Concrete / Clay tiles
Roof tiles are designed mainly to keep out rain, and are traditionally made from locally available materials such as terracotta 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:
- Interlocking roof tiles – tiles with side and top locking to improve protection from water and wind.
- Flat / plain tiles – the simplest type, which are laid in regular overlapping rows. An example of this is the clay-made “beaver-tail” tile (GermanBiberschwanz), common in Southern Germany. Flat roof tiles are usually made of clay but also may be made of stone, wood, plastic, concrete, or solar cells.
- Imbrex and tegula – an ancient Roman pattern of curved and flat tiles that make rain channels on a roof.
- Roman tiles – flat in the middle, with a concave curve at one end at a convex curve at the other, to allow interlocking.
- Pantiles – with an S-shaped profile, allowing adjacent tiles to interlock. These result in a ridged pattern resembling a ploughed field. An example of this is the “double Roman” tile, dating from the late 19th century in England and USA.
- Mission or barrel tiles – semi-cylindrical tiles laid in alternating columns of convex and concave tiles. Originally they were made by forming clay around a curved surface, often a log or the maker’s thigh. Today barrel tiles are mass-produced from clay, metal, concrete or plastic.
- Roof tiles are ‘hung’ from the framework of a roof by fixing them with nails. The tiles are usually hung in parallel rows, with each row overlapping the row below it to exclude rainwater and to cover the nails that hold the row below. There are also roof tiles for special positions, particularly where the planes of the several pitches meet. They include ridge, hip and valley tiles. These can either be bedded and pointed in cement mortar or mechanically fixed.
Similarly to roof tiling, tiling has been used to provide a protective weather envelope to the sides of timber frame buildings. These are hung on laths nailed to wall timbers, with tiles specially moulded to cover corners and jambs. Often these tiles are shaped at the exposed end to give a decorative effect. Another form of this is the so-called mathematical tile, which was hung on laths, nailed and then grouted. This form of tiling gives an imitation of brickwork and was developed to give the appearance of brick, but avoided the brick taxes of the 18th century.