The diameter of holes bored in joists should not exceed what fraction of the depth of the joist?

The correct fraction regarding the diameter of holes bored in joists, which should not exceed one-third of the depth of the joist, is based on structural integrity guidelines specified in the North Carolina Mechanical Code and similar building codes. This rule is crucial to maintain the strength and stability of the joist when alterations are made, such as boring holes for mechanical services or wiring.

When holes exceed one-third of the joist's depth, there is a significant risk of compromising the joist's load-bearing capacity, potentially leading to sagging or failure under weight. The one-third limit is set as a standard to ensure that sufficient material remains surrounding the hole to support the structural loads without risk of buckling or cracking.

Understanding this guideline is essential for both compliance with building codes and ensuring safety in construction practices. Being aware of these limits helps prevent structural failures in buildings, thus safeguarding the occupants and the integrity of the structure.