What are the main types of felts specified in IS 7193?

Type 1 (Self-finished bitumen surface) and Type 2 (Surfaced with mineral granules) are the two main types, each with Grade 1 and Grade 2 (Clause 3.2).

What is the minimum breaking strength for the most common type of felt?

For Type 2, Grade 1 felt, the minimum breaking strength is 350 N/50mm width in the longitudinal direction (Table 1).

What is the pliability test requirement?

The felt strip shall not show any cracks when bent around a specified mandrel at a temperature of 0 ± 1°C (Table 1).

What are the standard roll dimensions?

The standard width is 1 meter, and standard lengths are 10 or 20 meters (Clause 6.1).

IS 7193

: 1994

glass fibre base bitumen felts

CurrentSpecializedSpecificationBIMMaterials Science · Waterproofing and Damp-Proofing

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This standard specifies the requirements for glass fibre base bitumen felts used for waterproofing and damp-proofing. It covers material composition, manufacturing, dimensions, physical properties such as breaking strength and water absorption, and methods of sampling and testing for different types and grades.

glass fibre base bitumen felts

Quick Reference Values

Standard Roll Width1 m

Standard Roll Length10 m or 20 m

Breaking Strength (min, Type 2, Grade 1)350 N / 50 mm width

Pliability Test Temperature0 °C (no cracking)

Heat Resistance Test Temperature85 °C (no flow or blistering)

Water Absorption (max)1.0 % by mass

Practical Notes

The standard covers two types: Type 1 (self-finished) and Type 2 (mineral granule surfaced). Choose Type 2 for surfaces exposed to UV and light foot traffic.

Ensure proper surface preparation, including cleaning and priming with a suitable bitumen primer as per IS 1580, before applying the felt.

Lapping is critical for performance. Adhere to specified side laps (typically 75 mm) and end laps (100 mm) using hot bitumen or cold adhesive.