I get questions about plywood grades from time to time so I figured I would see what it is already out there about plywood and compile it for you here. There is some good stuff.
Plywood Grades Sources:
- Plywood - this is like a plywood 101 and 201 combined. It covers hardwood plywood, how plywood is made, uses for plywood, and plywood grades.
- Plywood Grades Stamps - Even though this is a lesson specific to TECO, it still applies to the plywood grades stamps on most plywood.
- Softwood Plywood Grades - Informative article that sticks closely to construction plywood grades. Excellent read if you are about to building something with plywood.
- Hardwood Plywood Grading Rules - Sticks to hardwood plywood grading and gives a very clear explanation.
Plywood Grades (from "Plywood")
CDX: Lowest grade of exterior plywood available usually used for sheathing on roofs or walls. Can be used for utility purpose. Available in 3/8", ½", 5/8" and ¾"thicknesses in 4x8 pieces.
5/8" Underlayment: 4x8 used for subflooring, when a smooth surface is needed. This plywood is made with exterior glue.
BC Plywoods: BC grade plywoods have one finished face usually yellow pine made with exterior glue and is available in 3/8", ½", and ¾" in 4x8 pieces.
Finished and Special Purpose Panels Plywood Grades
AC Plywoods: AC grade plywoods have one finished face usually Douglas Fir made with exterior glue and is available in ¼", 3/8", ½, 5/8" and ¾" pieces.
Luan Plywood: A cheap grade of Mahogany plywood available in 1/8" and ¼" 4x8 pieces. Perfect for Cabinet backing, or any utility purpose.
BB Plyform: ¾" 4x8 sheets finished 2 faces, oiled for easy removal after being used for concrete forming.
Hardboard: Standard pressed hardboard 4x8 sheets available in 1/8" and ¼" thicknesses. Pegboard available in the same sizes.
Homasote: ½"x 4 x 8 sound board. Used on floors or wall for sound barrier, also great as bulletin boards.
A/B Marine: Marine plywood available in ¼", 3/8", ½" and ¾" thicknesses 4x8 sheets (sold by the sheet only). Marine plywood is usually used in boat making application. The same exterior glue as in all exterior construction grade plywoods is used. The main difference, and what makes marine plywood more expensive is the voidless inner plys that make up the plywood. Inner plys must be solid. (A boats motor causes vibration, if a plywood with inner voids is used the plywood can delaminate. Marine plywood has all voidless inner plys.)
MDO: Medium Density Overlay is regular plywood core with a smooth 10 mill paper applied to one or both faces. The smooth paper facing is an excellent surface for painting signs. If sealed and primed properly MDO can be used outside. Thicknesses available in 3/8", ½", ¾" GIS an G2S. 4x8 sheets.
MDF: Medium Density Fiberboard, a heavy fibered board used in cabinet making. Excellent for paint applications. What Cabinet makers like about the product is it’s routeable surface. MDF is also used in making speaker cabinets. Sizes available are ½" and ¾" sheets.
CCA Treated Plywood: A grade of "green" CCA treated plywood is chemically treated to prevent corrosion. Re-Dried after treatment, this plywood is excellent for exterior application.
Hardwood Plywoods: Species types are: Birch, Red Oak, Cherry, Mahogany, Walnut and Maple. Sizes are available in ¼", 3/8", ½", ¾" in most species types. Most Hardwood plywoods stocked are graded A-1 which means good on one face. Other grade designations are Cabinet Grade and paint grade for more common used birch panels.