Oriented strand board (OSB) is an engineered structural panel composed of strands of wood cut from small logs. It is used primarily as a load-bearing component in platform-frame–constructed buildings such as single-family and multi-family housing. It is used in wall sheathing, flooring and roofing applications. It is also used as a component in the manufacture of other products, including furniture and engineered wood products.
OSB is composed of wood strands bonded under heat and pressure with waterproof glues. It is produced with the strands in the surface layers aligned in the direction of the long axis of the panel and with the strands in the inner layer either cross-aligned or randomly oriented. This orientation of strands gives the panel sufficient strength for its structural applications when it is positioned appropriately.
OSB is produced in thicknesses ranging from ¼ inch to 2½ inches; the most commonly used thicknesses are ⅜, ½ and ⅝ inch. Larger panels (commonly 8x24 feet) are subsequently cut to 4x8 feet panels for retail. OSB panels may be square edged or tongue-and-grooved to aid in the connection of adjacent panels on site. OSB has particularly good nail-holding properties and can be glued with regular wood adhesives.
For the past 25 years in North America, and more recently in Europe, OSB has been steadily replacing plywood as a structural panel in construction and packaging. While OSB is less costly to produce than plywood, it is heavier and is less tolerant of moisture. It is already widely used as wall sheathing, roof sheathing and packaging material for shipping containers. More recently, technology has enabled the use of OSB for subflooring, furniture frames and pre-fabricated house components. It is also used in engineered wood products such as I-joists and I-beams.
Between 1990 and 2005, OSB production in Canada and the U.S. expanded dramatically in regions where large quantities of aspen and other underutilized species of wood were available. However, the downturn in the U.S. housing sector that began in 2006 resulted in the closure of many operations, which only began to reopen in 2013.
In 2012, Canada produced one-third of North American OSB—5.2 million cubic metres out of a total of 15.1 cubic metres. Since OSB production plants are very large and are designed to produce continuously, it will take several years for the remaining idle capacity to return to production. As a result, no new North American mills are currently expected to be built.
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