CDX Grade is a standard that has been established by American Plywood Association (APA). “CDX” is not the name of a plywood grade. Rather, CDX stands for “C-D Exposure 1 plywood”. C-D refers to the appearance and treatment of the faces of the plywood. One is rated “C” grade and the other side is rated “D” grade. The letter “X” means the glue of the plywood is exterior glue. However, CDX plywood is not exterior plywood. Usually the core veneers for CDX plywood are not as good as exterior plywood. CDX plywood is moisture resistant but cannot be exposed to weather for extended periods.
CDX plywood is a very economical and efficient construction plywood. Usually CDX plywood are sanded but not finished or its knots plugged. As a result, the face and back of CDX plywood is rough. Some knots and knot holes exist in the face and back as well.