Softwood-veneer plywood: Engineered wood panels for construction applicationsStructural plywood grades with pine or fir veneers are most often used for subflooring and sheathing. Stamps and other markings on plywood panels carry critical information about whether the product can be used for interior or exterior applications, and about the panel has been treated for rot resistance or fire retardance.

    Softwood-veneer plywood is a structural panel made up of thin wood layers (plies) bonded together into a large sheet. The wood grain of the plies forming the core run perpendicular to each other; this cross-grain orientation adds strength and rigidity to the sheet. The softwood face veneers on the top and bottom of the sheet are typically cut from pine, fir or spruce. Both interior- and exterior-grade sheets are available. In homebuilding, softwood plywood is used in much of the same way as oriented-strand board (OSB): for subflooring, and for roof and wall sheathing. However, there are many more types of plywood than OSB, making plywood an extremely versatile homebuilding product.

    Panel Sizes and Thicknesses
    The standard softwood sheet is 4 feet wide by 8 feet long, although many lumber dealers also stock 5-by-9-foot and 4-by-10-foot sheets. You can special order 4-by-10- and 4-by-12-foot sheets, though you'll likely have to buy an entire unit, which is usually about 150 sheets.

    Softwood plywood is available in a wide variety of thicknesses ranging from 1/4- to 1-7/16 inches thick. The most common homebuilding sheets by far are 1/2;-, 5/8- and 3/4-inch thick. The sheets come in both square-edged and tongue-and-groove panels.

    Softwood-Veneer Plywood: Basic Types
    Softwood plywood is most widely used as roof and wall sheathing, and for subfloors, but there are also several specialty products that every builder should know about.

    Plywood structural rating stamp

    Plywood structural rating stamp

    For wall and roof sheathing applications, panels ranging from 3/8- to 3/4- in. thick are most common, depending on the building's specific requirements. When building homes in hot climates, consider radiant barrier plywood. This specialty product has a foil face that reflects 97 percent of radiant heat to help reduce air-conditioning costs. On maximum span ratings on roofs, install metal clips onto the panel edges to prevent deflection. Be aware that it's often necessary to leave a 1/8-inch. gap between sheets to allow for expansion.

    Plywood Identification Stamp

    Plywood identification stamp

    For subfloors, you can double-up standard 1/2- or 5/8-inch-thick sheets, or use a single layer of thicker plywood. There are specially designed tongue-and-groove subfloor sheets that are 10 percent stiffer than standard plywood, and some manufacturers produce sound-dampening plywood, which measures up to 1-7/16 in. thick, that's ideal for subfloors. (See Georgia Pacific's Quietwood.)

    Other specialty plywood products include:
    •Textured plywood siding, which is often referred to by the tradename, T-1-11, is an exterior-grade plywood that has a rough-textured, grooved surface. It's occasionally used to side homes, but more often is applied to garages, barns, storage sheds, and planters. The 5/8-inch-thick sheets have shiplapped edges that produce undetectable joints. The sheets come with grooves spaced 4, 8 or 12 inches apart.
    •Sanded project panels are specifically designed for buildings cabinets, bookcases and furniture. They have very smooth surfaces that are ready for paint or stain. This smooth plywood sheet ranges in thickness from 1/4- to 3/4- inch. It comes in standard 4-by-8-foot sheets, and in several precut sizes including 2-by-2 feet., 2-by-4 feet, and 4-by-4 feet.
    •Beaded wall paneling is a decorative, grooved product that resembles traditional bead-board paneling. It's designed for interior use as wainscoting and wall paneling, and for weather-protected areas, such as porch ceilings and soffits. Beaded panels come in 4-by-8-foot sheets with the routed beads spaced about 1-1/2 inches on center.
    •A dense 10-ply sheet is produce specifically for the upholstery industry. This interior-grade, high-quality sheet comes in thicknesses ranging from 5/8- to 1-1/8 inches.

    Additional Resources
    American Plywood Association