What is the maximum diameter allowed for bored holes in single studs of exterior or load-bearing interior walls?

The maximum diameter allowed for bored holes in single studs of exterior or load-bearing interior walls is 40% of the stud depth. This guideline is established to maintain the structural integrity of the studs while still allowing for necessary plumbing, electrical, or other installations. Boring holes can weaken the studs, which are critical for the load-bearing capabilities of a wall, and limiting the size of these holes helps to mitigate any potential reduction in strength.

When bored holes exceed the specified maximum, it could lead to a decrease in the stud's ability to carry loads, potentially compromising the safety and stability of the structure. Therefore, adhering to the 40% guideline ensures that enough material remains to support ongoing loads and resist forces acting on the wall.

As for the other percentages given in the choices, they exceed the established safety margin for maximum hole diameter. For instance, a higher percentage could significantly jeopardize the stud's strength and overall wall performance, while smaller percentages might be unnecessarily restrictive compared to accepted standards.