What is the maximum notch at the end of a joist as a fraction of its depth?

What is the maximum notch at the end of a joist as a fraction of its depth?

• A. Two Inches
• B. One Fourth Of Depth
• C. One Inch
• D. One Third Of Depth

Answer: (B)

When you cut into the end of a joist, you’re removing material right where the member must resist bending and transfer load to the support. To keep enough cross-section left to carry those forces, codes cap end notches at a fixed fraction of the joist depth. The limit is one-quarter of the joist depth. This keeps enough material in place to maintain strength and prevent failure at the bearing end. If the notch were deeper, the remaining wood would be too weak to handle the bending and shear stresses near the support. So, for a joist that’s 9 inches deep, the notch at the end should not exceed about 2.25 inches; for 12 inches deep, not more than 3 inches. The other options are not universal fractions of depth for end notches, so the one-quarter rule is the correct standard here.

When you cut into the end of a joist, you’re removing material right where the member must resist bending and transfer load to the support. To keep enough cross-section left to carry those forces, codes cap end notches at a fixed fraction of the joist depth.

The limit is one-quarter of the joist depth. This keeps enough material in place to maintain strength and prevent failure at the bearing end. If the notch were deeper, the remaining wood would be too weak to handle the bending and shear stresses near the support.

So, for a joist that’s 9 inches deep, the notch at the end should not exceed about 2.25 inches; for 12 inches deep, not more than 3 inches. The other options are not universal fractions of depth for end notches, so the one-quarter rule is the correct standard here.