Roof shingles are a roof covering consisting of individual overlapping elements. These elements are normally flat rectangular shapes that are laid in rows without the side edges overlapping, a single layer is used to ensure a water-resistant result. Shingles are laid from the bottom edge of the roof up, with the bottom edge of each row overlapping the previous row by about one third its length. Fiberglass-based asphalt shingles are by far the most common roofing material used for residential roofing applications.
Roof tiles are designed mainly to keep out rain, and are traditionally made from locally available materials such as clay or slate. Modern materials such as concrete and plastic are also used and some clay tiles have a waterproof glaze. A large number of shapes (or “profiles”) of roof tiles have evolved. These include: