Plywood is a common building material, found in most modern building projects. It is made from sheets of pressed veneer (thin sheets of wood). Plywood is strong, versatile, flexible and cheap — characteristics that make it a top choice for builders. The characteristics of plywood can be changed by using different bonding agents and grades of wood.
Plywood has high strength- and stiffness-to-weight ratios. One reason plywood is so strong is that it is made of many sheets, or veneers, of wood particles. The more layers, the stronger it is. Plywood is graded from A to D based on the quality of the face material. A higher graded plywood costs more money but also does the job better.
Because plywood doesn't shrink, crack or warp easily it can be used in climates with huge temperature and condition variations. Unprotected plywood molds and becomes damaged, so usually a protective layer of paint and top coat are placed on plywood.
Plywood is a versatile material. It can be nailed to edges easily and even though it is strong and made of many layers, it is easy to cut with proper equipment. Plywood is relatively lightweight and can be lifted by one or two people. It can be nailed or screwed into place, sanded or cut down to size. Plywood can also be glued into place. Working with plywood takes only basic carpentry skills.
Plywood comes in several different types for different applications. Medium density fiber core hardwood plywood is made from heat-pressed wood dust. This is a heavier type of plywood that is sometimes covered with a wood veneer. One drawback to this type of plywood is that it is heavier than other kinds. Medium and high density overlay plywood consists of a core, and then a pressed fiber material is laid over that core. This type has a lower weight than the medium density fiber core hardwood plywood but is also more stable than other types. CDX plywood is a common type used for construction. For example, it's commonly found in walls and roof sheathing.