What is the required slope for a floor in a wet area?

A minimum slope of 1 in 100 should be provided towards drains to ensure no water stagnation (Clause 4.2).

How far up the wall should the waterproofing membrane extend?

The membrane should be taken up the face of the walls to a height of at least 150 mm above the finished floor level (Clause 4.3).

What is the minimum overlap for waterproofing membrane sheets?

A minimum side overlap of 75 mm and an end overlap of 100 mm is required to ensure a continuous waterproof layer (Clause 5.4.1).

What kind of protection is needed over the waterproofing membrane?

A protective layer of cement concrete or mortar screed of at least 20 mm thickness should be laid over the membrane to protect it from damage (Clause 5.5).

IS 9510

: 1980

Code of practice for membrane waterproofing in wet areas of buildings

CurrentSpecializedCode of PracticeBIMMaterials Science · Waterproofing and Damp Proofing

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This code provides guidance on the materials, design considerations, and workmanship for applying membrane waterproofing in building wet areas like bathrooms, kitchens, and balconies. It covers surface preparation, application techniques for membranes, and detailing at critical junctions to prevent water leakage. Note: This standard has been withdrawn, and current practice often relies on manufacturer specifications and the National Building Code (NBC).

Provides recommendations for membrane waterproofing of wet areas like bathrooms, toilets, and kitchens in buildings.

Quick Reference Values

Minimum floor slope for drainage1 in 100

Minimum waterproofing upstand on walls150 mm

Minimum side overlap for membrane sheets75 mm

Minimum end overlap for membrane sheets100 mm

Recommended curing period for substrate concrete28 days

Minimum thickness of protective screed over membrane20 mm

Practical Notes

Extreme care must be taken during surface preparation; the substrate must be clean, dry, and free of sharp projections before laying the membrane.

Junctions between floor and wall, corners, and pipe penetrations are critical areas and require special attention and detailing as specified.

It is highly recommended to conduct a flood test (ponding test) for 24-48 hours to check for leaks before laying the protective screed and final finishes.