Type 4 Construction is best described as?

Type 4 Construction is best described as?

• A. Exterior walls are non-combustible.
• B. Commonly known as wood frame.
• C. Non or Limited Combustible materials. Highest Safety Levels.
• D. Heavy Timber, Large Dimensioned lumber.

Answer: (D)

Type IV construction centers on a heavy timber structural system, using large-dimension lumber for the framing. This defining feature—bold timber members forming the main structure—best fits the description of Heavy Timber, Large Dimensioned lumber. The mass of these timber members gives inherent fire resistance by charring slowly and delaying collapse, rather than relying on noncombustible walls or lightweight wood framing. Other descriptions point to different construction types—for example, noncombustible exterior walls align with Type I/II, and typical wood-frame construction aligns with Type V—so they don’t capture the unique heavy-timber approach that Type IV represents.

Type IV construction centers on a heavy timber structural system, using large-dimension lumber for the framing. This defining feature—bold timber members forming the main structure—best fits the description of Heavy Timber, Large Dimensioned lumber. The mass of these timber members gives inherent fire resistance by charring slowly and delaying collapse, rather than relying on noncombustible walls or lightweight wood framing. Other descriptions point to different construction types—for example, noncombustible exterior walls align with Type I/II, and typical wood-frame construction aligns with Type V—so they don’t capture the unique heavy-timber approach that Type IV represents.