Polyurethane binders are used to adhere numerous types of particles and fibers to each other. Their primary areas of use are in the manufacturing of wood panels, rubber or elastomeric flooring surfaces and sand casting for the foundry industry. The highest volume application for polyurethane binders is in the manufacture of Oriented Strand Board (OSB). These wood panels are used in structural sheathing and flooring, manufactured housing, joists and beams and shop panels. Rebond carpet underlay uses polyurethane binders to adhere scrap pieces of foam, which are often flexible polyurethane foam, together in its production.