Notches on the ends of joists shall not exceed what percent of the joist depth?

• A. 10%
• B. 15%
• C. 25%
• D. 30%

Answer: (C)

The correct answer is that notches on the ends of joists shall not exceed 25% of the joist depth. This guideline is based on structural integrity and safety principles. Notching a joist affects its load-bearing capacity by potentially creating weak points. Allowing notches to be limited to 25% of the joist depth ensures that a sufficient amount of material remains to support the joist's structural requirements, reducing the risk of failure under load.

Exceeding this percentage could lead to compromised structural integrity, making the construction unsafe. Therefore, adhering to this limit is crucial in retaining the strength and stability of the framing system. The limitation is set out in many building codes and standards, reinforcing the importance of maintaining adequate support when modifying joists.