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Like all wood products, plywood and oriented strand board (OSB) will expand or shrink slightly with changes in moisture content. If wood structural panels are tightly butted, leaving no room for expansion, buckling can occur. While buckling is not a structural deficiency, it may result in aesthetic or serviceability issues, such as the appearance of wavy roofs and walls or uneven floors. This can mean costly, time-consuming callbacks.

To avoid buckling, follow this simple guideline: Install plywood and OSB with a 1/8-inch space between panel edge and end joints. Determining proper spacing is as easy as keeping a 10d box nail handy; slip the nail in between panels, snugly but not forced, and if it stays put, you’ve created the proper gap.

First and foremost, always follow recommendations and installation requirements from the manufacturer for the panels and application you’re installing.

This how-to article is part of the Builder Tips series of publications from APA-The Engineered Wood Association. To view more helpful strategies, visit

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