What is the minimum nominal size for wood columns in Type IV construction?

In Type IV construction, also known as "Heavy Timber" construction, the minimum nominal size for wood columns is crucial for ensuring structural integrity and fire resistance. Wood columns in this type of construction must have a nominal dimension that allows for greater durability and load-bearing capacity.

Choosing 8 inches as the minimum nominal size complies with the requirements established by building codes, which aim to provide adequate fire resistance and structural stability. This larger dimension allows for better performance in terms of resisting both axial loads and lateral forces that may occur during events such as heavy winds or seismic activity. Additionally, larger timber sizes have better fire resistance properties, as they will char on the surface while maintaining structural integrity for longer periods when exposed to fire.

This requirement is grounded in the fact that heavier and larger timber sections can withstand the conditions that Type IV buildings may face, including thermal effects, making it a necessary specification for safety and performance in construction standards.