What is the recommended minimum thickness of the polyethylene film for roof waterproofing?

A minimum thickness of 0.10 mm (also known as 400 gauge) is recommended as per Clause 3.1.

What is the minimum overlap required at joints?

The code recommends a minimum lap of 75 mm for both side laps and end laps (Clause 6.1).

Does the polyethylene film need a protective layer?

Yes, a protective finish like cement concrete screed, tiles, or gravel is necessary to protect the film from sunlight, temperature variations, and mechanical damage (Clause 7).

How is the film bonded to the roof surface?

The film is laid over a coat of hot bitumen (not exceeding 200°C) applied to a primed surface (Clause 5.2).

IS 7290

: 1979

Recommendations for use of polyethene film for water-proofing of roofs

CurrentSpecializedGuidelinesBIMArchitectural · Waterproofing and Damp-Proofing

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This standard provides recommendations for using polyethylene film as a waterproofing material for roofs. It covers material specifications, surface preparation, laying procedures, jointing techniques, and the application of a protective surface finish.

Recommendations for use of polyethene film for water-proofing of roofs

Quick Reference Values

Minimum thickness of polyethylene film0.10 mm (400 Gauge)

Minimum side and end lap75 mm

Maximum heating temperature for bitumen200 °C

Quantity of hot bitumen for sticking coat1.2 kg/m²

Practical Notes

This standard has been officially withdrawn by BIS. While the principles are still informative, users should refer to current waterproofing standards and material specifications for modern practices.

The success of the application heavily depends on the quality of surface preparation; the surface must be clean, dry, and smooth to prevent punctures.

Polyethylene film by itself has poor resistance to UV radiation and physical damage, hence the requirement for a protective layer (e.g., screed, tiles) is critical for durability.