Both hardwoods and softwoods are used for floors. Hardwoods most commonly used are maple, beech, birch, oak, and pecan. Softwoods are yellow pine, Douglas fir, and western hemlock. The hardwoods are more resistant to wear and indentation than softwoods.
Hardwood strip floorings are available in thicknesses of 11⁄32, 15⁄32, and 25⁄32 in and in widths of 11⁄2, 2, 21⁄4, and 31⁄4 in.
Softwood strip flooring usually is 25⁄32 in thick and can be obtained in widths of 23⁄8, 31⁄4, and 53⁄16 in.
Solid-unit wood blocks for floors are made from two or more units of stripwood flooring fastened together with metal splines or other suitable devices. A block usually is square. Tongued and grooved, either on opposite or adjacent sides, it is held in place with nails or an asphalt adhesive (Table 11.12). Blocks 25⁄32 in thick are made up of multiples of 11⁄2- and 21⁄4-in strips; blocks 1⁄2 in thick are composed of multiples of 11⁄2- or 2-in strips.
A laminated block is formed with plywood comprising three or more plies of wood glued together. The core or cross bonds are laid perpendicular to the face and back of the block. Usually square, the block is tongued and grooved on either opposite or adjacent sides. The most common thickness is 1⁄2 in, but other thicknesses used are 3⁄8, 7⁄16, 5⁄8, and 13⁄16 in. Laminated blocks are installed with adhesives (Table 11.12).
Average moisture content of wood flooring at time of installation should be 6% in dry southwestern states, 10% in damp southern coastal states, and 7% in the rest of the United States (‘‘Moisture Content of Wood in Use,’’ U.S. Forest Products Laboratory Publication No.1655, Madison, Wis.). The U.S. Forest Products Laboratory also recommends heating the building before installing any type of wood flooring, except when outdoor temperatures are high. Bundles of flooring should be opened and stored in the building before installation. Leave at least 1 in of expansion space at walls and columns.
Specifications for wood floors on concrete, gymnasium floors, or other special designs or conditions may be obtained from associations of wood flooring manufacturers and installers.