According to building codes, what is the maximum allowable deflection in a floor joist for a residential building with a span of 10'-0"?

The maximum allowable deflection in a floor joist is typically determined by building codes to ensure structural integrity and comfort for occupants. For residential buildings, a common guideline is that the maximum deflection should not exceed 1/360 of the span of the beam.

In this case, with a span of 10 feet (which equals 120 inches), the calculation for maximum allowable deflection would be:

1/360 of 120 inches = 0.33 inches, which is equivalent to 1/3 inches.

This means that if the joist deflects more than this amount under load, it could lead to issues such as squeaking floors, compromised structural integrity, or discomfort for those using the space. Therefore, when considering the options provided, the choice of 1/3 inches is correct, as it aligns with the recommended limits set by building codes for deflection in residential floor joists.