.

8.28. specifications for asbestos cement rain water pipes

A. C. rain water pipes shall be fixed with standard holder bat clamps.

8.28.1 A. C. pipes - The pipes shall conform to IS: 1626 (Part-1)-1994. These shall be straight, true and smooth and regular in thickness.  To determine the straightness of a pipe it shall be rolled along a plane surface in such a manner that the socket over hangs on one edge of the plain surface.  The gap between the barrel of the pipe and the plane surface shall not exceed the limits indicated below:

Length of pipe in metre

Gap in mm

0.5

3

1.0

3

1.5

5

2.0

5

3.0

6

They should be sound, homogeneous and free from cracks and other flaws.

8.28.2. Dimensions - A. C. rain water pipes shall be of the diameter specified in the item. The pipes are available in lengths of 0.5 m, 1 m, 1.5 m, 2 m and 3 m excluding the depth of socket.  The pipes shall be fixed in lengths of 3 metres as far as possible.  The thickness of pipes and tolerances on their thickness shall be as shown in Table 9 below:

Table 9 Thickness of pipes and pipe fittings and tolerances on thickness

Nominal diameter of pipe and pipe fittings in mm

Thickness of pipe or pipe fittings in mm

Tolerances on thickness in mm

50

6.5

± 1.0

60

6.5

± 1.0

80

8.0

± 1.0

100

8.0

± 1.0

150

9.5

± 1.5

8.28.3. Fixing and jointing - Pipes shall be secured to face of the wall, below all joints by standard holder bat G. I. clamps. The bat clamps shall consist of a cast iron base with a projecting “I” shaped lug, to the web of which the two semi-circular halves of the 1.8 mm thick G. I. sheet clamp or 3 mm thick M. S. clamps are bolted.  The base of the holder bat clamp shall be screwed on a pair of wooden plugs fixed in the wall with screws of designation No. 18 of slotted counter sunk head wood screws driven through the holes in the base. The screws shall be not less than 75 mm long for 80 mm diameter pipes and 100 mm long for 100 mm dia pipes.  The plugs shall be fixed in the wall to a depth of 15 cm, in cement mortar 1:2 (1 cement: 2 fine sand) centrally to the holes.  In the base of the bat clamps and with their front face projecting to such a length from the brick face that when the bat clamp is fixed, the outer face of its base shall be 11 x 5 cm wide at face increasing to 16 x 7 cm width at rear and shall be 7 cm deep throughout. The bat clamps and its method of fixing to the wall is shown in Fig. 9.  The bat clamps shall be well galvanised.

The spigot of the upper pipe shall be properly fitted into the socket of the lower pipe, such that there is uniform, annular space for filling with the jointing material.  One-third depth of this annular space between socket and spigot shall be filled in with spun yarn soaked in bitumen such as cut back bitumen of approved quality and properly pressed with caulked tool.  The remaining 2/3rd depth of the joint shall be filled in with stiff cement mortar 1:2 (1 cement : 2 coarse sand) and shall be pressed with caulking tool and finished smooth at top at an angle of 45 degree slopping up.  This will be cured for a period of 7 days by tieing a piece of gunny bag, four fold, to the pipes and keeping it wet.

8.28.4. Finish - The finished pipe line shall be truly vertical or to lines and slopes as directed and shall be at a uniform distance of 40 mm from the finished face of the wall.

8.28.5. Measurements - The pipes shall be measured net when fixed correct to a cm excluding all fittings along its length.  When collars are used, these shall be measured along with and paid as pipes and no extra shall be paid for collars or for fixing them to wall with bat clamps.  No allowance shall be made for the portions of pipe lengths centering the sockets of the adjacent pipe or fittings.  The above will apply to both cases i.e. whether the pipes are fixed on wall face or the pipes are embedded in masonry. No deduction shall be made in the former case from the masonry measurements for the volume of concrete blocks embedded therein.

Similarly no deduction shall be made for the volume occupied by the pipes from the masonry when the former are embedded in the latter.

8.28.6. Rate - The rate shall include the cost of all materials and labour involved in all the operations described above including jointing but excluding the supply and fixing up wall plugs and bat clamp which shall be paid for separately.

8.29. specifications for asbestos cement pipe fittings

8.29.1. A. C. fittings - By the term fittings are meant A. C. specials such as bends of various degrees, heads, and offsets of different projections, branches and shoes.  The general specifications for these shall conform to those described. These shall conform to IS: 1626 (Pt. 1) and shall be of approved manufacturer.

8.29.2. Dimensions - The fittings shall be of the type, diameter and size specified in the description of the item.  The thickness of the fittings and details of spigots and sockets shall be the same as those of the corresponding size of straight pipes.  The fittings shall be of standard size and their individual thickness and tolerance on thickness shall be as per table 9. The fittings shall also conform to IS: 1626 (Pt. 1).

8.29.3. Fixing and jointing - The specifications for A. C. Pipes shall also apply to fittings.

8.29.4. Measurements - The fittings shall be measured in numbers.

8.29.5. Rate - The rate shall include the cost of all materials and labour involved jointing but excluding the supply and fixing of wall plugs and bat clamps, which shall be paid for separately. Unless otherwise specified in the description of the item, the rate shall apply for plain fittings without access doors.

8.30. SPECIFICATIONS for thermal insulation for roofing

8.30.1. With cellular concrete

8.30.1.1. Types and grades - Cellular concrete is a lightweight concrete formed by producing gas or air bubbles in cement slurry or cement sand slurry.  Cellular concrete shall conform to IS: 6598-1972 and shall be of following two types depending on the manner of manufacture.

a). Type I: High pressure steam cured (autoclaved) materials in the form of precast blocks.

b). Type II: Materials cured under natural conditions (that is under ambient pressure and temperature) by water.  The material may be either cast in situ or may be in the form of precast blocks.

Grades – Each of these two types of the material shall have three grades, namely:

Grade A – Light weight cellular concrete;

Grade B – Medium weight cellular concrete and;

Grade C – Heavy weight cellular concrete.

8.30.1.2. Materials

a)  Aggregate - A variety of siliceous fines, such as ground quarts sand shale, flyash and granulated slag may be used in the manufacture of cellular concrete.

  1. Water and binder shall conform to specifications.

c)  Gassing agents - Organic foaming agents based on resin soap, glue, surface active agents, or fine aluminum powder sine, dust, calcium carbide, calcium by prochlorite etc. may be used for gassing the concrete.

8.30.1.3. Dimensions - The dimensions of the type I and type II cellular concrete block shall be either 50 or 60 cm in length, 20, 25 or 30 cm in width and 8.5, 10, 15, 25 or 40 cm in thickness.

8.30.1.4. Tolerance - A tolerance of ± 3 per cent shall be allowed on width and height and ± 1 per cent on thickness.

8.30.1.5. Requirement for cellular concrete

Table 10

Sl.No

Characteristics

Grade A

Grade B

Grade C

Test

1

Density in kg/cum

Upto 300

301 to 400

401 to 500

BIS 5688

2

Crushing Strength in kg/sq. cm.

 

 

 

 

 

(Type I)

7.0

12.0

20.0

-do-

 

(Type II)

4.5

6.0

9.0

 

3

Thermal conductivity in kw/cm deg C at 50 deg. C mean temperature

0.85

 

1.0

0.7

--do –

 

4

Capillary absorption not to exceed 20% in case of type I cellular concrete when tested as per Appendix A of IS : 6598

0.7

0.85

1.0

BIS 3346

8.30.1.6. Sampling - In a consignment, cellular concrete of the same type and grade and manufactured approximately in the same period shall be grouped to form a lot.  If it is in the form of blocks, a lot shall be made up of not more than 1000 blocks.  If the material is in situ, not more than 10 tons of materials shall constitute a lot. If the material is transported in Lorries and received as such, the material in lorry (or vehicle load) may be termed as lot. Each lot shall be tested for all the requirements separately. If the lot is made up of precast blocks, the number of sample blocks to be tested shall be selected at random as per the following Table 11.

Table 11

Lot size

Sample size (blocks) to be sampled

Permissible no. of defectives (visual) and dimension requirements

Upto 100

5

0

101 to 300

8

0

301 to 500

13

0

501 to 1000

20

1

8.30.1.7. General - Cellular concrete if done with precast blocks shall be laid on terrace slab after thoroughly cleaning the surface.  The blocks shall be laid over a layer of 12 mm average thick cement mortar 1:6 (1 cement: 6 coarse sand) and the joints shall also be filled properly with neat cement slurry. The joints shall be staggered.

8.30.1.8. Measurements - Lengths and breadth of the roofing insulation shall be measured correct to a cm and the surface area worked out in square metre of the finished work.

No deduction shall be made for openings of areas up to 40 square decimetre.  No extra payment will be made for any extra material or labour involved in forming such openings. For openings exceeding 40 square decimetre in area, deduction for the full opening will be made, but nothing extra will be paid for any extra material or labour involved in forming such openings.

Boarding fixed to curved surfaces in narrow widths shall be measured and paid for separately.  Circular cutting and waste shall be measured and paid for separately in running metres.

8.30.1.9. Rate - The rate shall include the cost of all materials and labour in providing cellular concrete.

8.30.2. With bounded mineral wool

8.30.2.1. Material - The material shall be mineral wool made from rock slag or glass processed from a

molten state into fibrous form and shall be bonded with a suitable binder.  Bonded mineral wool shall conform to specifications of group I of IS: 8183-1993.

8.30.2.2. Dimensions - The bonded mineral wool shall be supplied in width of 50, 60, 75 and 100 cms, length of 100, 120, and 140 and the thickness of the bonded mineral wool shall be 25, 40, 50, 65 or 75 mm.

8.30.2.3. Tolerances - For width and length, the dimensional tolerances of the bonded mineral wool slabs shall be ½ % or 3 mm and for thickness, the tolerance shall be 3 mm. An excess, in all dimensions is permitted.

Requirements for bonded mineral wool

                                                                 Table 12

Sl.No

Characteristics

Group I

Test reference

1

Bulk density

12 to 15 kg/cum

IS : 3144

2

Recover/after compression

90% of original thickness

Appendix A of IS: 8183

3

Shot content max

500 micron-5%

IS : 3144

 

250 micron – 15%

 

 

4

Moisture content and abrasion

2%

IS : 3144

5

Incombustibility

Incombustible

IS : 3144

6

Thermal conductivity deg. C at mean temperature 50oC

0.49 mw per cm

IS : 3346

7

Sulphur content

Not more than 0.6%

IS : 3144

8.30.2.5. Sampling - The number of slabs as per the Table – 13 will be selected at random from the lot.  Tests for determination of all characteristics specified above shall be conducted on each of the test specimen as drawn above. The lot shall be declared as conforming to the requirements of this specification, if the different tests results obtained under above para meet the corresponding requirements given in the standard individually.

Table 13

Lot size  N

No. of slabs to be selected  N

Upto 200

5

201 to 300

6

301 to 500

7

501 to 800

8

801 to 1300

9

1301 and above

10

8.30.2.6. General - Bonded mineral wool insulation can be either laid over false ceiling or alternatively it can be fixed to the ceiling when the space above false ceiling is being used for carrying return air.  In the first case the bonded mineral wool can either be fixed with suitable adhesive to the false ceiling board or else it can simply be rolled over the suspended false ceiling. In the second case when space above false ceiling is to be used for carrying return air 1.5” x 1.5” slotted angle (3” length) shall be fixed to the ceiling by means of rawl plugs at 2.0” spacing.  Draw 14 gauge tie wires from the slots. Make a mat of mineral wool insulation backed with scrim cloth with a light coating of Plaster of Paris or polythene faced hessian and 24 g x 1” wire mesh netting.  The joints of wire netting should be butted and tightly laced down with G. I. wire.  Stretch the mat tightly across the angles holding it in place by means of tie wires.

8.30.2.7. Measurements - Length and breadth of the roofing insulation shall be measured correct to a cm and the surface area worked out in square metre of the finished work. No deduction shall be made for openings of areas up to 40 square decimetre.  No extra payment will be made for any extra material or labour involved in forming such openings. For openings exceeding 40 square decimetre in area, deduction for the full opening will be made, but no extra will be paid for any extra material or labour involved in forming such openings. Boarding fixed to curved surfaces in narrow widths shall be measured and paid for separately.  Circular cutting and waste shall be measured and paid for separately in running metres.

8.30.2.8. Rate - The rate shall include the cost of all materials and labour in providing bonded mineral wool.

8.30.3. With expanded polystyrene

8.30.3.1. Material - Expanded polystyrene shall conform to IS : 4671-1984.  It is of two types as given below:

  1. Type N – Normal
  2. Type SE – It shall be of self extinguishing type when tested in accordance with Appendix E of IS: 4671-1984.

8.30.3.2. Dimensions - The size of the finished boards shall be 1.0 x 0.5 m or as specified and having a thickness of 15, 20, 25, 40, 50, 60, 75 or 100 mm.

8.30.3.3. Tolerances - The tolerances on length, width and thickness of the finished board shall be ± 2 mm.Requirements for expanded polystyrene for general use.

Table 14

Sl No

Characteristics

Requirements at various nominal apparent densities in kg / cum

Test reference

 

 

15

20

25

30

 

1

Thermal conductivity (K.value) at 50oC in mw/cm deg.

0.41

0.39

0.37

0.35

IS : 3346

2

Compressive strength of 10% deformation in kg/sq.cm Min.

0.7

0.9

1.1

1.4

Appendix  A of IS: 4671

3

Cross breaking strength in kg/sq.cm Min

1.4

1.6

1.8

2.2

Appendix B of IS : 4671

4

Water vapour permeance in g/sqm 24 hrs. Max

50

40

30

20

Appendix C of IS : 4671

5

Thermal stability percent max.

1

1

1

1

Appendix D of IS : 4671

8.30.3.4. Sampling - In a single consignment all the items of the same type, shape and dimensions belonging to the same batch of manufacture shall be grouped together to constitute a lot. For the purpose of judging conformity to the requirements each lot shall be considered separately. The number of sample items for this purpose shall depend on the size of the lot and shall be in accordance with Col. 1 & 2 of table No. 15 given below.  The sample shall be taken at random from the lot Table 15

No. of items in the lot

No. of sample items

Permissible number of defective sample items

Upto 25

3

0

26 to 100

5

0

101 to 300

8

0

301 to 1000

13

0

1001 to 3000

20

1

3001 and above

32

2

All the sample items selected from the lot shall be tested for all requirements of the specifications.  Any item failing in one or more of the requirements shall be regarded as defective.

8.30.3.5. General - Expanded polystyrene can either be fixed with suitable adhesive to the false ceiling board or else it can simply be rolled over the suspended false ceiling.

8.30.3.6. Measurements - Length and breadth of the roofing insulation shall be measured correct to a cm and the surface area worked out in square metre of the finished work.

No deductions shall be made for openings of areas up to 40 square decimetre. No extra payment will be made for any extra material or labour involved in forming such openings. For openings exceeding 40 square decimetre in area deduction for the full opening will be made, but nothing extra will be paid for any extra material / labour involved in forming such openings.

8.30.3.7. Rate - The rate shall include the cost of material and labour in providing and fixing the polystyrene boards.

8.30.4. With exfoliated vermiculite

8.30.4.1. Material - Exfoliated vermiculite consists of vermiculite mineral which has been expanded many times its original volume after being subjected to high temperature (700 degree C to 1000 degree C).

8.30.4.2. It is utilised as a thermal insulation material after mixing it with a cementations material.

8.30.4.2.1. Requirements of exfoliated vermiculite for general use 

Exfoliated vermiculite in loose fill condition should conform to following

Sl

No

Characteristics

Type I

Type II

Type III

Type IV

1

Density in kg/cum – Min.

56

64

80

96

 

  -do-       - Max.

112

128

144

160

2

Thermal conductivity at mean temp. 25oC in mw/cm deg.C

0.72

0.72

0.72

0.72

 

Size Designation

9.51 mm

4.76 mm

2.38 mm

1.18 mm

595 mcn

297 mcn

149 mcn

 

Min

Max

Min

Max

Min

Max

Min

Max

Min

Max

Min

Max

Min

Max

Type I

0

40

30

90

65

98

85

100

 

 

 

 

 

 

Type II

 

 

0

95

20

80

75

99

90

100

97

100

 

 

Type III

 

 

 

 

0

10

20

70

65

95

75

98

90

100

Type IV

 

 

 

 

 

 

0

5

15

65

60

98

90

100

8.30.4.2.2. Exfoliated vermiculite after being mixed with a cementitious material should conform to following:

Sl No

Characteristics

Requirements

1

Consistency

35 to 45% or 178 to 229 mm

2

Dry covering capacity in sqm of 100 kg of material 1 cm thick

34 sqm

3

Compressive strength at 5% deformation min

103.5 KN/sqm

4

Liner shrinkage after 24 hrs at 1800 Deg F max.

3%

5

Thermal conductivity max. at mean temperature 95oC.

1.37 mw/cm deg.C

8.30.4.3. Sampling & testing - If any of the test date obtained on the samples tested fail to conform to the requirements given above, the material shall be rejected.

8.30.4.4. General - Exfoliated Vermiculite along with cementitious material is mixed with water in the required proportion (as specified by manufacturers). This mix is to be immediately spread over the terrace slab in prescribed thickness. No curing need be done.  After laying the insulation, the entire surface shall be cement plastered with cement mortar 1:4 of 20 mm thickness.

8.30.4.5. Measurements - Length and breadth of the roofing insulation shall be measured correct to a cm and the surface area worked out in square metre of the finished work.

No deduction shall be made for openings of areas up to 40 square decimetre. No extra payment will be made for any extra material or labour involved in forming such openings. For openings exceeding 40 square decimeter in area, deduction for the full opening will be made, but nothing extra will be paid for any extra material or labour involved in forming such openings. Boarding fixed to curved surfaces in narrow widths shall be measured and paid for separately.  Circular cutting and waster shall be measured and paid for separately in running metres.

8.30.4.6. Rate - The rate shall include the cost of all materials and labour in providing exfoliated vermiculite.

Annexure 7-A.1

SPECIFICATIONS FOR GALVANISED STEEL SHEETS

Dimensions

Sizes of plain sheet - The pain sheets shall be supplied in any combination of the following lengths, widths and thicknesses.

a) Length : 2500 and 3000 mm

b) Width : 900 and 1000 mm

c) Thickness : 0.50, 0.63, 0.80, 1.00, 1.25 and 1.60 mm

In case of sheets supplied in coil, the internal diameter of coil shall be 450, 510, 610 mm and the mass of each coil shall not exceed 12 tonne.

Coils weighing more than 12 tonnes may be supplied subject to mutual agreement between the contracting parties.

Corrugated sheets

Length - The length of the corrugated sheets shall be as follows; 2500, 3000 mm

Zinc coating - The weight of coating referred to in this specification shall represent the total weight of Zinc both sides inclusive. On any sample selected at random from the delivery, one set of three samples each 50 x 50 mm or 50 mm diameter shall be selected at random from one sheet for every 500 G. S. sheets, the coating for the different classes shall be within the limits specified in table below:

Table 1 Mass of coating (Total both sides)

Grade of coating

Minimum average coating Triple spot test g/sqm

Minimum coating Single spot test* g/sqm

750

625

550

600

500

425

450

350

300

375

275

250

* Minimum individual value obtained in triple spot test.

Mass - The mass of sheets and coils shall be calculated as given in Table 2 on the basis of nominal dimensions and mass of Zinc coating.

Table 2 Calculation of mass of sheets or coils

Type of materials

Order of calculation

Method of calculation

Number of numerals in resultant value

Sheet

Mass of single sheet

Nominal mass of single sheet plus mass of zinc coating

Rounded off to 4 effective figures.

 

Total mass

Mass of single sheet (kg) x number of sheets

Rounded off to integral value of kg

Coil

Unit mass of coil

Unit mass of sheet (kg/m3) x width (mm) x10

Rounded off to 3 effective figures

 

Mass of single coil

Unit mass of coil (kg/m) x length (m)

 

 

Total mass (kg)

Total mass of each coil

Integral number of (kg)

 Note: Nominal mass of single shall be calculated by calculating the volume of the sheet and multiplying the same with density of sheet (density 7.85 g/cubic cm) and rounding the same to 4 effective figures.

  1. Mass of the coating shall be calculated by multiplying the surface area of single sheet with indicated nominal coating mass (g/square metre) as shown for triple spot test (Table 1)
  2. For calculation of corrugated sheet mass, the width before corrugation shall be considered while calculating the area.

Corrugations - The depth of corrugation shall be 18 mm and shall have a pitch of 75 mm (nominal).

The number of corrugations shall be 8, 10 or 11 per sheet. The overall width of the sheet  before and after corrugation shall be as the dimensions given in table :

Table 3 Details of corrugations

Number of Corrugations

Nominal overall width of sheet measured between crowns of  Outside corrugations

Before corrugation (mm)

After corrugation (mm)

10

900

800

11

1000

885

Annexure 8-A.2

SPECIFICATIONS FOR BITUMEN FELTS (FIBRE HESSIAN BASE)

Weights - The weights of the ingredients used in the manufacture of bitumen felts per 10 sqm shall be not less than those specified in Table 4.

Table 4 Minimum weights of bitumen felts

Sl.No

Type of felt

For 10 Sq.m

Untreated base

Saturant

Constant

Bitumen content

Total weight of the finished bitumen felt in dry condition with mica dusting powder Min. kg

 

 

Kg

Kg

Kg

Kg

kg

(1)

Fibre base

 

 

 

 

 

i

Type 2 Grade 1

5.0

5.7

10.7

11.9

21.9

ii

Type 2 Grade 2

4.0

4.5

21.8

17.1

30.8

 

iii

Hessian Base

Type 3 Grade 1

 

2.3

 

1.8

 

17.7

 

12.1

 

22.3

iv

Type 3 Grade 2

2.3

1.8

31.8

20.2

36.4

Note: 1. The weight of the untreated base shall be taken as in the dry condition

         2.  Includes allowance for 0.5 kg minimum mica dusting powder in dry condition.

Sampling - All the rolls of the same type and grade and from the same batch of manufacture, in one consignment shall constitute a lot.

The conformity of the lot to the requirements of the standard shall be determined on the basis of inspection and tests carried out on the samples selected from the lot.The number of rolls to be taken from the lot shall depend upon the size of the lot and shall be in accordance with the Table 5.

Table 5 Sample size

No. of rolls in the lot

No. of rolls to be selected in the sample

Permissible no. of defective rolls

Sub-sample sizes, no. of rolls to be selected.

Upto 100

5

0

2

101 to 150

8

0

3

151 to 300

13

0

4

301 to 500

20

1

5

501 to 1000

32

2

6

1001 to 3000

50

3

8

3001 and above

80

5

10

Note:  (1) All the rolls taken as per column 2 shall be inspected for width, length and visible external defects. (2) The rolls as per column 4 shall be tested for breaking strength, pliability, storage sticking, heat resistance, and water absorption and pressure head. These rolls shall be taken at random from the lot, and in order to ensure randomness of selection, random number tables may be used.  In case random number tables are not available, the following procedure may be adopted for the selection of the rolls. Starting from any roll in the lot count them as 1, 2, 3 and so on, in one order. Every rth roll thus counted may be selected till the requisite number of rolls for the sample is obtained, r being the integral part of N/n, where N is the number of rolls in the lot and in number of rolls to be selected in the sample. From each of the rolls one piece 3 m long and the full width of the felt shall be cut out for preparing test specimens. The first 2 m of the roll shall not be selected for this purpose.  The lengths of felt so selected shall be free from abnormal defects and shall be truly representative of the whole consignment.  The selected pieces of felt shall be despatched without breakage or distortion, wrapped up in water proof paper or other similar materials so as to cause no damage to the material during transit.  In case the material has stuck together, no heat shall be applied to separate the layer but the whole roll shall be sent for testing and the fact shall be reported.

Tests - The samples, when tested as per IS: 1322 shall conform to the requirements given in Table 6.

Table 6

Sl.

No

Type of felt

Breaking strength kg

Pliability test

Storage sticking test

Heat resistance test

Pressure head test

Water absorption test

Warp way

Weft way

1

Type 2 (all grades

95

60

i) The roll shall not show cracks on unrolling

 

 

 

ii) Consider any surface rupture exceeding 5 mm in length as failure

The test piece shall be examined after cooling

 

 

After release of the load, the layers of felt shall be capable of being separated without damaging in any way

The test piece shall show no sign of melting of the bitumen compound

The test piece shall show no sign of leakage

    1. %

 

 

 

 

 

 

 

 

 

 

 

 

 

2

Type 2 (all grades)

135

90

i) The roll shall not show cracks on unrolling

 

 

 

ii) Consider any surface rupture exceeding 5 mm in length as failure

The test piece shall be examined after cooling

 

 

After release of the load, the layers of felt shall be capable of being separated without damaging in any way

The test piece shall show no sign of melting of the bitumen compound

The test piece shall show no sign of leakage

2.00%

 

Criteria for conformity - The lot shall be considered to be in conformity with the requirements of the standard if the following conditions are satisfied:

  1. The number of rolls found defective with respective to width, length and visible external defects do not exceed the corresponding number given in column 3 of table 15.
  2. From the observed values of breaking strength, the average X and the range R are calculated for each direction (that is, warp way and weft way) separately and the value of the expression X – 0.6 R is found to be greater than or equal to the applicable specified value.

Note: 1 Average X is the value obtained by dividing the sum of the observed values by the number of observed values.

Note: 2 Range R is the difference between the maximum and minimum in a set of observed values.

  1. For all the other characteristics (except breaking strength) all the test pieces satisfy all the requirements of the characteristics individually.

Annexure 8-A.3

SPECIFICATIONS FOR GLASS FIBRE BASE BITUMEN FELT  (Clause 8.17.1.1)

Weight - The weight of the ingredients used in the manufacture of glass fibre felts for 10 square metre shall be not less than those specified in table 7.

Table 7 Minimum weight of bitumen glass fibre base felt for 10 square metre

Sl.No

Type of felt

Untreated base Kg

Treated base Kg

Coatant Kg

Total weight in dry condition including surfacing materials kg

1

Type 2 Gr. 1

0.4

 

15.3

18.0

Sampling - All the rolls of the same type and grade and from the same batch of manufacture, in one consignment shall constitute a lot.  The conformity of the lot to the requirements of this standard shall be determined on the basis of the inspection and test carried out on the samples selected from the lot. The number of rolls to be selected from a lot shall depend upon the size of the lot and shall be in accordance with Table 8.

Table 8 Sample size and criterion of conformity

No. of rolls in the lot

No. of rolls to be selected in the sample

Permissible no. of defective rolls

Sub-sample size, no. of rolls to be selected

Upto 100

5

0

2

101 to 150

8

0

3

151 to 300

13

0

4

301 to 500

20

1

5

501 to 1000

32

2

6

1001 to 3000

50

3

8

3001 and above

80

5

10

Note:1. All the rolls taken as per columns 2 shall be inspected for width, length and visible

external defects.

2. The rolls taken as per column 4 shall be tested for breaking strength, pliability, storage sticking, heat resistance, and water absorption and pressure head.

These rolls shall be taken at random from the lot and in order to ensure randomness of selection, random number tables may be used.  In case random number tables are not available, the following procedure may be adopted for the selection of the rolls.

Starting from any roll in the lot count as 1, 2, 3…r and so on, in one order. Every rth roll thus counted may be selected till the requisite number of rolls for the sample is obtained, r being the integral part of N/n, where N is the number of rolls in the lot and n the number of rolls to be selected in the sample.

From each of these rolls one test sample 3 m long and the full width of the felt shall be cut out for preparing test specimens. Test samples shall not be taken from damaged portion of the rolls, if any, the required number of test specimens shall be taken from each of the test sample and subjected to the corresponding tests.

Tests - The sample, when tested as per IS: 7193 shall conform to the requirements given in Table 9.

Table 9

Type of felt

Minimum breaking strength in kg

Pliability test

Storage sticking test

Heat resistance test

Pressure head test

Water absorption test, Max

Wrap way

Weft wat

Table 2 Grade 1

50

30

i) The roll shall not show cracks on unrolling

 

 

ii) Consider any surface rupture exceeding 5 mm in length as failure

The test piece shall be examined after cooling

 

After release of the load, the layers of felt shall be capable of being separated without damaging in any way

The test piece shall show no sign of melting of the bitumen compound

 

--

The test piece shall show no sign of leakage

 

 

--

    1. %

 

 

 

 

--

 

Criteria for conformity - The lot shall be considered to be in conformity with the requirements of the standard if the following conditions are satisfied:

  1. The number of rolls found defective with respect to width, length and visible external defects, do not exceed the corresponding number given in column 3 of Table 8.
  2. From the obsessed values of breaking strength, the average X and the range R are calculated for each direction (that is,  warp way and weft way) separately and the value of the expression X – 0.6 R is found to be greater than or equal to the application specified value.

Note:

1. Average X is the value obtained by dividing the sum of the observed value by the number of observed values.

2. Range R is the difference between the maximum and minimum is a set of observed values.

  1. For all the other characteristics (except breaking strength), all the test pieces satisfy all the requirements of the characteristics individually.

Annexure 8-A.4

LIST OF BUREAU OF INDIAN STANDARDS (IS)*

Sl.No.

IS: No.

Subject

1

73-1992

Specification for Paving Bitumen (2nd Revision)

2

277-1992

Galvanised Steel Sheet (Plain and Corrugated) (5th Revision)

3

458-1988

Specification for Precast Concrete Pipes (with and without reinforcement) (3rd Revision)

4

459-1992

Corrugated and Semi Corrugated Asbestos Cement Sheets (3rd Revision)

5

651-1992

Salt Glazed Stone Ware Pipes and Fittings (5th Revision)

6

702-1988

Specification for Industrial Bitumen (2nd Revision)

7

1199-1959

Methods of Sampling and Analysis of Concrete (Reaffirmed 1991)

8

1200-1973

Method of Measurement of Building and Civil engineering Works

 

(Part IX)

Part IX : Roof Covering (including Cladding) (Reaffirmed 1992) (2nd Revision)

9

1200-1973

Method of Measurement of Building and Civil engineering Works

 

(Part X)

Part X : Ceiling and Lining (Reaffirmed 1992) (2nd Revision)

10

1202-1978

Determination of Specific Gravity (Reaffirmed 1990)

11

1203-1978

Determination of Penetration (Reaffirmed 1990)

12

1205-1978

Determination of Softening Point ((Reaffirmed 1988)

13

1208-1978

Determination of Ductility (Reaffirmed 1988)

14

1209-1978

Determination of Flash Point and Free Point (Reaffirmed 1988)

15

1211-1978

Determination of Water Content ((Dean and Stark Method) (Reaffirmed 1988)

16

1212-1978

Determination of Loss on Heating (Reaffirmed 1988)

17

1216-1978

Determination of Solubility in Carbon Disulphide Trichloroehtylene (Reaffirmed 1988)

18

1230-1979

Cast  Iron Rain Water Pipes and Fittings (Reaffirmed 1991) (2nd Revision)

19

1322-1993

Specifications for Bitumen Felts for Water Proofing and Damp Proofing (4th Revision)

20

1367-1983 (Part XIII)

Technical Supply Conditions for Threaded Steel Fasteners

Part XIII : Hot Dip Galvanized Coating on Threaded Fasteners (Reaffirmed 1991) (2nd Revision)

21

1609-1991

Code of Practice for Laying Damp Proof Treatment Using Bitumen Felts (2nd Revision)

22

1626-1994 (Part 1)

Specifications for Asbestos Cement Building Pipes and Pipe Fittings, gutters, and Gutter Fittings and Roofing Fittings : Part : 1 : Pipe and Pipe Fittings (2nd Revision)

23

1626-1994 (Part II)

Specifications for Asbestos Cement Building Pipes and Pipe Fittings, Gutters and Gutter Fittings and Roofing Fittings : Part II : Gutter and Gutter Fittings (Reaffirmed 1992) (2nd  Revision)

24

1626-1994 (Part III)

Specifications for Asbestos Cement Building Pipes and Pipe Fittings, Gutters and Gutter Fittings and Roofing Fittings : Part : III : Roofing Accessories (2nd Revision)

25

2115-1980

Code of Practice for Flat Rood Finish : Mud Phuska  Reaffirmed  1992) (2nd Revision)

26

2633-1986

Methods of Testing Uniformity of Coating on Zinc Coating  Articles (Reaffirmed 1992) (2nd Revision)

27

2645-1975

Specification for Integral Cement Water Proofing Compounds (Reaffirmed 1992) (Ist Revision)

28

3007-1964 (Part I)

Code of Practice for Laying of Asbestos Cement Sheets : Part I : Corrugated Sheets (Reaffirmed 1991)

29

3007-1965 (Part II)

Code of Practice for Laying of Asbestos Cement Sheets :

Part II : Semi-corrugated Sheets (Reaffirmed 1991)

30

3144-1992

Mineral Wool Thermal Insulation Materials Methods of test (2nd Revision)

31

3346-1980

Method of the Determination of Thermal Conductivity of  Thermal Insulation Materials (two slab guarded hot plate method) (Reaffirmed 1990) (Ist Revision)

32

3348-1965

Specification for Fibre Insulation Boards (Reaffirmed 1990)

33

3384-1986

Specification for Bitumen Primer for Water Proofing and Damp Proofing (Reaffirmed 1990) (1st Revision)

34

4671-1984

Expanded Polystyrene for Thermal Insulation Purposes (Reaffirmed 1990) (1st Revision)

35

5688-1982

Method of Test of Preformed Block Type and Pipe Covering Type Thermal Insulations (Reaffirmed 1990) (1st Revision)

36

6598-1972

Cellular Concrete for Thermal Insulation (Reaffirmed 1990)

37

7193-1994

Specification for Glass Fibre Base Coal Tar Pitch & Bitumen Felts (Amendment 1) (1st Revision)

38

8183-1993

Binded Mineral Wool (1st Revision)

*****