To avoid the kind of plumbing drop shown above, most manufacturers allow I-joists to be moved up to 3 inches from the specified spacing without a redesign.
To avoid the kind of plumbing drop shown above, most manufacturers allow I-joists to be moved up to 3 inches from the specified spacing without a redesign.

As an engineer with the APA/Engineered Wood Association, one of my jobs is to investigate defect claims and job-site callbacks involving the use of structural panels and engineered lumber. Most of the cases I’ve seen over the past 18 years have been the result of easily correctable errors made by the builder. Some installers fail to follow proper installation guidelines and standard framing practices. Others forget that engineered framing and sheathing are still natural wood products: Their strength characteristics are affected by grain and they’re sensitive to moisture, so they need to be handled and installed accordingly. Here are some of the most common problems I’ve encountered, along with the solutions I typically recommend.

Cutting Holes in I-Joists. In an I-joist, the web carries dead and live loads out to the supports. Under normal conditions, loads accumulate from midspan outward, with half going to one support and half to the opposite. Because this places the greatest amount of shear within the web at the inside face of each support, you need to minimize...

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