Oriented strandboard (OSB) are panel products which illustrate the trend toward more efficient use of forest resources, while employing less valuable, fast-growing species. At the same time, they provide economy of construction and substantial insulation and structural advantages.
OSB are panel products made of aspen or poplar (as well as southern yellow pine in the US) strands which are bonded together under heat and pressure using a waterproof phenolic resin adhesive or equivalent waterproof binder.
The strands in the outer faces of OSB are oriented along the long axis of the panel thereby, like plywood, making it stronger along the long axis as compared to the narrow axis. The strands in inner layers are oriented either perpendicular to the longitudinal axis or randomly. This results in a structural engineered wood panel with improved stiffness and strength properties and dimensional stability.
The strands used in the manufacture of OSB are generally up to 150 mm (6”) long in the grain direction and 25 mm (1″) wide and less than 1 mm (1/32″) in thickness.
In Canada, OSB panels are manufactured to meet the requirements of Canadian Standards Association (CSA) standard CSA O325, Construction Sheathing. In the US, U.S. Department of Commerce/National Institute of Standards and Technology Voluntary Product Standard PS 2, Performance Standard for Wood-Based Structural-Use Panels, must be met.
OSB panels are used in construction mainly as roof, wall and floor sheathing, and are accepted for structural purposes in diaphragm and shearwall applications. Some specialty products are made for siding and for concrete formwork.
OSB is also used as the web material for some types of prefabricated wood I-joists, and skin material for structural insulated panels.