According to the Code, notches allowed in the top or bottom of joists shall not exceed what fraction of the depth of the joist?

According to the Code, notches allowed in the top or bottom of joists shall not exceed what fraction of the depth of the joist?

• A. 1/3
• B. 1/6
• C. 1/4
• D. 1/5

Answer: (B)

Notches weaken a joist where bending stresses are the highest, so the code sets a strict limit to keep enough of the cross-section intact. The depth of any notch cut into the top or bottom of a joist cannot exceed one-sixth of the joist’s depth. This keeps the joist strong enough to carry loads while still allowing some opening for services. For example, a 9-inch-deep joist can have a notch up to 1.5 inches deep. If you need larger openings, you’d have to use a different approach or reinforce the joist to meet structural requirements.

Notches weaken a joist where bending stresses are the highest, so the code sets a strict limit to keep enough of the cross-section intact. The depth of any notch cut into the top or bottom of a joist cannot exceed one-sixth of the joist’s depth. This keeps the joist strong enough to carry loads while still allowing some opening for services. For example, a 9-inch-deep joist can have a notch up to 1.5 inches deep. If you need larger openings, you’d have to use a different approach or reinforce the joist to meet structural requirements.