Specifications on Outdoor Plywood

Sizes

• Plywood sheets come in nearly any size, but most lumber yard stores carry the standard size of 4-foot by 8-foot sheets. Many stores can even cut the wood to smaller sizes upon request. Plywood also comes in a variety of widths, and the precise thickness is always listed as a stamp on the plywood.

Outdoor Types

• CDX plywood is used for sheathing under roofing or exterior siding. ACX is a better grade of exterior plywood and is sanded smooth for paint. Oriented strand board (OSB) is an engineered wood product made of wood chip slices mended together in a patchwork design, and it is most commonly used for subflooring. Medium density overlay (MDO) is used primarily for road signs. Marine plywood is made with glue that can tolerate water submersion, so it is ideal for building boats, docks and outdoor decks.

Trademark Stamp

• Plywood panels have a stamp on them that contains a lot of information. The first word after the Engineered Wood Association's "APA" logo describes the ideal purpose of the wood, for example, "Sheathing" means the wood is perfect for subfloors or similar sheathed uses. The trademark stamp also gives a product standard description below a single black bar. The product standard will further indicate the plywood's recommended use.

Rating

• The first number on the plywood's stamp is the span rating, which is the recommended distance between two supports beneath the wood. The plywood's stamp also indicates the bond rating, which describes the specific type of glue used on the wood. For example, "Exterior" labels the plywood for outdoor use, while "Exposure" means the plywood can survive in mild weather conditions, but not in all outdoor weather conditions.