In Type 4 construction, exterior walls are described as what?

• A. Wooden
• B. Steel
• C. Noncombustible or limited combustible
• D. Concrete

Answer: (C)

In Type IV construction the emphasis is on a heavy timber frame, but the exterior walls must still provide strong fire resistance. That’s why exterior walls are described as noncombustible or limited combustible. Using noncombustible or limited combustible materials for the walls helps prevent rapid flame spread and protects the timber frame, even though the main structural members are wood. Calling the walls wooden would misrepresent the fire-resistance requirement, and while concrete is noncombustible, the correct, general description used in code contexts is noncombustible or limited combustible.