What Is ULX Plywood?

B Side

• The veneer in ULX plywood is rated BC. The outer, B-graded surface denotes wood with the second-highest grade level, after A-graded or N-graded veneer suitable for fine furniture or cabinetry. B-graded veneer presents a solid surface -- important for prevention of weathering in exterior-grade plywood. Unlike N- or A-graded veneer, however, it may contain small, round knots, patches and round plugs. For this reason, ULX plywood should be painted, sealed or varnished in exterior applications.

C Side

• The inner veneer surface of ULX plywood denotes wood with the second-lowest grade level for plywood, above D-grade veneer. In addition to patches and knots, C-grade plywood may have small knotholes. C-grade veneer is the lowest quality veneer allowed in exterior-grade plywood. To reduce weather damage, the C-graded side, identifiable by its rougher and more irregular surface, should be oriented toward the inside of a structure when building with a BC-X plywood like ULX.

Glue

• The "X" in ULX designates exterior-grade plywood. Manufactured with waterproof glue bonding the layers of veneer together, the product is weatherproof when correctly finished. The "X" designation may also refer to plywood graded Exposure-1, which is suitable only for situations in which weather exposure is temporary. Exposure-1 plywood uses the same waterproof glue as is found in ULX plywood but has lower quality, D-grade veneer that renders it less stable than ULX plywood in wet conditions.

Suitability

• ULX plywood is suitable for any non-marine application in which a visually appealing, high-quality natural finish is unnecessary. The irregular knots and patches make it a poor choice for building unpainted furniture or cabinets, as does the fact that it is made of pine, a softwood. As long as ULX plywood is painted or otherwise sealed, it can be used outside. However, the C-grade veneer is too low to qualify it as a marine-grade product, since marine-grade plywood must be graded BB or better.