Type IV construction is commonly known as heavy timber.

• A. True
• B. False
• C. Not applicable
• D. Unspecified

Answer: (A)

Type IV construction uses large, solid timber members and is commonly referred to as heavy timber. The idea behind this classification is the substantial size of the wood members (beams, columns, and decking) that makes the structure more fire-resilient. When exposed to fire, the surface of the timber chars and forms an insulating layer, which slows further burning and helps preserve the integrity of the structural frame for a longer period. This mass and char-protected behavior give Type IV its distinct fire performance compared with other construction types, such as noncombustible (Type II) or wood-frame (Type V). It’s also known in the industry as mill construction, reinforcing that large-dimension timber is the defining feature. So the statement is true.