Residential Building Inspector B1Floor ConstructionMedium
During an inspection of a floor system utilizing I-joists, the inspector observes several holes drilled through the web of the I-joists for plumbing lines. What is the most critical factor an inspector must verify regarding these holes?
- AThat the holes are located at least 2 inches from the top and bottom flanges.
- BThat the holes are located only in the middle one-third of the joist span.
- CThat the diameter of the holes does not exceed 1/2 of the joist's web depth.
- DThat the holes are within the allowable size and location specified by the I-joist manufacturer.
Show answer & explanationAnswer & explanation
Correct answer: D. That the holes are within the allowable size and location specified by the I-joist manufacturer.
Unlike solid sawn lumber, engineered wood products like I-joists are highly sensitive to alterations. The IRC (R502.8.2) explicitly states that cuts, notches, or holes in engineered wood products shall be in accordance with the manufacturer’s recommendations. This is the paramount rule for I-joists.
Why the other options are wrong
- A. This is a general rule for solid lumber, but manufacturer's specs override for I-joists.
- B. This is incorrect; holes are often restricted from the mid-span area in I-joists, or specific zones are designated by the manufacturer.
- C. This is a general rule typically applied to solid sawn lumber, not I-joists, where web holes are much more restrictive.
I-Joist Alteration Rules
Specific limitations on drilling holes or cutting notches in I-joists, which are strictly dictated by the manufacturer's engineering specifications.
- Manufacturer's instructions supersede general code for solid lumber.
- Web holes are common but have precise size and location limits.
- Flanges should generally not be cut or notched.
Memory trick: Manufacturers' Manuals Mandate Modifications.