The maximum depth of a notch in the top or bottom of a floor joist is what fraction of the joist depth?

• A. 1/8
• B. 1/6
• C. 1/4
• D. 1/3

Answer: (B)

The maximum depth of a notch that can be safely made in the top or bottom of a floor joist is limited to one-sixth of the joist's total depth. This restriction exists to ensure structural integrity, as notching weakens the joist and can reduce its load-carrying capacity. Notches that exceed this depth can lead to increased risk of failure, especially if the joists are subjected to heavy loads or dynamic forces.

While the other fractions provided represent other common thresholds in construction practices, the one-sixth guideline is specifically designed to maintain the necessary strength and stability of the mind of a joist. This fraction ensures that enough material remains for the joist to function effectively while still allowing for practical modifications in construction.