Glossary of terms relating to bituminous waterproofing and damp-proofing of buildings
1986 Edition

IS 4911 categorizes bituminous felts into several types as follows:

1. Bitumen Felts (Fibre Felts):

• Coated and Sanded: Fibre base coated with oxidized bitumen on one side and fine sand on both surfaces.
• Mineral-Surfaced: Base coated with oxidized bitumen, finished with talc or fine sand on the top surface.
• Reinforced: Bitumen-coated fibre base with embedded organic or inorganic mats for added strength.
• Sanded: Fibre base surfaced on both sides with fine sand, without coating.
• Saturated: Fibre felt without any bituminous coating or surface dressing.
• Self-Finished: Base coated with oxidized bitumen, surfaced with finely divided talc on both sides.

2. Fluxed Pitch Felts:

• Sanded Fluxed Pitch Felt: Coated with fluxed coal tar pitch and surfaced with sand.
• Saturated Fluxed Pitch Felt: Saturated with fluxed pitch without additional coating.

3. Impregnated Felts:

• Flax Felt: Made from flax or jute fibers saturated with fluxed coal tar pitch.
• Hair Felt: Composed of animal hair (sometimes mixed with vegetable fibers) saturated similarly.

4. Asbestos Base Felts:

• Saturated Bitumen Asbestos Felt: No surface dressing or coating.
• Self-Finished Bitumen Asbestos Felt: Bitumen coated and surfaced with finely divided talc.

This classification aids in selecting felts tailored to specific durability and surface finish requirements.

According to IS 4911:1986, waterproofing is defined as a treatment applied to building surfaces to completely prevent the penetration of water, including under hydrostatic pressure. It ensures the structure is protected against water ingress and leakage.

Damp-proofing, in contrast, refers to a treatment aimed at resisting moisture penetration through capillary action or vapor diffusion but is not intended to withstand water under pressure. It primarily reduces dampness in structural elements by limiting moisture migration.

A summarized comparison:

This distinction is critical for choosing appropriate bituminous treatments for different building requirements.

While IS 4911 focuses mainly on terminology, common application practices associated with bituminous materials include:

• Hot Application: Heating bitumen mastic or asphalt and applying it hot, often with tools like wooden floats.
• Cold Application: Utilizing bitumen emulsions or cutbacks applied at ambient temperature.
• Torch-on Application: Heating the underside of modified bitumen felts with a gas torch to bond them to substrates.
• Spraying: Applying bitumen emulsions or cutbacks through spraying equipment for large areas or priming.
• Rolling or Brushing: Using rollers or brushes to spread bitumen primers or coatings.
• Laying Bitumen Felts: Positioning sheets of bitumen felt and bonding them with hot bitumen or adhesives.

These methods ensure effective waterproofing membrane formation and adherence. For detailed procedures, related standards such as IS 1322 and IS 3370 provide comprehensive guidance.

IS 4911 standardizes terminology related to critical bitumen properties used in waterproofing and damp-proofing, including:

• Adhesion: The capability of bitumen in its liquid or semi-solid state to adhere to solid surfaces.
• Alligatoring: A pattern of surface cracking on bituminous layers resembling alligator skin.
• Types of Bitumen: Including straight run, blown or oxidized, cutbacks (rapid, medium, slow curing), steam refined, and emulsions.
• Bitumen Felts: Various types based on their base material and coatings, such as fibre felts, fluxed pitch felts, and asbestos-based felts.
• Bitumen Mastic: A hot-laid compound of bitumen combined with mineral fillers and aggregates.
• Bitumen Primer: Low viscosity binding agents used for surface preparation.
• Other Bituminous Products: Including grouts, built-up roofing systems, and coal tar products.

This terminology ensures a uniform understanding of bitumen's physical forms, modifications, and functional applications within construction waterproofing.

The glossary in IS 4911 serves as a vital tool for accurately specifying roofing materials by:

• Providing Clear Definitions: It clarifies terms like bitumen felts, asphalt mastic, and built-up roofing, ensuring all stakeholders share a common vocabulary.
• Distinguishing Material Types and Properties: Differentiates between various bitumen forms—such as cutbacks, fluxed pitch felts, and emulsions—helping select the correct product based on project demands.
• Explaining Application Concepts: Terms like bonding compound, apron, and cap sheet guide proper installation methods.
• Enhancing Quality Control: Identifies defects such as alligatoring, supporting specification of durability standards.
• Harmonizing Standards: References ASTM and British Standards glossaries to align with international terminology.

For instance, the glossary enables specifying whether a mineral-surfaced or reinforced bitumen felt is appropriate for a given roofing layer, promoting precise communication and performance assurance.