Which building type will present a greater potential for collapse?

Which building type will present a greater potential for collapse?

• A. Heavy-timber construction, Type IV
• B. Fire resistive construction, Type I
• C. Lightweight wood-frame construction, Type V
• D. Masonry construction, Type III

Answer: (C)

The key idea is how fire affects the stability of different building types. Lightweight wood-frame construction presents the greatest collapse potential in a fire because its framing is highly combustible, has limited redundancy, and relies on many slender wooden members that burn quickly. When a fire attacks a lightweight structure, floor and wall joists, studs, and connections can fail in rapid sequence, disrupting load paths and leading to a sudden collapse as the fire consumes the main structural members and any hidden spaces allow heat to spread unchecked. In contrast, heavy-timber construction uses large timber members that char and burn more slowly, creating a protective heat layer and maintaining structural capacity longer; fire-resistive construction employs noncombustible materials designed to resist heat and preserve integrity for rated periods; masonry construction involves heavy, noncombustible walls that provide substantial mass and resistance, though they can fail if the fire is prolonged or affects supporting members. This combination makes lightweight wood-frame the most prone to collapse under fire.

The key idea is how fire affects the stability of different building types. Lightweight wood-frame construction presents the greatest collapse potential in a fire because its framing is highly combustible, has limited redundancy, and relies on many slender wooden members that burn quickly. When a fire attacks a lightweight structure, floor and wall joists, studs, and connections can fail in rapid sequence, disrupting load paths and leading to a sudden collapse as the fire consumes the main structural members and any hidden spaces allow heat to spread unchecked.

In contrast, heavy-timber construction uses large timber members that char and burn more slowly, creating a protective heat layer and maintaining structural capacity longer; fire-resistive construction employs noncombustible materials designed to resist heat and preserve integrity for rated periods; masonry construction involves heavy, noncombustible walls that provide substantial mass and resistance, though they can fail if the fire is prolonged or affects supporting members. This combination makes lightweight wood-frame the most prone to collapse under fire.