Building materials — bituminous felts in building construction Bituminous felts (bituminous membranes) are commonly specified for which application on buildings?

Introduction / Context:
Bituminous felts (also called bituminous membranes or roofing felts) are factory-made sheets impregnated or coated with bitumen. They are widely used in civil engineering works to resist water ingress. Knowing their correct application helps designers and site engineers select the right material for damp-proofing and waterproofing.

Given Data / Assumptions:

• Bituminous felt is flexible, water-resistant, and usually laid in one or more plies with hot or cold bitumen bonding.
• Applications include damp-proof courses (D.P.C.) in walls and floors, and membrane waterproofing on terraces and basements.
• The question asks for the most appropriate/common building application.

Concept / Approach:
A D.P.C. is a barrier against capillary rise of moisture from substructure into superstructure. Bituminous felts provide an effective impermeable barrier when properly lapped and bonded. While felts may be used on some roof build-ups, they are not intended just to “cover” A.C. sheets for appearance, and they are not typically the primary outermost layer on steep sloping roofs without a full roofing system.

Step-by-Step Solution:
Identify the property: bituminous felts are waterproof and flexible.Map property to use: ideal for D.P.C. and membrane waterproofing (horizontal and vertical).Evaluate distractors: aesthetic covering of A.C. sheets is not a standard specification; sloping roofs typically use tiles/sheets/shingles, with felts as underlays only.Hence, the correct, textbook use is D.P.C. and waterproofing layers.

Verification / Alternative check:
Standard building codes and specifications list bituminous felt as an approved D.P.C. material alongside PVC membranes and polymer-modified bituminous sheets.

Why Other Options Are Wrong:
Covering A.C. sheets: not a normal or recommended application; does not address jointing/fastener penetrations properly.

Covering sloping roofs: felts alone are not used as the outer weathering surface on steep roofs; they may be an underlayment only.

None of these and temporary shuttering: incorrect; felts are not shuttering materials.

Common Pitfalls:
Using felts without proper laps/primers; laying on dusty or damp substrates; inadequate upturns/flashings at edges; ignoring UV protection where exposed.

Final Answer:
Providing a damp-proof course (D.P.C.) and waterproofing layers