What is the minimum size wood stud and stud spacing for a wall supporting two floors and a roof ceiling assembly?

The minimum size wood stud for a wall that must support two floors and a roof ceiling assembly is a 2x6 with a stud spacing of 16 inches on center. This standard is informed by building codes and structural engineering principles that consider load-bearing requirements for such configurations.

A wall supporting multiple floors and a ceiling needs to be stronger than a typical interior wall, which is often built with 2x4 studs for non-load-bearing purposes. The use of 2x6 studs increases the structural integrity and load-bearing capacity, ensuring that the wall can adequately support the combined weight of the floors above, as well as the roof structure.

Stud spacing at 16 inches on center is a common practice that balances material efficiency with structural strength. This spacing allows for adequate support while also permitting sufficient insulation and space for other utilities.

In contrast, larger sizes such as 2x8 or 2x10 are generally over-engineered for this specific application, unless there are unique load scenarios or spans that require additional strength. However, for general construction practices, 2x6 studs at 16 inches on center meet the requirements for supporting two floors and a roof structure effectively.