Exterior plywood can be purchased at most major home improvement stores, including Home Depot, Menards and Lowe's. When shopping for exterior plywood, look for identifying marks that distinguish the plywood as exterior quality. Commonly, the marking “CDX” is used to denote exterior plywood.
Exterior plywood is not limited to outdoor use. In fact, due to its water-resistant qualities, exterior plywood is commonly used for many interior projects, such as counter-tops, surface areas around sinks, and as sheathing over studs. Hardware stores identify exterior plywood by including an “X” in the identification marks. Stores organize the plywood by wood species, thickness, price, panel grade, common width or common length.