What is the minimum recommended pitch for a GS sheet roof?

For sheet lengths up to 5m, the minimum pitch is 1 in 5. For lengths over 5m, it is 1 in 3 (Table 1).

What is the minimum end lap for corrugated sheets?

The minimum recommended end lap is 150 mm (Table 2).

How many fasteners are required per sheet?

Generally, a minimum of 3 fasteners per sheet at each purlin are recommended, with additional fasteners in high wind zones (Clause 7.2).

What is the minimum side lap for corrugated sheets?

A minimum side lap of two corrugations is recommended (Clause 6.3.1).

IS 12093

: 1987

Code of practice for laying and fixing sloped roof coverings using plain and corrugated galvanized steel sheets

CurrentFrequently UsedCode of PracticeBIMArchitectural · Building Construction Practices incl. Painting, Varnishing

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This standard outlines the code of practice for laying and fixing sloped roof coverings using plain and corrugated galvanized steel sheets. It provides guidance on materials, supporting framework, laying procedures, fixing methods, and weatherproofing details like ridges and gutters. The primary objective is to ensure the roof is structurally sound, weather-resistant, and durable.

Code of practice for laying and fixing sloped roof coverings using plain and corrugated galvanized steel sheets

Quick Reference Values

Minimum roof pitch (up to 5m sheet length)1 in 5 (11.3°)

Minimum roof pitch (over 5m sheet length)1 in 3 (18.4°)

Minimum end lap150 mm

Minimum side lap (corrugated sheets)2 corrugations

Maximum purlin spacing (for 0.63 mm thick sheet)1.6 m

Maximum purlin spacing (for 1.25 mm thick sheet)2.5 m

Minimum projection at eaves150 mm

Practical Notes

Laying of sheets should commence from the leeward side of the roof (opposite to prevailing wind direction) and from the eaves towards the ridge to ensure proper overlaps prevent wind and water ingress.

Using incorrect fasteners or spacing is a major cause of roof failure in high winds. Ensure hook bolts, J-bolts, or self-tapping screws of the specified size and material are used at the recommended spacing.

Pay close attention to waterproofing details at laps, ridges, hips, valleys, and any roof penetrations using appropriate sealants and flashings as per the code.