05-ROOFING &CEILING



ROOFING AND CEILING

Requirements

  1. Roof shall not be pitched at a flatter slope than 1 vertical to 5 horizontal.
  2. The normal pitch adopted shall usually be 1 vertical to 3 horizontal.
  3. The purlins shall not be spaced at more than the following distances.

Table : Maximum spacing of purlins

Thickness of CGS sheet (mm)

Maximum spacing of purlins (m)

1.00

2.0

0.80

1.8

0.63

1.6

  1. The top surfaces of the purlins shall be uniform and plane. They shall bepainted before fixing on top.
  2. Embedded portions of wooden purlins shall be provided with anti termitetreatment.
  3. The galvanised coating on J and L hooks should conform to IS: 1367-Part 13.The mass of coating per square meter of the surface is given in table.

Table: Mass and equivalent thickness of coating

Minimum mass (gm/m2) Average thickness (μm) Individual thickness (μm)
CZC XZCXZ XZCZ
ZCZXCZ XZCZ XZCZ
ZXCZXC ZXCXZC XZC
ZXCZX XZCZ ZXCZ

The end laps of the ridges and hips and between ridges and hips shall also benot less than 20 cm.

The ridges and hips shall be of 60 cm overall width plain GS sheet, 0.6 mm or0.8 mm thick as given in the description of the item and shall be properly bentin shape.

 Table: Number and length of bolts and washers

Sl. No Situation No. of bolts and washers Length of bolts
1 At horizontal (end) lapsof sheets, at eaves whenfiller pieces are usedand at ridge whensheets and ridge piecesare secured by the samebolt.

Short bolts: The number ofsheets in one horizontal course plus two.

Long bolts: The number ofSheets in one course lessone.

Depth of purlin plus 75 mm.

 

Depth of purlin plus 90 mm.

2 At eaves when fillerpieces are not used, atridge when sheets andridge pieces are notsecured by the samebolt. Twice the number of sheetsin one horizontal courseplus one. Depth of purlin plus 75 mm.
3 At intermediate purlinwhen horizontal laps donot occur. The number of sheets in onehorizontal course plus one. Depth of purlin plus 75 mm.

Table : Tests for polycarbonate sheets

Type of span

0.50 mm

TCT steel

(550 MPa )

0.50 mm

TCT steel   (240 MPa )

Roof

 

 

Single span

900 mm

800 mm

Internal span

1800 mm

1400 mm

End span

1200 mm

1000 mm

Overhangs

 

 

Without edge stiffening

150 mm

150 mm

With edge stiffening

300 mm

300 mm

Walls

 

 

Single

1500 mm

1100 mm

Internal span

2000 mm

1400 mm

End span

1800 mm

1200 mm

Overhangs

300 mm

300 mm

 Table : Recommended tests for plastic translucent sheets

Sl. No

Test

Annexure in IS:12866

Value

1

Glass content

A

Not less than 30%

2

Water absorption

B

Not more than 0.3%

3

Hardness

C

Shall not increase by more than 30% of its initial value.

4

Bolt shear

D

Not less than 250N

5

Load deflection test

E

Shall not rupture, minor cracking around the areas of support or loading permitted.

6

Light diffusion

F

Refer table 1000-9

7

Light transmission

G

Refer table 1000-10

Table :  Light diffusion gradient constant

Diffusion Classification

Description

Gradient Constant G

I

Clear

>0.80

II

Moderately diffusing

0.32 – 0.80

III

Heavy diffusing

0.10 – 0.32

IV

Very heavily diffusing

<0.10

 

Diffusion

Classification

Minimum Total Transmission

I

80

II

75

III

70

IV

60

 

Properties

Code

Requirement

Zinc Coating

ASTM A653,

ASTM A755,

IS: 277, IS: 513,

IS: 4246, AS1397,

JISG: 3302,G3312

 

 

 

Primer Service coat

5 microns epoxy/PU on both sides.

Paint coating

Regular modified polyester (optional – silicon modified polyester & PVF2)

Painting thickness (Top)

20 microns (Min).

Painting thickness (Bottom)

7 microns (Min).

Surface Paint reflection

Semi-gloss/matt finish.

Yield strength

300 – 550 MPa.

 

Tests  Requirements
Bend test     4t   (t -nominal thickness of the sheet)   
Pencil hardness test  2H ( H -hardness of pencil )

Table : Physical properties of paint coating for roofing

  g) Recommendations for the use of pre-painted steel sheets for externalapplications are given in table (Ref. IS: 14246).

Table: Recommendations for the use of pre-painted steel sheets for external applications

Sl. No

Material of Coating

Thickness in Micron

Remarks

Top Coat

Epoxy

20-30

For external and internal applications

 

Polyester Polyurethane

20-30

For external and internal applications

 

PVDE

20-30

For external applications. Very good corrosion and weathering resistant

 

Silicon Modified

Polyester

20-30

For external applications. Very good corrosion and weathering resistant.

Back Coat

Alkaloid epoxy or Polyester

7 (Min)

Mainly one coat system or two coat system (Optional with primer).

h)  Manufacturer’s test certificate shall be produced by the Contractor, if the areaof roofing sheets exceeds 150 m2

Aluminium Roofing Sheets

Aluminium roofing sheets are being increasingly adopted in various factories andworkshop sheds,godowns etc. Apart from being corrosion resistant, the aluminiumroofing sheets are lighter in weight and have high scrap value. Aluminium roofingsheets are costlier as far as initial material cost is concerned.

Table : Chemical composition of wrought aluminium and aluminium alloy sheet

Designation

Cu

Mg

Si

Fe

Mn

Zn

Ti and / or other grain refining element

Cr

Al

31000

0.1

0.1

0.6

0.7

0.8-1.5

0.2

0.2

0.2

Remainder

31500

0.2

0.6-1.3

0.4

0.7

1.0-1.5

0.2

0.2

-

Remainder

40800

0.2

0.1

0.6-0.95

0.6-0.95

0.1

0.2

0.2

-

98.0 (min)

51300

0.3

0.2-0.9

0.6

0.9

0.2-0.7

0.4

0.2

0.2

Remainder

 

Designation

Condition

Tensile Strength (MPa)

Elongation on 50 mm gauge length, percent for thickness (t)

Bend test-Radius of bend

Min

Max

0.5 to 0.8 mm

Over 0.8 to 1.3 mm

Over 1.3 to 2.6 mm

Over 2.6 to 6.3 mm

31000

H4

130

180

3

4

5

5

½ t

31500

H4

190

245

3

4

5

5

½ t

40800

H4

125

160

3

4

5

5

½ t

51300

H4

150

200

4

4

5

6

t

e) Designation, characteristics and available forms of alloys used for roofing aregiven in table.

Table : Designation, characteristics and available forms of alloys for roofing

Designation

Characteristics

Available forms

31000

Stronger and harder than 19000* but has good workability, weldability and corrosion resistance

Sheet, plate,extrusion, wire, tubeand forgings.

31500

Strength between alloys 31000 and 52000. It has good formability, weldability and corrosionresistance

Sheet and strip

40800

Strength comparable to alloy 31000 and ductilitycomparable to alloy 19000. This alloy is fine grained and has excellent drawability.

Sheet, strip andplate.

51300

Stronger and harder than alloy 19000. Strengthbetween alloys 31000 and 31500. It has good weldability.

Corrugated sheet,sheet and strip


**Aluminium of grade 19000 is commercially pure, very ductile and excellent in corrosion resistant aluminium..

f) Manufacturer’s test certificate shall be produced by the Contractor, if the areaof roofing sheets exceeds 150 m2

Physical Properties

Average

Measured value

Test standard

 

40±2%

ASTM D 1622-88,

DIN 53420

 

32 to 34

ASTM D 1622-88,

DIN 53420

Thermal conductivity (W/K-m)

0.017-0.023

ASTM C 518-56,

DIN 52612

 

>95

ASTM D 2826,

ISO DP 2246

 

1.7 to 1.9

ASTM D 1621

 

2.8 to 3.0

ASTM D 1621

Flame spread

40 (Max)

ASTM 1692

Self-extinguishing time

40 (Max)

ASTM 1692

Table : Tests standards for FRP sheets

Sl. No

Physical properties

Code

1

Tensile strength

ASTM D 638

2

Tensile modulus

ASTM D 638

3

Flexural strength

ASTM D 790

4

Flexural modulus

ASTM D 790

5

Coefficient of linear thermalexpansion

ASTM D 696

6

Thermal transmittance (UValue)

ASTM D 1363

7

Thermal conductivity(k)

ASTM D 177

8

Izod impact test

ASTM D 256

9

Barcol hardness

ASTM D 2583

10

Limiting oxygen index

ASTM D 2863

11

Smoke density

ASTM D 2843

12

Flammability

UL 94

Table : Requirements for PVC sheets

Sl. No

Physical properties

Code

1

Tensile strength

ASTM D 882 / ASTM D 638

2

Elongation

ASTM D 882 / ASTM D 638

3

Tear Strength

ASTM D 1004

4

Ply adhesion

ASTM D 413

5

Abrasion loss

ASTM D 3389

6

Thickness loss

ASTM D 1593

7

Specific gravity

ASTM D 792

8

Water vapor transmission

ASTM E 96

9

Water absorption

ASTM D 570

10

Dimensional Stability

ASTM D 1204

11

Smoke density

ASTM D 2843

12

Flammability

UL 94

Table : Properties of UPVC Sheets

Property

Test Method

Unit

Requirements

 

Group -1

Group -2

Group -3

Group 4

Class – 1

Class - 2

Class – 1

Class - 2

Class – 1

Class - 2

Tensile

Stress at

yield

ISO

527-3

MPa

≥40

≥40

≥40

≥40

≥40

≥40

≥40

Nominal

strain at

break

ISO

527-3

%

≥20

≥20

≥20

≥20

≥20

≥20

≥20

Tensile

impact

strength

ISO

8256

kJ/m2

-

-

 

≥300

≥300

≥400

≥400

Vicat

Softening

temperature

ISO

306

0C

≥60

≥70

≥60

≥70

≥60

≥70

≥90

Table : Properties of UPVC Sheets

Sl. No

Physical Properties

Code

1

Tensile strength

ASTM D 638

2

Elongation at break

ASTM D 638

3

Density

ASTM D 792

4

Vicat softening temp

ASTM D 1525

5

HDT at 1.8MPa

ASTM D 648

6

Flexural strength

ASTM D 790

7

Oxygen index

ASTM D 2863

8

Chemical resistance

ASTM D 543

9

Water absorption

ASTM D 570

Ceiling with fibre insulating building boards

     Materials

  1. The insulating building boards shall be of approved quality as per IS: 3348 and, unless otherwise specified, shall have square edges.
  2. The dimension shall be subjected to the tolerances given in the table.
  3. Frame of the class of timber and section specified in the description of therelevant item or approved by the Engineer shall be provided. The width of thescantlings provided shall be sufficient to provide a minimum nailing surface of50 mm.

Type of board

Nominal

Thickness

mm

Toleranceon

thickness

mm

 

Length cm

Width cm

Tolerance on

length and

width

Fibreinsulation

board,

ordinary or

flame

retardant type

9

12

18

25

±0.75

±0.75

±1.00

±1.25

365, 300

270, 140

210, 180

150, 120

100, 90

60, 45

and 30

180,

150,

120,

100,

90, 60

45 and

30

For 120 cm

and below ±3

mm and for

above 120

cm ±6 mm

Table : Requirements of cellular concrete

Sl No

Code

Characteristics

Grade A

Grade B

Grade C

1

IS:5688

 

Up to 320

321 to 400

400 to 500

2

IS:5688

 

7.0

12.0

20.0

 

 

-do- type 2

2.5

4.5

8.0

3

IS:5688

Thermal conductivity

(kW/cm 0C)

0.7

0.85

1.0

4

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

Sampling

  1. In a consignment, cellular concrete of the same type and grade andmanufactured approximately in the same period shall be grouped to form a lot.
  2. If it is in the form of blocks, a lot shall be made up of not more than 1000blocks. If the material is in-situ, not more than 10 tonnes of materials shallconstitute a lot.
  3. If the material is transported in trucks and received as such, the material inthe lorry (Or vehicle load) may be conveniently termed as lot.
  4. Each lot shall be tested for all the requirements separately.
  5. If the lot is made up of precast blocks, the number of sample blocks to betested shall be selected at random as per table.

Lot size

Sample size(Block to be sampled) (n)

Permissible No. of defectives (Visual and dimensional requirements) (a)

Up to 100

5

0

101 to 300

8

0

301 to 500

13

0

501 to 1000

20

1

Requirements for fibre glass wool

The requirements of fibre glass wool are given in table.

Sl. No

Properties

Code

Requirements

1

Bulk density

IS: 3144

  12 to 15 kg/m2

2

Recovery after Compression

AnnexureA of IS: 8183

Not less than90% of original thickness.

3

Shot content (Max)

IS: 3144

500 micron (5%), 

250 micron (15%).

4

Moisture contentand absorption

IS: 3144

Not more than 2%.

5

Incombustibility

IS: 3144

Incombustible.

6

Thermal conductivity atmean temperature 50ºC

IS: 3146

0.49 mW/cm C.

7

Sulphur content

IS: 3144

Not more than 0.6%.

Table : Requirements for expanded polystyrene for general use

Sl.No

Characteristics

Requirements at various nominal apparent densities in kg/m3

Code

15

20

25

30

35

1

Thermal conductivity

(K value)

(a) at 0ºC

(b) at 10ºC

 

0.34

0.37

 

0.32

0.35

 

0.30

0.33

 

0.29

0.32

 

0.28

0.30

 

IS: 3346

2

Compressive strength at 10% deformation in kg/cm2 (Min)

0.7

0.9

1.1

1.4

1.7

IS: 4671

Appendix A

3

Cross breaking strength inkg/cm2 (Min)

1.4

1.6

1.8

2.2

2.6

IS: 4671

Appendix B

4

Water vapour permeance in

gm/m2 , 24 hours (Max)

50

40

30

20

15

IS: 4671

Appendix C

5

Thermal stability % (Max)

1

1

1

1

1

IS: 4671

Appendix D

6

Water absorption %

2

1

1

1

1

IS: 4671

Appendix E

Sampling

  1. In a single consignment all the items of the same type, shape and dimensionsbelonging to the same batch of manufacture shall be grouped together toconstitute a lot.
  2. For the purpose of judging conformity to the requirements each lot shall beconsidered separately.
  3. The number of sample items for this purpose shall depend on the size of the lotand shall be in accordance with column 1 and 2 of table .
  4. The sample shall be taken at random from the lot.

 Table : Sampling items

No. of items inthe lot

No. of sample items

Permissible number of defective sample items

Up to 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

  1. All the sample items selected from the lot shall be tested for all requirements of the specifications.
  2. Any item failing in one or more of the requirements shall be regarded asdefective.
  3. Expanded polystyrene can either be fixed with suitable adhesive to the falseceiling board or else it can simply be rolled over the suspended false ceiling.

RELATED CODES :

1.IS: 73- Specification for paving bitumen.

2.IS: 277-Galvanised steel sheets (plain and corrugated).

3.IS: 513-Cold reduced low carbon steel sheets and strips.

4.IS: 651-Terminology glazed stoneware pipes and fittings.

5.IS: 702-Specification for industrial bitumen.

6.IS: 737-Wrought aluminium and aluminium alloy sheet and strip forgeneral engineering purposes.

7.IS: 1199-Methods of sampling and analysis of concrete.

8.IS: 1200-Method of measurements of building and civil engineeringworks:

   (Part -10)Ceiling and lining.

10.IS: 1230-Cast iron rain water pipes and fitting.

     IS: 1254-Corrugated aluminium sheet.

 11.IS: 1367-Technical supply conditions for threaded steel fasteners:

    (Part 13)-Hot dip galvanized coating on threaded fasteners.

12.IS: 2095-Gypsum plaster boards:

    (Part 1)-Plain gypsum plaster boards.

13.IS: 2115-Code of practice for flat roof finish: mud phuska.

14.IS: 2633-Method of testing uniformity of coating on zinc coated articles.

15.IS: 2645-Specification for integral water proofing compounds for cementmortar and concrete

16.IS: 2676-Dimension of wrought aluminium and aluminium alloy sheetand strip.

 17.IS: 3007-Code of practice for laying of asbestos cement sheets:

      (Part 1)-Corrugated sheets.

      (Part 2) -Semi corrugated sheets.

 18.IS: 3087-Particle boards of wood and other lignocellulogic materials(medium density) for general purposes – specifications.

19.IS: 3144-Methods of test for mineral wool thermal insulation materials.

20.IS: 3346-Method of the determination of thermal conductivity of thermalinsulation materials.

21.IS: 3348-Specification for fibre insulation boards.

22.IS: 3384-Specification for bitumen primer for water proofing and dampproofing.

 23.IS: 4671-Expanded polystyrene for thermal insulation purposes.

24.IS: 5382-Specification for rubber sealing rings for gas mains, watermains and sewers.

25.IS: 5688-Methods of test of performed block type and pipe covering typethermal insulations.

26.IS: 6598-Cellular concrete for thermal insulation.

27.IS: 7193-Specification for glass fibre base coal tar pitch and bitumenfelts (Amendment I).

28.IS: 8183-Bonded mineral wool.

29.IS: 10192-Specifications for synthetic resin bonded glass fibre (SRBGF).for electrical purposes

30.IS: 10259-General conditions of delivery and inspection of aluminium andaluminium alloy products.

31.IS: 11551-Glass fibre chopped strand mat for the reinforcement of epoxy,phenolic and polyester resin systems.

32.IS: 12436-Preformed rigid polyurethane (Pur) and polyisocyanurate (Pir)foams for thermal insulation.

33.IS: 12866-Plastic translucent sheet made from thermosetting polyesterresin (Glass fibre reinforced).

34.IS: 13592-Unplasticised polyvinyl chloride (UPVC) pipes for soil and Wastedischarge system for inside and outside building.

35.IS: 14246-Continuously pre painted galvanized steel sheets and coils.

36.IS: 14753-Specifications for polymethyl methacrylate  arylic (PMMA)sheets.

37.IS: 14862-Fibre cement flat sheets-specifications.

38.IS: 14871-Specifications for products in fibre reinforced cement-Longcorrugated or asymmetrical section sheets and fittings forroofing and cladding.

39.IS: 15224-Laying of plastic translucent sheets made from thermosettingpolyester resin (Glass fibre reinforced) alone or in conjunctionwith asbestos cement sheets/steel sheets/aluminium sheets-code of practice.

*****