How Much Can You Notch a Floor Joist

The maximum depth of a notch at the end of a joist (where it rests on a wall or beam) can’t exceed one-quarter of the joist depth. Maximum notch depth in the outer third of a joist is one-sixth of the joist depth. Limit the length of notches to one-third of the joist depth.

Can I cut a notch in a floor joist?

A: Floor joists occasionally need to be notched or drilled during construction, but you should take pre cautions not to weaken the structural strength of the framing member. … You can cut a notch at the end of the joist to 1/4 of the joist’s depth (maximum).

What is the maximum allowed distance of a notch in a joist from a bearer or wall?

The maximum allowable depth of notches is one fifth of the joist or rafter depth or 32 mm, whichever is less. Holes may only be located within a length measured from the face of a support that is no more than three times the depth of the joist or rafter.