A. Bryan Readling, P.E., senior engineer at the APA/Engineered Wood Association, responds: Midspan blocking — typically used with sawn lumber joists — isn't normally recommended for I-joist floor systems. In a floor framed with sawn lumber, blocking helps joists share loads so that a weaker joist may be reinforced by stronger joists on either side. Blocking also helps to vertically align twisted joists, improving their performance. But since I-joists are already straight and uniform in strength, blocking doesn't add significantly to their performance.
Construction adhesives prevent movement of the floor sheathing relative to the joists, eliminating a common source of squeaks: vibrations created as fasteners rub up and down within the floor sheathing. Glued floor sheathing also increases each joist's effective cross-sectional area and stiffness. The enhanced bond allows the joist and sheathing...
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