Plywood is constructed of odd number of wood veneer plies glued together and cross-bonded. Such construction provides stability, strength and high resistance to vibrations and shocks, warping and splitting. Plywood is manufactured of various wood species. For the production of European plywood are mostly used beech, birch, spruce, poplar. Birch plywood has fully birch plies. Plywood birch/alder has birch face layers in high grades and birch or alder in low grades. The core is birch/alder combined.
Plywood is divided in interior and exterior depending upon the water resistance of the used glue which is indicated by code letters on each sheet. Plywood interior and plywood exterior may be made of hardwood or softwood, both consist of three and more glued layers. The method of construction distinguishes plywood interior and plywood exterior. Plywood interior glued will be delaminated by water as the layers will come apart. Exterior plywood immersed in boiling water for 24-72 hours will not be delaminated.
Exterior plywood costs more than interior and may be used inside and outside as the glue allows this usage. Interior plywood can be used anywhere inside.
Birch plywood is used as a structural material, as well as a ready component. The examples of products made of plywood are packing boxes, wind blades, furniture, floors, panels, sport equipment, musical instruments, etc.