Type IV Construction is characterized by what?

• A. Wood frame (Residential)
• B. Noncombustible (Industrial)
• C. Concrete and steel hybrid
• D. Heavy Timber (Barn)

Answer: (D)

Type IV construction is defined by heavy timber framing. The key feature is the use of large-dimension timber members—massive beams and columns—for the structural frame, often with masonry or concrete exterior walls. The substantial size of the timbers allows them to char slowly and maintain structural integrity during a fire, giving the building greater fire resistance without relying on steel or concrete for the frame. Interiors are often left with exposed timber, emphasizing the heavy timber aesthetics.

This is different from wood-frame (residential) construction, which uses smaller wood members and more combustible interior finish; or from noncombustible types that rely on steel or concrete for the frame. Concrete-and-steel hybrids aren’t a standard Type IV arrangement, but heavy timber framing is the hallmark of this construction type.