Massachusetts Unrestricted Construction Supervisor License Practice Test

What is the maximum allowed span of a 2x10 floor joist, #2 grade Hem-Fir lumber spaced 16 inches on center in a bedroom in a single-family dwelling?

1. 19 ft 6 in.

2. 17 ft. 3 in.

3. 14 ft. 3 in.

4. 16 ft. 10 in.

The correct answer is: 16 ft. 10 in.

The correct answer reflects the allowable span of a 2x10 floor joist made from #2 grade Hem-Fir lumber spaced 16 inches on center when used in a residential context, such as a bedroom. In residential construction, the span tables guide builders on the maximum distances that different sizes and grades of lumber can effectively span while supporting the intended loads. For a 2x10 joist made of #2 Hem-Fir, the span must accommodate both live loads (the weight of furniture, people, etc.) and dead loads (the weight of the materials and structure itself). The maximum span of 16 foot 10 inches for these joists when spaced 16 inches apart strikes a balance between strength and deflection, ensuring the floor will be stable and not sag under typical loads. Understanding these limits is crucial for ensuring safety and adhering to building codes. Options that exceed this span generally compromise structural integrity, leading to potential safety issues. Thus, selecting the maximum allowable span is critical for compliance with building standards and for maintaining the quality and safety of the construction.