The different plywood grades
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Typical plywood grades and characteristics
From blemish-free and sanded smooth to gaping spaces around knots and cracks, each grade of plywood has different characteristics.
In the United States, there are four basic softwood (construction) plywood veneer grades you need to worry about: A, B, C and D. Occasionally, you may run into a fifth grade called “C-plugged.”
Each sheet will have two grades, such as AC. The first letter is the face veneer grade, and the second is for the back veneer. Some plywoods have a third letter, X, that designates them for exterior use. From highest quality to lowest, here's what to look for:
“A” Grade. Sanded smooth, paintable. Though some neatly made manufacturer repairs are acceptable, you should have little trouble finding A-grades that are free of repairs and knots.
“B” Grade. Solid surface with some repairs, usually football-shaped patches and/or wood filler. May have tight knots (no chunks of wood missing) up to 1 in. Some minor splits.
“C” Grade. Tight knots to 1-1/2 in. and knotholes to 1 in., some splits and discoloration.
“D” Grade. Knots and knotholes up to 2-1/2 in. Some splits. Generally no repairs.
Even within the different plywood grades, you'll likely find a wide range in the number of repairs or defects. For more information about softwood plywood, visit the American Plywood Association. You'll find facts about plywood uses, grading and specs.