California Residential Inspector Practice Exam

The maximum allowable span for a 2 x 10 Douglas fir-larch #2 floor joist is influenced by various factors, including the type of load it is supporting and the spacing of the joists. In this case, the joist is supporting a living room, which typically has a dead load of 20 pounds per square foot (psf).

For a 2 x 10 Douglas fir-larch #2 floor joist spaced 24 inches on center, the adjustable span must be able to carry the applied load safely without structural failure. According to the general framing guidelines, the span tables for wood framing specify the limitations based on species, grade, load type, and spacing.

In this instance, the maximum allowable span for a 2 x 10 joist under the given conditions is determined to be 11 feet 8 inches. This length is carefully calculated by considering structural capacities, material strengths, allowable deflections, and safety factors prescribed by building codes.

The other options reflect spans that exceed the structural capabilities of the joist under the specified load conditions. Because a joist spanning beyond its maximum allowable distance can lead to excessive deflection, cracking, or failure, it's crucial to adhere to established guidelines to ensure the safety