5/8 4 x 8 marine fir plywood
Marine plywood is a premium grade panel. Per the American Plywood Association(APA) grading standards, Marine-grade plywood consists entirely of Douglas-fir or Eastern Larch. To comply with this standard, all internal plies of veneer must be B-grade or better. In descending order Fir plywood grades are A,B,C,D. B-grade veneer may have knots but no knotholes while A-grade veneer can have neither knots or knotholes. Both A and B grades allow wood or synthetic patches. Up to 18 wooden patches are allowed per side (usually in the shape of a football). This is to repair the knots and knot holes which are prevalent in both Douglas-fir and Eastern Larch. The maximum core-gap on the interior veneers is an 1/8 of an inch. Its bond classification is Exterior and the glue is a moisture resistant structural adhesive. Due to these standards, boat builders like this product.
Toledo Plywood stocks this product in 1/4”, 3/8”, 1/2”, 5/8” and 3/4” 4′ x 8′ sheets. Because you might need a smaller piece, Toledo Plywood has cut sizes of 2′ x 8′, 4′ x 4′ & 2′ x 4′.
Marine plywood contains no chemical treatment to increase its resistance to decay. If finished on all six sides sides and maintained with a good quality exterior sealant to prevent moisture from entering the board, this product will give you years of excellent service.