Link points to Internet Archive / others. Not hosted by InfraLens. Details
IS 9918:1981 is the Indian Standard (BIS) for in-situ waterproofing and damp-proofing treatments with glass fibre tissue-reinforced bitumen. 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
Overview
Status
Current
Usage level
Specialized
Domain
Materials Science — Waterproofing and Damp-Proofing
! 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.
BS 8217:2005BSI - British Standards Institution, UK
HighCurrent
Reinforced bitumen membranes for roofing. Code of practice
Directly corresponds to the roofing application of built-up, reinforced bitumen membranes using pour-and-roll techniques.
ASTM D6622 - 15(2021)ASTM International, USA
HighCurrent
Standard Guide for Application of Fully Adhered Hot-Applied Reinforced Waterproofing Systems
Provides guidance for the application of hot-applied, reinforced systems, which aligns with the in-situ method of IS 9918.
DIN 18531-1:2017DIN - Deutsches Institut für Normung, Germany
MediumCurrent
Waterproofing of roofs - Part 1: Non-used and used roofs - Requirements and principles
Covers the overall design and principles for roof waterproofing, including bitumen-based systems, but is more modern and comprehensive.
BS 8102:2022BSI - British Standards Institution, UK
MediumCurrent
Code of practice for protection of below ground structures against water from the ground
Corresponds to the damp-proofing and below-ground aspects of IS 9918, focusing on design philosophy rather than specific material application.
Key Differences
≠IS 9918 is based on straight-run industrial bitumen (as per IS 1580), whereas modern international standards predominantly specify or recommend polymer-modified bitumen (SBS/APP), which offer significantly better elasticity, temperature stability, and durability.
≠Modern international standards (e.g., referenced in BS 8217) extensively cover torch-on application of pre-fabricated membranes. IS 9918 focuses exclusively on the older, in-situ hot mopping 'pour-and-roll' technique.
≠International codes like BS 8102 and DIN 18531 incorporate a risk-based design approach and system classifications (e.g., Type A, B, C waterproofing in BS 8102). IS 9918 is a prescriptive code, detailing a single method without broader design philosophy.
≠IS 9918 relies on a relatively light glass fibre tissue (typically 50 g/m² per IS 7193). International standards for reinforced membranes often utilize heavier, more robust glass or polyester reinforcements, or composite reinforcements for higher mechanical strength.
Key Similarities
≈The fundamental concept of creating a multi-layer, built-up waterproofing system using bitumen as the binder and a fibre reinforcement is common to both IS 9918 and international standards like BS 8217 for BUR systems.
≈All standards emphasize the critical need for proper substrate preparation, including ensuring the surface is clean, dry, smooth, and correctly primed to achieve adequate adhesion of the waterproofing system.
≈The principle of overlapping successive layers of reinforcement is a core requirement in both IS 9918 and its international counterparts to ensure a continuous, monolithic membrane and prevent water ingress at joints.
≈Both the Indian and international standards mandate the use of a protective finish (e.g., mineral granules, gravel, tiles, or a screed) over the membrane to shield it from UV radiation and mechanical damage.
Parameter Comparison
Parameter
IS Value
International
Source
Bitumen Application Temperature
180°C to 200°C
Application within ±14°C of the Equiviscous Temperature (EVT), typically 205-235°C for roofing asphalt.
ASTM D6622 (referencing material specs like ASTM D312)
Minimum Side Lap Width
75 mm
75 mm
BS 8217:2005
Minimum End Lap Width
100 mm
100 mm
BS 8217:2005
Bitumen Primer Application Rate
0.3 to 0.4 litre/m²
Qualitative guidance: 'apply sparingly'. Manufacturer's specs typically range from 0.2 to 0.5 litre/m².
BS 8217:2005
Inter-ply Bitumen Application Rate
1.2 kg/m² per coat
Nominal 1.4 kg/m² for bonding coats in pour-and-roll applications.
BS 8217:2005
Glass Fibre Reinforcement Mass (Base Mat)
50 g/m² (as per IS 7193)
44 g/m² (Type IV) to 83 g/m² (Type VI)
ASTM D2178 (Standard Specification for Asphalt Glass Felt)
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).