The maximum depth of a notch in the end of a floor joist is ____ of the depth of the joist

The maximum depth of a notch in the end of a floor joist is ____ of the depth of the joist

• A. 1/8
• B. 1/6
• C. 1/4
• D. 1/3

Answer: (C)

Notching a floor joist end reduces the cross-sectional area that carries the load, so the strength of the joist is governed by a depth limit relative to the joist’s thickness. At the end of a joist, where bending and shear are most critical for transferring loads to the support, the maximum allowed notch depth is one-quarter of the joist depth. Keeping the notch to this depth preserves enough material to maintain bending strength and helps prevent weakening, splitting, or failure under load. Notches smaller than that (like one-sixth or one-eighth) are permissible but not the maximum limit, while a notch as deep as one-third exceeds typical code limits and would compromise strength.

Notching a floor joist end reduces the cross-sectional area that carries the load, so the strength of the joist is governed by a depth limit relative to the joist’s thickness. At the end of a joist, where bending and shear are most critical for transferring loads to the support, the maximum allowed notch depth is one-quarter of the joist depth. Keeping the notch to this depth preserves enough material to maintain bending strength and helps prevent weakening, splitting, or failure under load. Notches smaller than that (like one-sixth or one-eighth) are permissible but not the maximum limit, while a notch as deep as one-third exceeds typical code limits and would compromise strength.