A.Ed Keith responds: The APA, as well as most panel manufacturers, recommends 1/8-inch spacing at the edge and end of panels. APA manufacturing standards are designed to accommodate this spacing by permitting a full 1/8-inch plus-or-minus tolerance on the length and width of sheathing panels. Many manufacturers do, in fact, cut their panels a little short and narrow. While the amount of cutback varies among manufacturers, it’s typically 1/16 inch. Why not a full 1/8 inch? The 1/16 inch may be a compromise to avert rejected panels that are too short or out of tolerance.

Ed Keith is a senior engineer at APA - The Engineered Wood Association in Tacoma, Wash.

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