Plywood is used as sheathing that contacts concrete for job-built forms and prefabricated form panels. Since plywood comes in large sizes, it saves forming time. Plywood is made by gluing together thin layers of wood, called veneer, under intense heat and pressure. Most plywood panels are made of softwood. Many species of trees are used to make plywood, such as Douglas fir and Southern pine. The grain of each ply is laid at a right angle to the adjacent pieces. This process gives plywood extra strength and reduces shrinkage and swelling.
Plywood is commonly sold in large sheets 4 X 8 ft (1.22 X 2.44 m). These large panels reduce erection and stripping costs and produce fewer joints on the finished concrete. Plywood is available in varieties of thicknesses that identify it for sale. For example, plywood called “V2 in. (12.7 mm) plywood’’ is 1/2 in. (12.7 mm) thick. In contrast to the situation with lumber, actual and nominal thickness for plywood is the same; 1 in. (25.4 mm) plywood is 1 full inch (25.4 mm) thick.