What must be the minimum width of planks that are set on edge close together in Type IV construction?

In Type IV construction, which is known as "Heavy Timber" construction, the use of planks set on edge (also referred to as "laminated timber") plays a significant role in both the structural integrity and fire resistance of the building. The minimum width of these planks is established by building codes to ensure adequate support and safety.

A minimum width of 5 inches for planks set on edge is outlined in various building codes and standards associated with Type IV construction. This specification is intended to enhance the load-bearing capacity of the timber while also providing a sufficient cross-sectional area to resist fire exposure more effectively. Wider planks are better suited for distributing loads evenly and can also provide better fire resistance due to their greater mass.

Adhering to this minimum width requirement helps minimize the risks associated with structural failure, particularly in the context of fire, as wider timbers are less likely to be fully consumed in a fire scenario. This is crucial for ensuring occupant safety and the overall longevity of the structure.