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IS 3384:1986 is the Indian Standard (BIS) for laying bitumen felt for roofing. This standard outlines the code of practice for preparing roof surfaces and laying bitumen felts for waterproofing. It specifies the methods for various multi-course treatments (e.g., four-course, six-course) based on climatic conditions, roof slopes, and base materials to ensure effective and durable moisture protection.
Provides recommendations for proper methods of laying bitumen felt for waterproofing of roofs.
! Blistering is a common defect; to prevent it, ensure the roof surface is bone-dry and free from dust before applying the bitumen primer.
! Always unroll the felt completely and let it rest flat before laying to relieve internal stresses and prevent subsequent wrinkling.
! Special attention must be given to critical junctions like rainwater outlets, parapet walls, and expansion joints, as these are primary points of waterproofing failure.
BS 8217:2005BSI (British Standards Institution), UK
HighCurrent
Reinforced bitumen membranes for roofing. Code of practice
Provides guidance on the design, material selection, and application of reinforced bitumen roofing systems.
DIN 18531-3:2017DIN (Deutsches Institut für Normung), Germany
HighCurrent
Roof waterproofing - Part 3: Design and execution of waterproofing for roofs not used for foot traffic
Specifies requirements for the planning, design, and execution of waterproofing, including bituminous membranes.
ASTM D6622-07(2015)ASTM International, USA
MediumCurrent
Standard Guide for Application of Fully Adhered Hot-Applied Reinforced Waterproofing Systems
Covers the installation procedures for hot-applied reinforced bituminous systems, a subset of methods in IS 3384.
AS 4654.2-2012Standards Australia, Australia
MediumCurrent
Waterproofing membranes for external above-ground use, Part 2: Design and installation
Provides requirements for designing and installing various waterproofing membranes, including bituminous types.
Key Differences
≠IS 3384 focuses on traditional materials like hessian or fibre-based bitumen felts, whereas modern standards (e.g., BS 8217) extensively cover polymer-modified bitumen (APP, SBS) and advanced reinforcements (polyester, glass fibre).
≠The Indian standard primarily details the hot-mopped 'pour and roll' application technique. International equivalents give equal or greater emphasis to modern methods like torch-on application and self-adhered membranes.
≠International standards like DIN 18531 and BS 8217 adopt a 'total system' approach, including detailed guidance on vapour control layers, insulation, and deck compatibility, which is less pronounced in IS 3384.
≠While IS 3384 provides basic detailing for upstands and outlets, standards like BS 8217 offer significantly more comprehensive and illustrated guidance for complex roof penetrations, terminations, and movement joints.
Key Similarities
≈All standards universally mandate that the roof substrate must be clean, dry, smooth, and free of contaminants before the application of the membrane.
≈The fundamental principle of lapping joints (side and end laps) to ensure a watertight, weather-shedding seal is a core requirement in both IS 3384 and its international counterparts.
≈The requirement to stagger all joints between successive layers of felt to prevent a continuous vertical path for water ingress is a common practice specified across all codes.
≈All standards emphasize the need for adequate roof falls (slope/gradient) to ensure positive drainage and prevent the ponding of water on the finished roof surface.
≈Carrying the waterproofing membrane up vertical abutments (parapets, walls) to a minimum specified height (typically 150 mm) is a standard detailing practice in all referenced codes.
Parameter Comparison
Parameter
IS Value
International
Source
Minimum Roof Fall / Slope
1 in 60 (approx. 1.67%)
Design fall of 1 in 40 (2.5%); finished fall should not be less than 1 in 80 (1.25%)
BS 8217:2005
Minimum End Lap
100 mm
100 mm (for hot-applied or torch-on)
BS 8217:2005
Minimum Side Lap
75 mm
75 mm (for hot-applied or torch-on)
BS 8217:2005
Minimum Upstand Height at Abutments
150 mm
150 mm above finished roof level
BS 8217:2005
Staggering of Side Laps
Joints in successive layers shall be staggered (e.g., by half width of felt).
Side laps of successive layers should be offset by a minimum of 300 mm.
BS 8217:2005
Bonding Method
Primarily hot-mopped bitumen bonding.
Includes hot-mopped, torch-on, cold-applied adhesive, and self-adhesive methods.
BS 8217:2005
Hot Bitumen Application Temp (Typical)
Approx. 180-200°C (for Grade 85/25, per IS 702)
191 to 218°C (for Type III/IV asphalt)
ASTM D6622-07
⚠ Verify details from original standards before use
Key Values5
Quick Reference Values
Minimum side (longitudinal) overlap75 mm
Minimum end (transverse) overlap100 mm
Minimum height for tucking felt into parapet wall groove150 mm
Recommended slope for flat roof drainage1 in 40 to 1 in 60
Groove depth in parapet for tucking feltMinimum 65 mm deep by 50 mm wide
Tables & Referenced Sections
Key Tables
Table 1 - Details of Treatments with Hessian-Base or Fibre-Base Bitumen Felts
Table 2 - Details of Treatments with Glass Fibre Base Bitumen Felts
Key Clauses
Clause 4 - Preparation of Surface
Clause 5 - Types of Treatment (Four-course, Six-course, etc.)
Clause 6 - Laying Procedure
Clause 7 - Details at Parapets, Gutters and Rain-Water Pipes
What is the minimum overlap required when laying bitumen felts?+
A minimum overlap of 75 mm is required for longitudinal (side) joints and 100 mm for transverse (end) joints.
How should waterproofing be detailed at a parapet wall?+
The felt must be taken up the parapet wall to a minimum height of 150 mm and securely tucked into a chase/groove cut into the masonry.
When is a six-course treatment preferred over a four-course treatment?+
A six-course treatment, which includes an additional layer of felt and bitumen, is recommended for severe climatic conditions or areas with heavy rainfall.