Exterior walls composed of asbestos-free fiber and Portland cement combined under pressure. Typically, the natural siding or shingle is light gray. Board or shingle siding may be applied over sheathing or a building paper attached to either wood or steel stud framing. Sheet siding can be found with two basic profiles, either ribbed or corrugated, or as a sandwich panel attached to a structural frame. For greater accuracy, use component 118 (Cement Fiber Siding) for siding or shingles, or 119 (Cement Fiber Sheet) for sheet siding.