IS 9862:1981 is the Indian Standard (BIS) for waterproofing of roofs and walls with built-up bituminous felts. This standard provides a code of practice for the waterproofing of roofs, walls, and other building surfaces using a built-up system of bituminous felts. It covers material selection, surface preparation, application techniques for multiple layers, and finishing treatments to protect the waterproofing system. The code aims to ensure a durable and effective barrier against water ingress.
Provides recommendations for the design and installation of built-up bituminous felt systems for waterproofing roofs and walls.
Overview
- Status
- Current
- Usage level
- Frequently Used
- Domain
- Materials Science — Waterproofing and Damp Proofing
- Type
- Code of Practice
- Amendments
- Amendment 1 (Aug 1989); Amendment 2 (Oct 1993)
Also on InfraLens for IS 9862
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
Practical Notes
! Ensure the concrete or masonry surface is completely dry, clean, and free of loose material before applying the primer for proper adhesion.
! Special attention must be paid to detailing at parapet junctions, drain outlets, and expansion joints, as these are critical areas prone to leakage.
! The final protective layer (e.g., stone grit, tiles) is essential to shield the bitumen felt from UV degradation and mechanical damage, significantly extending the life of the waterproofing system.
Frequently referenced clauses
Updates & Amendments2 amendments
Amendment 1 (Aug 1989)
Amendment 2 (Oct 1993)
Consolidated list per BIS. For the text of each amendment, refer to the BIS portal link above.
bitumenbituminous feltprimerwaterproofing
International Equivalents
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International Comparison — Coming Soon
We're adding equivalent international standards for this code.
Key Values6
Quick Reference Values
Minimum side lap for felt75 mm
Minimum end lap for felt100 mm
Bonding bitumen quantity per layer1.2 kg/m²
Primer application rate0.25 to 0.50 litres/m²
Minimum slope for flat roofs for drainage1 in 80 to 1 in 120
Bitumen heating temperatureShould not exceed 200°C
Tables & Referenced Sections
Key Tables
Table 1 - Selection of Waterproofing Treatment for Roofs
Table 2 - Quantities of Materials for Waterproofing Treatment with Bitumen Felts on Roofs per 10 m2
Key Clauses
Clause 4 - Materials
Clause 5 - Preparation of Surface
Clause 6 - Application of Felt on Roofs
Clause 7 - Application of Felt on Vertical and Inclined Surfaces
Clause 8 - Finishing Treatments
Clause 10 - Precautions
Frequently Asked Questions4
What is the minimum recommended overlap for bituminous felt sheets?+
A minimum side lap of 75 mm and a minimum end lap of 100 mm should be maintained (Clause 6.3.2).
How many layers of felt are required for a flat roof?+
It depends on the slope and rainfall conditions. For a nearly flat roof with a slope up to 1 in 80, a five-course treatment is recommended (Table 1).
What is the correct way to apply bonding material?+
Hot bitumen at about 1.2 kg/m² should be applied uniformly just ahead of the felt roll, so the felt is laid on a hot, flowing layer of bitumen (Clause 6.3.1).
Can this waterproofing be applied to vertical surfaces like retaining walls?+
Yes, Clause 7 specifies the method for vertical surfaces, typically involving a two-course treatment with a bitumen primer.
QA/QC Inspection Templates
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QA/QC templates coming soon for this code.