Oriented strand board
From Wikipedia, the free encyclopedia
Oriented strand board, or OSB, is an engineered wood product formed by layering strands (flakes) of wood in specific orientations. In appearance it has a rough and variegated surface with the individual strips (around 2.5 by 15 cm each) lying unevenly across each other in the direction of their grain.
It is manufactured in wide mats from cross-oriented layers of thin, rectangular wooden strips compressed and bonded together with wax and resin adhesives (95% wood, 5% wax and resin). The layers are created by shredding the wood into the strips, these are sifted and then oriented on a belt. The mat is made in a forming bed, the layers are built up with the external layers aligned in the panel direction and internal layers randomly positioned. The number of layers placed is determined by the thickness of the finished panel. Typically a 15 cm layer will produce a 15 mm panel thickness. The mat is then placed in a thermal press. Individual panels are then cut from the mats in standard sizes.
Different qualities in terms of thickness, panel size, strength, and rigidity can be imparted to the OSB by changes in the manufacturing process. OSB panels have no internal gaps or voids, and are water-resistant, although they do require additional membranes to achieve impermeability to water. The finished product has similar properties to plywood, but is uniform and cheaper. It has begun to replace plywood in many environments. The most common uses are as sheathing in walls, floors, and roofs.
While OSB does not have grain like a natural wood, it does have a specific axis of strength. This can be seen by observing the alignment of the surface wood chips. The most accurate method for determining the axis of strength is to examine the ink stamps placed on the wood by the manufacturer.
There is some debate over the environmental impact of OSB. It allows producers to use tree species such as aspen or poplar that are unfit for standard veneer plywood or lumber. The production method uses almost all the wood of the harvested trees, and small, young trees and lower quality fast growing species can be used. Due to the type of resins used in wood-based structural use panels like OSB, they emit very low levels of Formaldehyde. The emission levels have been found to be not more than 10% of the criteria of key national standards.
All wood-based structural use panels can be cut and installed with the same ease and types of equipment used with solid wood. In 2001, 19.4 million m³ of OSB panel was produced in the US. The US is Canada's largest OSB market, receiving 98% of its export product in 2005.Review of Canadian Structural Panel Market
OSB is commonly known as Sterling board in the United Kingdom.
