What is Plywood?

Definition of Plywood in Construction
Manufactured sheathing made up of wood products and clue. Plywood comes in various sizes, 4 X 8 being the most popular and is available in different thicknesses, dependent upon the use of the sheet.

The number of plys ( layers ) used in the build-up of the sheet, will determine its strength and durability as well as its thickness. Plywood comes in various surface finishes as well as various species of wood. Finished plywood can be extremely expensive and is used for furniture grade applications, whereas fir plywood is used as a primary exterior sheathing for walls, roofs, floors, etc. Plywood obtains its strength from the buildup of layers of wood and glue. The orientation of the layers, is engineered to produce the most strength and durability. Plywood, when being installed, is normally laid perpendicular to the supporting floor joists, rafters, etc. In this manner the layout of the plywood spans more of the supporting members. P&S plywood references a plug and sanded technique that is applied to plywood used for a sub base for a finished floor, or other application requiring a more even surface. The development of plywood has basically eliminated the use of individual roofing or siding boards as a substrate for the finish roofing or siding application. T&G plywood consists of a tongue and groove . This plywood is manufactured, with a tongue of wood on one of the long sides and a groove on the other long side. This allows the matting of the individual pieces of plywood upon installation, creating a strong and cohesive surface. In many high end homes, the use of a T&G plywood for the first base course and the application of a second course of P&S plywood over the base course, will provide a significant substrate for finished flooring. The second application of the plywood should be installed in the opposite direction as the first course to maximize strength.