Information on Plywood Flooring

Flooring Dimensions

• The common thickness for plywood is 3/4 inch and 4-by-8 feet is the usual width and length for a sheet of flooring plywood. Floor framing members must be of the correct size, length and spacing to support a floor without sagging. In general, larger timbers are used and they are placed closer together compared with those used in wood-frame wall construction.

Tongue and Groove

• Tongue and groove plywood is a common commodity for plywood subfloors. Each sheet has a tongue and a groove cut along the long edge of the plywood. These edges are interlocked during the installation process to strengthen the floor. In general, each sheet is attached to the floor joists with construction adhesive and stainless steel ring-shanked nails, for the combination of these construction methods adds even more strength to the floor.

Installation Pattern

• The sheets of plywood are applied to the floor joists in parallel rows in such a manner that all joints along the four-foot edge are staggered. That means each joint must fall on a different joist from adjacent plywood areas. At times blocking is used underneath the four-foot edge to add to floor stability and to decrease creaking of the floor.