Which term refers to the plywood or dimensional lumber that covers the walls under the siding?

Which term refers to the plywood or dimensional lumber that covers the walls under the siding?

• A. Siding
• B. Sheathing
• C. Framing
• D. Lath

Answer: (B)

That backing layer is called sheathing—the plywood or dimensional lumber installed over the wall framing to provide a solid surface for attaching the siding. It adds rigidity to the wall and serves as a base for the exterior finish, often working with a moisture barrier and insulation. Siding is the exterior finish itself, not the layer beneath. Framing is the structural skeleton of the wall (the studs and plates). Lath is a base used with plaster or stucco, not the typical backing for modern siding.

That backing layer is called sheathing—the plywood or dimensional lumber installed over the wall framing to provide a solid surface for attaching the siding. It adds rigidity to the wall and serves as a base for the exterior finish, often working with a moisture barrier and insulation. Siding is the exterior finish itself, not the layer beneath. Framing is the structural skeleton of the wall (the studs and plates). Lath is a base used with plaster or stucco, not the typical backing for modern siding.