Can holes be punched directly into the sheets?

No, holes must strictly be drilled, not punched, and should be 2 to 3 mm larger than the bolt diameter to allow for thermal expansion.

Where should fasteners be driven on the sheet?

Fasteners should only be fixed on the crest (crown) of the corrugations, never in the valleys.

What is the standard end lap for roofing sheets?

The standard minimum end lap is 150 mm, which may increase based on the roof slope and exposure.

IS 3007

: 2000

Laying of Asbestos Cement Sheets - Code of Practice, Part 1: Corrugated Sheets

CurrentRareCode of PracticeArchitectural · Cement Matrix Products

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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

Quick Reference Values

minimum end lap150 mm

maximum purlin spacing1.4 m

hole clearance2 to 3 mm larger than fastener diameter

maximum overhang at eaves300 mm

Practical Notes

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.