Which layer is used over joists to form a working platform for finishing floor coverings?

Which layer is used over joists to form a working platform for finishing floor coverings?

• A. Siding
• B. Insulation
• C. Decking
• D. Subflooring

Answer: (D)

When building floors, the layer placed over the joists to create a solid, flat base for finishing floor coverings is the subflooring. Subflooring, usually plywood or OSB, is fastened directly to the joists to form a continuous plane that resists deflection, distributes loads, and prevents squeaks or bounce. It provides the proper nailing surface for the finish floor and helps ensure that carpets, hardwood, tile, or other coverings go down reliably and wear evenly over time. Siding is used on exterior walls, insulation sits between framing members to reduce heat flow, and decking generally refers to a platform surface for exterior spaces or, in some contexts, the structural layer beneath an exterior finish—neither of which serves as the standard base for interior finish floors.

When building floors, the layer placed over the joists to create a solid, flat base for finishing floor coverings is the subflooring. Subflooring, usually plywood or OSB, is fastened directly to the joists to form a continuous plane that resists deflection, distributes loads, and prevents squeaks or bounce. It provides the proper nailing surface for the finish floor and helps ensure that carpets, hardwood, tile, or other coverings go down reliably and wear evenly over time.

Siding is used on exterior walls, insulation sits between framing members to reduce heat flow, and decking generally refers to a platform surface for exterior spaces or, in some contexts, the structural layer beneath an exterior finish—neither of which serves as the standard base for interior finish floors.