Buildings constructed with heavy timber fall under which classification type?

Buildings constructed with heavy timber are classified as Type IV under the building classification system. This classification includes structures that utilize large wood beams and columns, which offer greater fire resistance compared to lighter wood frame construction. Type IV buildings are specifically designed to take advantage of the inherent fire-resistance qualities of heavy timber, as the larger dimensions of the wood elements allow them to char on the outside while maintaining structural integrity for an extended period during a fire event.

This classification aims to promote the use of heavy timber construction in a safe and effective manner, allowing for larger spaces and creative designs, while ensuring adherence to fire safety codes. Type I and Type II classifications generally pertain to non-combustible materials and lighter wood frame structures, respectively, while Type III often involves exterior walls of non-combustible materials but allows for wood framing. None of these classifications provide the same context for heavy timber as Type IV does.