For surfaces subject to foot traffic, which insulation form is specified?

• A. Foam glass
• B. Rigid insulation
• C. Blanket insulation
• D. Mineral wool with jacket

Answer: (B)

The key idea is choosing an insulation form that resists compression and wear when the surface will be walked on. Rigid insulation fits this need because its solid boards keep their thickness and insulating value under foot traffic, providing a stable base for a durable finishing layer like concrete, tile, or epoxy. This durability prevents crushing of the insulation and gaps that would let heat escape. Blanket insulation, being fibrous and flexible, can be crushed by foot traffic, reducing the thermal performance. Mineral wool with jacket is more protective than bare blankets but still relies on a rigid, protected surface for floors to maintain performance under use. Foam glass is rigid as well, but the standard practice for surfaces subjected to foot traffic is to use rigid insulation boards that readily integrate with a protective floor finish.