Which construction type is known as heavy timber construction with interior framing having minimum dimensions larger than Type 3?

• A. Light timber interior framing
• B. Heavy timber interior framing with minimum dimensions larger than Type 3
• C. Exterior walls noncombustible and interior wood
• D. The interior framing is metal

Answer: (C)

Heavy timber construction is Type IV. The defining feature is interior framing built with large timber members whose dimensions exceed those used in Type III ordinary construction. Exterior walls remain noncombustible, but the big timber members inside resist fire differently than smaller wood members, giving Type IV its characteristic fire resistance. The option describing exterior walls noncombustible and interior wood corresponds to Type III, ordinary construction, not heavy timber. So the scenario of heavy timber interior framing with larger-than-Type-III dimensions points to Type IV.