In building materials and finishes (civil engineering), distemper is primarily used as an economical wall coating for which type of surfaces and exposure conditions?

Introduction / Context:
Distemper is a traditional, water-based decorative coating composed of chalk (whiting), binding agents like animal glue or casein, and pigments. It is widely used in building interiors where cost-effectiveness, ease of application, and a matte finish are desired. This question tests where distemper is appropriately specified relative to exposure, substrate, and durability requirements.

Given Data / Assumptions:

• The finish in question is distemper (not acrylic emulsion or cement paint).
• Typical substrates are plastered masonry or gypsum-rendered internal walls.
• Exposure to rain/sun and frequent wetting is considered for exterior/utility spaces.

Concept / Approach:
Distemper provides a breathable, matte coating with moderate washability. It performs best on dry, interior walls away from moisture and abrasive cleaning. It is not recommended for exterior facades, damp-prone walls, or surfaces requiring frequent washing or high adhesion (e.g., woodwork). For exteriors or wet areas, cement paints, acrylic emulsions, or specialized coatings are preferred.

Step-by-Step Solution:
Identify surface type and exposure: interior dry walls are compatible with distemper.Assess durability needs: distemper has limited washability and poor water resistance, so unsuitable for exteriors and wet areas.Evaluate substrate compatibility: woodwork requires enamels or varnishes; distemper does not adhere or wear well on timber.Conclusion: select interior walls not exposed to weather as the correct application zone.

Verification / Alternative check:
Standard specifications list distemper for living rooms, bedrooms, and corridors, while recommending exterior-grade emulsions or cement paint for facades and moisture-prone zones.

Why Other Options Are Wrong:

• External concrete surfaces: need weather-resistant paints; distemper lacks adequate durability.
• Woodwork: requires enamel/PU coatings; distemper is inappropriate.
• Compound walls: subject to moisture and algae; use cement paint or exterior emulsion.
• Countertops/floors: require abrasion-resistant finishes, not wall paints.

Common Pitfalls:
Using distemper in bathrooms/kitchens where splashing and frequent cleaning degrade the film; applying over damp plaster leading to peeling.

Final Answer:
Interior surfaces not exposed to weather