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IS 4365:1967 is the Indian Standard (BIS) for the application of bitumen mastic for waterproofing of roofs. This code specifies the procedures for preparing surfaces and applying bitumen mastic for waterproofing roofs. It details heating limits, laying techniques, and the treatment of construction joints to ensure a durable and watertight roofing layer.
Code of practice for the application of bitumen mastic for waterproofing of roofs
Consolidated list per BIS. For the text of each amendment, refer to the BIS portal link above.
bitumen masticwaterproofingprimermastic asphalt
International Equivalents
Similar International Standards
BS 8218:2018BSI - British Standards Institution, UK
HighCurrent
Code of practice for application of mastic asphalt
Directly equivalent code of practice for the application of mastic asphalt (bitumen mastic) for waterproofing.
DIN 18531-1:2017DIN - Deutsches Institut für Normung, Germany
HighCurrent
Waterproofing for roofs and for balconies, loggias and walkways - Part 1: Requirements, design and execution principles for non-utilized and utilized roofs
Covers principles for roof waterproofing, including systems using mastic asphalt ('Gussasphalt').
BS EN 12970:2007CEN - European Committee for Standardization (adopted by BSI)
MediumCurrent
Mastic asphalt for waterproofing - Definitions, requirements and test methods
Specifies the material itself (mastic asphalt), which is referenced by application codes like BS 8218.
Key Differences
≠IS 4365 is a 1967 standard with dated technology, while modern equivalents like BS 8218 incorporate polymer-modified mastic asphalt (PMA) for enhanced flexibility, durability, and temperature stability.
≠The Indian standard specifies a basic hessian-based felt underlay, whereas international standards mandate more advanced separation layers (e.g., glass-fibre or polyester-based membranes) to accommodate thermal movement and prevent blistering.
≠Material testing differs significantly. IS 4365 (referencing IS 1195) uses a hardness number test at 25°C, while EN 12970 defines various grades based on indentation depth at higher temperatures (e.g., 40°C), which better reflects in-service conditions.
≠IS 4365 provides a single nominal thickness (25 mm) for roofing, while standards like BS 8218 provide a range of thicknesses and specifications tailored to different roof types, traffic levels, and whether the membrane is protected or exposed.
Key Similarities
≈The core principle of applying a hot, monolithic, voidless layer of bitumen mastic/asphalt with a wooden float to form an impermeable barrier is fundamental to both the IS code and its international counterparts.
≈All standards emphasize the critical importance of a clean, dry, and stable substrate, and the use of a suitable bitumen primer to ensure proper adhesion of the waterproofing layer.
≈The application methodology of laying the mastic in two separate coats is a common requirement to ensure a continuous layer and minimize the risk of defects like pinholes.
≈The practice of applying a surface finish (e.g., mineral grit, solar reflective paint, or paving tiles) to protect the black mastic asphalt from UV degradation and mechanical damage is a shared concept.
Parameter Comparison
Parameter
IS Value
International
Source
Nominal Application Thickness (Roofing)
Not less than 25 mm, laid in two coats.
20 mm, laid in two 10 mm coats for standard roofs.
BS 8218:2018
Application Temperature
175°C to 205°C
Typically 200°C to 230°C (depending on grade and manufacturer guidance).
BS 8218:2018
Material Hardness Test
Hardness number of 20-60 at 25°C (per IS 1195).
Defined by indentation depth at 40°C, e.g., 4.0-6.0 mm for a common roofing grade.
BS EN 12970:2007
Underlay/Separating Layer
Hessian base self-finished bitumen felt.
Glass fibre tissue or polyester-based isolating membrane.
BS 8218:2018
Binder Type
Industrial grade bitumen (e.g., 85/25) as per IS 702.
Allows for standard bitumen and specifies Polymer Modified Bitumen (e.g., SBS modified) for enhanced performance.
BS EN 12970:2007
Maximum Gradient for Application
Not explicitly stated, but implies use on flat roofs.
Generally suitable for flat roofs and slopes up to 10° (1:5.7). Special grades required for steeper slopes.
BS 8218:2018
⚠ Verify details from original standards before use
Key Values4
Quick Reference Values
Heating temperature of bitumen mastic180°C to 200°C
Minimum slope of roof base for drainage1 in 100
Minimum overlap for construction joints75 mm
Typical application thickness10 mm to 20 mm (often in two layers)