Residential Building Inspector B1Floor ConstructionHard
An inspector observes a solid wood floor joist that has a notch cut into its top edge. The notch is located at the mid-span of the joist and has a depth equal to 1/4 of the joist's depth. What is the appropriate action for the inspector regarding this notch?
- ARequire reinforcement for the joist, as the notch is acceptable but weakens the member.
- BApprove the notch, as it is within acceptable limits for depth.
- CRequire repair or replacement of the joist, as this notch is not permitted.
- DApprove the notch, as long as the joist span is less than 12 feet.
Show answer & explanationAnswer & explanation
Correct answer: C. Require repair or replacement of the joist, as this notch is not permitted.
IRC R502.8.1 states that notches in the top or bottom of joists are not permitted in the middle one-third of the span. Even if it were allowed at this location, the maximum depth of a notch in the top or bottom of a joist is limited to one-sixth the depth of the joist, not one-fourth. Therefore, this notch is unacceptable and requires repair or replacement.
Why the other options are wrong
- A. Reinforcement might be considered for minor, permissible notches, but this notch is fundamentally not allowed at mid-span and exceeds depth limits.
- B. The notch depth (1/4) exceeds the maximum allowed (1/6) and is in a prohibited location.
- D. The joist span length does not negate the restrictions on notch location and depth at the mid-span.
Joist Notching Limits
Restrictions on the size and location of notches cut into solid wood joists to maintain structural integrity and prevent failure.
- Notches are prohibited in the middle one-third of the span.
- Maximum notch depth is 1/6 the joist depth (for allowed locations).
- Notches weaken joists, especially in critical stress areas.
Memory trick: Notches are Nasty if Not Nurtured by Norms.