Heavy timber structural members have dimensions of at least:

Heavy timber structural members are defined by their substantial dimensions, which contribute to their strength and fire resistance. Specifically, for a timber member to be classified as heavy timber, it must have a minimum nominal dimension of 8 inches. This thickness is significant because it allows the wood to achieve desirable fire resistance qualities, as the larger cross-section slows down the rate at which the member burns.

When subjected to fire, heavier timber can provide a level of structural integrity that lighter timbers cannot, as the thickness helps to insulate the interior from heat and flames. This characteristic is particularly crucial for structures that need to meet stringent fire safety codes. Buildings made of heavy timber can be more resilient during a fire, giving occupants more time to evacuate and firefighters more time to manage the situation.

Understanding this classification helps safety officers assess risks and implement appropriate safety measures during fire events. The other dimensions, while important in their contexts, do not meet the established minimum for heavy timber classifications, which is firmly set at 8 inches.