Which condition describes dry lumber according to the NDS?

The definition of dry lumber according to the National Design Specification (NDS) outlines that wood is considered dry when its moisture content is less than or equal to 19%. This criterion is essential because the moisture content of wood affects its strength, stability, and dimensional changes. When lumber has a moisture content above this threshold, it is likely to shrink, swell, or exhibit other undesirable behaviors as it dries out, which can compromise the integrity of structures.

The other options reflect various moisture content levels that do not align with the NDS's specific definition of dry lumber, emphasizing the importance of maintaining moisture levels below or equal to 19% for practical structural applications and standards.