Oriented Strand Board (OSB)

Oriented Strand Board (OSB) is an engineered wood-based panel in which long strands of wood are bonded together with a synthetic resin adhesive. OSB is usually composed of three layers, strands in the mat are aligned either in each of the three layers of the panel or, more frequently, in only the outer two layers. The timbers used in OSB manufacture are typically softwoods (spruce, pine) but some hardwood (aspen) can be found in some brands (North America). Wood strands are cut tangentially from debarked logs which are held longitudinally against rotating knives. After drying, these flakes are generally sprayed with a synthetic resin binder and wax prior to the mat being pressed.

OSB varies in colour from a light straw colour to a medium brown depending on species used, resin system adopted and pressing conditions employed. OSB is readily identified by its larger and longer wood strands, compared to particleboard.

Because of its lay-up and composition, OSB is primarily a panel for construction and is widely used for flooring, flat roof decking and wall sheathing. Different grades of the product are available for different levels of loading and different environmental conditions.