In ordinary wood-frame construction, the wood floors are typically supported by what?

• A. Tied into bearing walls
• B. Secured by pier and beam constriction
• C. Typically supported by joists
• D. Fire rated and protected

Answer: (C)

In ordinary wood-frame construction, the floor is carried by horizontal members called floor joists. These joists run between supports—such as bearing walls or beams—and support the subfloor on their top edges. The load from the floor, occupants, and furniture is transferred down through the joists to the walls or beams below. Platform framing typically uses this joist system to form each floor, so floor joists are the primary structural elements carrying the floor load.

Tied into bearing walls is happening, but the key and most direct structural element doing the carrying is the joist system. Pier-and-beam foundations describe a different setup, and fire-rated protections relate to specific assemblies rather than the basic support method.