Plywood Grades - What Do the Letters Mean?

Softwood Plywood Grades

The grading system for softwood plywood is one of the easier puzzles to solve when it comes to buying lumber and wood project materials - thanks to the simple A-D letter system used to indicate the quality of the panel (see the chart below). The primary difference between one grade and another is the number of knot holes and voids you'll find in the layers of veneer - defects which occur naturally in just about all type of softwood plywood. The number of defects in a panel - and the amount of work a wood mill has done to repair the defects - will determine the grade and the price of plywood.

Plywood Grades A & B

The highest quality - and most expensive - types of softwood plywood are the A & B grades - which is perfect for shop projects like workbench plans. All large knots are replaced with football-shaped patches, which can be sanded and finished with the rest of the panel. Also, any gaps or voids along the edges of the panel are usually filled and smoothed off with wood putty. With the A & B grades, the number of repaired patches and voids on any given sheet will be low.

Plywood Grades C & D

The more economical types of plywood are the C & D grades. You'll see more repaired knots and voids on a sheet, and some defects will be left as is. This type of plywood grade is a good choice for projects where you will ultimately cover the plywood panel with some other type of cover material - like a smoother MDF sheet.

Not all home centers carry the higher-quality A & B grades of plywood. Try contacting your closest lumber distributor of woodworking supply store for more information and availability.