OSB: Oriented Strand Board

OSB is an engineered building material commonly used as sheathing or sub-floor. Newer generations of the product are becoming less prone to delamination from water exposure. OSB is made from layers of wood strands that are roughly 6" long and 3/8" to 1/2" in width and are laid up in layers of a core layer and inner / outer face layers. These layers are laid up with their strands of wood "oriented" 90 degrees to each other (hence the name oriented strand board). The wood strands are coated with resin and pressed together using heat and pressure for a strong, stable and economical building material.