What is the maximum depth of a notch in the top or bottom of a floor joist relative to the depth of the joist?

The maximum depth of a notch in the top or bottom of a floor joist is crucial for maintaining the structural integrity of the joist. According to accepted building codes and practices, the typical maximum notch depth allowed is one-sixth of the total depth of the joist. This limitation helps prevent compromising the strength and load-bearing capacity of the joist, ensuring safety and longevity in construction.

Notching a joist more than this permitted depth can lead to a significant decrease in its ability to carry loads, potentially resulting in structural failure. This is why a limitation of one-sixth is established; it allows for the necessary adjustments in installations, such as running wiring or plumbing, while still preserving the key structural elements of the joist.

In contrast, notches deeper than this, such as those suggested in the other choices, could be detrimental to the joist's performance, potentially leading to sagging or even collapse under load, which is why they do not represent safe practices according to building codes.