What type of construction is associated with structures that contain heavy timber?

Structures that contain heavy timber are classified as Type IV construction, which is specifically designed to take advantage of the fire-resistance properties of heavy timber. In this construction type, the major structural components, such as beams and columns, are substantial enough to resist fire for a longer duration than lighter materials, which also provides significant structural integrity.

Heavy timber construction often uses large wood members, typically greater than 5 inches in thickness, which can withstand fire exposure better than smaller wood components. This is essential because it slows down the rate at which the material will burn through, thus providing a safer environment during a fire. Moreover, Type IV construction is often required for buildings of certain sizes and heights due to legal codes and safety regulations.

In contrast, the other construction types listed do not utilize heavy timber as a primary structural component. Type I involves non-combustible materials, Type II consists of materials that may not be entirely non-combustible but provide less fire resistance than Type I, and Type III typically includes exterior walls that are non-combustible but may contain interior structural elements that are of wood or other combustible materials. This distinction underscores why Type IV is the appropriate classification for structures featuring heavy timber.