Plywood grades are determined by the veneer quality on the face and back of each panel. The first letter designates quality of face veneer (best side), while the second letter denotes the surface quality of the back of the panel. The letter "X" simply indicates the panel was manufactured with exterior type adhesive.
"A" Highest grade quality available. Can be defect free or contain small knots, providing they are replaced with wooden plugs or repaired with synthetic patch. May contain occasional surface splits that are repaired with synthetic filler. Surface is always sanded and provides for smooth paintable face quality.
"B" Second highest quality veneer grade. Normally a by-product of downgraded "A" quality veneer. Solid surface, but may contain small diameter knots and narrow surface splits. Normally repaired with wooden plugs or synthetic filler. Surface normally sanded smooth.
"C" Considered to be a lower end face quality, but a reasonable choice for general construction purposes. May contain tight knots up to 1-1/2" diameter, some open knot holes, some face splits, and discoloration. Some manufactures may repair the defects with synthetic filler. Panels typically not sanded.
"D" Considered to be the lowest quality veneer and often used for the back surface for construction grade panels. Allows for several knots, large and small, as well as open knots up to 2-1/2" diameter. Open knots, splits, and discoloration are acceptable. "D" grade veneers are never repaired or sanded. Not recommended for permanent exposure to weather elements.
Disclaimer: The above veneer grade classifications are merely interpretations and not considered to be all inclusive. For official grade designations for softwood plywood, visit the American Plywood Association (APA) website at
www.apawood.org. Or, visit the Hardwood Plywood & Veneer Association (HPVA) website at
www.hpva.org for questions pertaining to hardwood plywood products.
For further assistance in prescribing the proper panel product for your particular application,
inquire with a McCausey representative.