Notching or cutting wood studs in nonbearing partitions is permitted up to 40 percent of depth.

• A. 30 percent
• B. 40 percent
• C. 20 percent
• D. 50 percent

Answer: (B)

Notching or cutting into wood studs in nonbearing partitions is allowed up to 40 percent of the stud depth because these walls aren’t transferring vertical loads. That limit gives enough room to pass plumbing, electrical conduits, or small-diameter ducts while still leaving most of the stud’s cross-section intact to resist bending and shear. For a typical 2x4 with an actual depth of about 3.5 inches, a 40 percent notch is roughly 1.4 inches deep. Going deeper would weaken the stud too much and risk instability, which is why the code sets this limit. The other percentages are either more restrictive or exceed what the code allows for nonbearing partitions, so they aren’t the correct rule here.