Plywood is a staple material in the construction and woodworking trades. Here's how to recognize the grades and choose among them.
Whether you work in construction or in a wood shop, plywood is a material you can’t avoid. I’ve used it outdoors to sheath roofs and walls, indoors for subfloors and room dividers, and in the shop for multiple cabinet and furniture projects. Plain Mdf
Obviously, the plywood you use to make a custom cabinet must be a higher grade than what you use for roof sheathing. But what does the lumber industry mean by “grade,” what are the different grades, and what are they used for?
“Plywood is graded through four main levels, A, B, C and D,” says Josh Kou, a lumber pro with a lifelong interest in hardwood.
Grade A is the top grade, and it’s perfect for cabinetry and furniture making. Grade D is at the bottom of the scale. According to Artem Kropovinsky, an interior designer with more than a decade of experience, Grade D is “used for structural purposes where the surface will be hidden.”
Intermediate grades are suitable for some cabinetry projects (mostly Grade B) and other utility purposes (Grade C).
Here’s the lowdown on plywood grading to help you choose the right material for your project.
Josh Kou is a second-generation lumber pro who traveled extensively through Asia learning woodworking techniques. He’s the operations manager for NorthCastle Hardwoods.
Artem Kropovinsky is an interior and cabinet designer and the founder of NYC-based Arsight. His designs have been featured in Architectural Digest, The New York Times, Forbes, Business Insider and Domino. He has extensive knowledge of plywood and its uses.
Slice wood from a tree trunk in thin layers, glue them together in alternating directions, and you’ve got plywood.
“Almost all plywood in the U.S. is made from either Douglas fir or western larch, both of which are softwoods,” says Kou. “However, Grade A plywood is often finished with a hardwood veneer. It is an affordable and sustainable way to present hardwood.”
Plywood comes in sheets measuring four by eight feet (1,220 x 2,440 millimeters), in thicknesses ranging from 1/4-in. (6-mm) to 1-3/16-in. (30-mm).
Because wood layers are glued in cross directions, plywood is more stable than solid wood and rarely warps or buckles. This makes it a good alternative to solid wood for construction and cabinetry, and often the preferred material.
RTD stands for “Resistance Temperature Detector.” Manufacturers monitor the temperatures of each layer during production of RTD plywood, ensuring a more reliable glue bond and a better-wearing final product.
A product where manufacturers use a waterproof adhesives and wood preservatives to make highly moisture-resistant sheets. The veneer may be a hardwood or softwood, and it must be free from defects.
As the name suggests, boat builders use this type of plywood. Contractors like it for sheathing and subfloors in areas subject to excessive moisture.
Identified by the rating X, this product is also moisture-resistant. But manufacturers use lower-grade adhesives to produce it, and the softwood veneer may have knots and other defects.
The four plywood grades are as follows:
Both sides of a sheet don’t always have to be the same quality, because in many applications only one side is visible. Here’s Kou’s rundown of uses for the most common sub-grades:
For quality, AA, but it really depends on the use. If you’re doing outdoor building, AAX, ACX and BCX are preferable.
Again, that’s AA. A single 4- by 8-ft. sheet of 3/4-in. maple-faced plywood, sanded on both sides, costs almost $90. By contrast, a 3/4-in. sheet of utility-grade CDX plywood costs less than $60.
For clear finishing, any plywood with one A-grade face is suitable for cabinets. For painting or veneering, you need at least one B-grade face.
Same answer. You need at least one A-grade face for clear finishing and one B-grade for paint or veneer. For exterior furniture, use AAX, ACX or BCX.
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