- The material forming the contact face of forms. Also called lagging or sheeting.
- plywood, waferboard, oriented strand board, or lumber used to close up side walls, floors, or roofs preparatory to the installation of finish materials on the surface. The sheathing grades of lumber are also commonly used for pallets, crates, and certain industrial products.
- The first covering of exterior studs or rafters by boards, plywood, or particleboard.