OSB Oriented Strand Board LSB Machine Production Line

Oriented strand board (OSB), also known as flakeboard, is a type of engineered lumber similar to particle board, formed by adding adhesives and then compressing layers of wood strands (flakes) in specific orientations. It was invented in California in 1963. OSB may have a rough and variegated surface with the individual strips of around 2.5 cm × 15 cm (1.0 by 5.9 inches), lying unevenly across each other and comes in a variety of types and thicknesses.

OSB is a material with favorable mechanical properties that make it particularly suitable for load-bearing applications in construction. It is now more popular than plywood, commanding 66% of the structural panel market. The most common uses are as sheathing in walls, flooring, and roof decking. For exterior wall applications, panels are available with a radiant-barrier layer pre-laminated to one side; this eases installation and increases energy performance of the building envelope. OSB also sees some use in furniture production.

Adjustments to the manufacturing process can impart differences in thickness, panel size, strength, and rigidity. OSB panels have no internal gaps or voids, and are water-resistant, although they do require additional membranes to achieve impermeability to water and are not recommended for exterior use. The finished product has properties similar to plywood, but is uniform and cheaper. When tested to failure, OSB has a greater load-bearing capacity than milled wood panels. It has replaced plywood in many environments, especially the North American structural panel market. Unfortunately, its use as sheathing has contributed to the leaky condo crisis, as it is less able to breathe and release moisture than plywood.