What is the minimum nominal dimension for timber according to NDS?

The National Design Specification (NDS) for Wood Construction provides guidelines regarding the dimensions of structural timber, and it sets specific minimum nominal dimensions to ensure that lumber meets performance and design criteria. According to the NDS, the minimum nominal dimension for timber used in structural applications is 5 inches. This specification is crucial because it influences the strength and load-bearing capacity of the wood members, ensuring they perform adequately under various conditions.

Timber dimensions are pivotal in defining the structural capabilities and limit states that engineers must consider in their designs. Therefore, a minimum of 5 inches allows for sufficient cross-sectional area to achieve the desired strength and stability while recognizing the effects of factors such as wood species, moisture content, and load conditions. The minimum size also aids in accounting for manufacturing tolerances and ensuring structural integrity over the lifespan of the timber. The other options do not meet the requirements outlined in the NDS, as they either fall below the established minimum or do not apply to structural applications.