Plywood is itself a basic form of composite, created by laminating thin sheets of wood together to create a thicker, stronger final product. The quality and durability of plywood depends on both the timber species and the adhesive used to bond it. Plywood also comes in decorative finishes. Common applications of plywood are found in roof sheathing, siding, floor underlayment and structural diaphragms. Plywood grading is carried out according to the appearance and finish of the exposed (face and back) faces and it varies from country to country. Types of plywood :