Cutting or notching of wood studs not greater than 40 percent of their depth is permitted in nonbearing partitions.

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

Answer: (B)

In nonbearing partitions, the wall studs can be notched enough to run wiring or plumbing without weakening the wall too much. The limit you’ll see in practice is 40 percent of the stud’s depth. That means, for a typical 3.5-inch-deep stud, you can notch about 1.4 inches. This balance keeps enough wood to resist bending while still allowing the required openings. Since 40 percent is the maximum allowed, any deeper would not be permitted, while 30 or 20 percent would be allowable but not the full limit.