What is the correct bitumen to use for roof waterproofing under this code?

Industrial Bitumen of grade 85/25 or 90/15, conforming to IS 702, is recommended (Clause 4.1).

How much should the glass fibre tissue layers overlap?

A minimum of 75 mm for side laps and 100 mm for end laps must be maintained for all layers (Clause 6.2.3).

Is a primer always necessary for this treatment?

Yes, a coat of bituminous primer conforming to IS 3384 must be applied to the prepared surface before the first coat of hot bitumen (Clause 6.2.1).

What is the recommended finishing treatment for a roof?

A final coat of hot bitumen is applied, and while it is still hot, coarse sand or grit is spread over it. Alternatively, covering with precast concrete tiles on a sand-cement mortar bed is also an option (Clause 7.2).

IS 9918

: 1981

Code of practice for in-situ waterproofing and damp-proofing treatments with glass fibre tissue-reinforced bitumen

CurrentSpecializedCode of PracticeMaterials Science · Waterproofing and Damp-Proofing

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This code of practice outlines the materials, surface preparation, and application procedure for in-situ waterproofing and damp-proofing using hot-applied bitumen reinforced with glass fibre tissue. It provides specifications for creating a monolithic membrane on various building surfaces like roofs, basements, and walls.

Code of practice for in-situ waterproofing and damp-proofing treatments with glass fibre tissue-reinforced bitumen

Quick Reference Values

Recommended bitumen grade for waterproofingIndustrial Bitumen 85/25 or 90/15

Minimum weight of glass fibre tissue40 g/m²

Bitumen quantity for first coat (roofs)1.2 kg/m²

Bitumen quantity for subsequent coats (roofs)1.0 kg/m²

Minimum side lap for glass fibre tissue75 mm

Minimum end lap for glass fibre tissue100 mm

Primer consumption rate0.25 to 0.50 litre/m²

Practical Notes

Surface preparation is critical; the surface must be completely clean, dry, and free of any loose material before applying the primer.

The temperature of the bitumen must be carefully controlled during heating and application to prevent degradation of its properties and to avoid fire hazards. A thermometer is essential.

Ensure the glass fibre tissue is pressed firmly into the hot bitumen to eliminate air pockets and ensure a fully bonded, monolithic membrane.