Q. Most sheathing manufacturers recommend that panels be spaced at the edges andends. Since panels measure a full 4x8 feet, the only way I’ve been able to provide this spacing (and maintain standard joist and stud layout) is by trimming the ends and edges of the sheathing panels. Why don’t manufacturers size the panels 47 7/8 by 95 7/8 inches?

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.