Choose the right plywood for your project

A primer on grades, composition and exposure ratings

By Inman News Feed
Add Comment Add Comment | Comments: 0 | Posted Mar. 2, 2012

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Exposure ratings

Softwood plywood is also rated according to one of four exposure ratings, which indicates its durability when exposed to moisture. Those ratings are:

Exterior: Has a fully waterproof glue joint, and is designed for use in areas that are permanently exposed to moisture or weather.

Exposure 1: Also has a fully waterproof bond, and is designed for use where the construction process will subject them to long periods of weather exposure before they are fully protected.

Exposure 2: Intended for use in protected construction areas where they will be exposed only to moderate moisture or weather conditions.

Interior: Limited strictly to use in protected interior environments.

Hardwood plywood grades

Plywood is also available with hardwood veneer faces, for use in cabinets, furniture and other projects where appearance is important. Hardwood plywood usually has softwood veneer inner plies, but may also have an inner core of lumber, particleboard or other material. There are dozens of different types of hardwood plywood, from more common grades such as birch and oak, to exotic species from all over the world.

As with softwood plywood, hardwood veneers may be rotary cut or sliced. If they're sliced, the veneers may be slip-matched, meaning they're butted side by side as they're cut off the log, or book-matched, meaning that every other one is flipped over, creating a mirror image of the one before it. The two different types of matching can greatly affect the appearance of the sheet, so it's worth looking at.

Sheet sizes are similar to softwood plywood, although a multi-ply Baltic birch plywood in a 5-foot-by-5-foot sheet is also common among cabinetmakers. Thicknesses are less uniform than softwood plywood, due to thinner veneers and the number of sheets that are imported from countries that manufacture to different standards.

Hardwood plywood has a slightly different grading system, and it can be a little less uniform than that of softwood plywood. Basically, A-D grades (best to worst) apply to the face of the sheet, and 1-4 applies to the back of the sheet. So an A-1 sheet is the best, with a good veneer on both sides.

An A-4 would have a good grade on the front, with a back that has knots, blemishes and repairs; it would be used where only one side of the sheet will be seen.

Remodeling and repair questions? Email Paul at paulbianchina@inman.com. All product reviews are based on the author's actual testing of free review samples provided by the manufacturers.

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