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IS 3007:2000 (Part 1) is the Indian Standard (BIS) for laying of asbestos cement sheets - code of practice, part 1: corrugated sheets. This code covers the essential guidelines for laying, fixing, and maintaining corrugated asbestos cement sheets for roofing and cladding. It details purlin spacing, overlap requirements, proper fastening techniques, and mitring to ensure weather-tightness and structural stability.
Laying of Asbestos Cement Sheets - Code of Practice, Part 1: Corrugated Sheets
! Holes must never be punched in asbestos cement sheets; they must always be drilled to prevent micro-cracking.
! Fasteners must always be installed on the crown (crest) of the corrugation with bitumen washers to prevent water leakage.
! Mitring is mandatory at the corners where four sheets overlap to prevent excessive thickness buildup and gaps.
! Due to health hazards associated with asbestos, adequate personal protective equipment (PPE) like masks must be used to avoid inhaling asbestos dust during cutting and drilling.
BS 5247-14:1975British Standards Institution (BSI), UK
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Code of practice for sheet roof and wall coverings. Corrugated asbestos-cement
Provides a comprehensive code of practice for the installation of corrugated asbestos-cement roofing in the UK.
ISO 7337:1984International Organization for Standardization (ISO), International
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Asbestos-cement products — Code of practice for roofing
Specifies international guidelines for the design and installation of asbestos-cement roofing systems.
SABS 0134:1972South African Bureau of Standards (SABS), South Africa
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Code of practice for the use of asbestos-cement corrugated sheeting
Covers the materials, design considerations, and erection of corrugated asbestos-cement sheeting for roofs and walls.
Key Differences
≠IS 3007:2000 references Indian-specific standards for wind load calculation (IS 875 Part 3), whereas international counterparts like BS 5247 referenced British wind load codes (e.g., CP3), leading to different design pressures.
≠The Indian standard remained current until its 2000 revision, long after many Western countries had begun phasing out asbestos. Consequently, older international standards like BS 5247:1975 contain safety guidance on asbestos handling that is now considered grossly inadequate, while IS 3007 reflects a slightly more modern (though still outdated by today's standards) awareness.
≠IS 3007 specifies material compliance by referencing Indian product standards (e.g., IS 459 for AC sheets), while the BS and ISO standards reference their respective British and International product specification standards.
≠While all standards specify end laps based on roof slope, IS 3007 provides a simpler table, whereas standards like ISO 7337 may provide more nuanced recommendations based on combined factors of rainfall intensity and wind conditions prevalent in different climatic zones.
Key Similarities
≈All standards mandate the fundamental principle of laying sheets starting from the eaves and working towards the ridge, and against the direction of the prevailing wind and rain to protect side laps.
≈A universal requirement across IS 3007 and its international equivalents is the use of oversized holes (clearance holes) for fixings to allow for thermal expansion and contraction of the sheets without causing stress fractures.
≈All codes specify the use of appropriate bolts (J-bolts, L-hooks) with sealing washers (e.g., bitumen, lead, or plastic) to prevent water ingress at fixing points.
≈The concept of minimum end laps and side laps to ensure water tightness is a core, technically similar principle in all the standards, with specified lap dimensions being very close.
Parameter Comparison
Parameter
IS Value
International
Source
Maximum Purlin Spacing (6mm Sheet, Roofing)
1.40 m
1.375 m
BS 5247-14:1975
Minimum End Lap (General)
150 mm
150 mm (for pitches ≥ 10°)
ISO 7337:1984
Minimum Side Lap
Half-corrugation
One corrugation
ISO 7337:1984
Fixing Hole Diameter Clearance
2 mm larger than fixing bolt diameter
2-3 mm larger than fixing shank diameter
BS 5247-14:1975
Maximum Projection at Eaves (Unsupported)
Not exceeding 300 mm
Not exceeding 300 mm
BS 5247-14:1975
Recommended Minimum Roof Pitch
Generally ≥ 10°, with provisions down to 5°
5.7° (10% gradient), with steeper pitches recommended
ISO 7337:1984
⚠ Verify details from original standards before use
Key Values4
Quick Reference Values
minimum end lap150 mm
maximum purlin spacing1.4 m
hole clearance2 to 3 mm larger than fastener diameter