What is the minimum nominal dimension for wood roof decks in Type IV construction?

In Type IV construction, which is often referred to as "heavy timber," there are specific requirements for the materials used in various components, including roof decks. The minimum nominal dimension for wood roof decks in this type of construction must be sufficient to meet fire safety and structural integrity standards.

A nominal dimension of 2 inches is common in heavy timber construction for roof decks because it provides an adequate thickness that can support the loads typically expected, while also offering enhanced fire resistance compared to thinner options. This dimension allows for the use of heavy timber members that are capable of performing well in fire scenarios, as well as contributing to the overall durability and performance of the structure.

The other options present dimensions that exceed this minimum requirement, making them unnecessary for compliance while potentially increasing weight and cost without additional benefit in typical applications. Thus, a 2-inch nominal dimension effectively balances performance criteria and regulatory requirements for wood roof decks in Type IV construction.