Roof tiles

Roofs with "beaver tail" tiles inDinkelsbühl, Germany.

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:

Flat 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 are 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.

Interlocking roof tiles are similar to pantile with side and top locking to improve protection from water

and wind.

File:Gebr.Laumans-rooftiles.jpg

Gebr.Laumans-rooftiles

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.

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.[1]

[edit]History

Ancient Greek roof tiles

Roof fragment of Roman bath in Bath, Somerset, England

Roman roof tile fragment (78mm wide by 97mm high) found in York, UK, with the impression of a kitten's paw.

Fired roof tiles are found as early as the 3rd millennium BC in the Early Helladic House of the

tilesin Lerna, Greece.[2] [3] Debris found at the site contained thousands of terracotta tiles having fallen

from the roof.[4] In the Mycenaean period, roofs tiles are documented for Gla and Midea.[5]

The earliest finds of roof tiles in archaic Greece are documented from a very restricted area

aroundCorinth (Greece), where fired tiles began to replace thatched roofs at two temples

of Apollo andPoseidon between 700-650 BC.[6] Spreading rapidly, roof tiles were within fifty years in

evidence for a large number of sites around the Eastern Mediterranean, including Mainland Greece,

WesternAsia Minor, Southern and Central Italy.[7] Early roof tiles showed an S-shape, with the pan and

cover tile forming one piece. They were rather bulky affairs, weighing around 30 kg apiece.[8] Being more

expensive and labour-intensive to produce than thatch, their introduction has been explained by their

greatly enhanced fire resistance which gave desired protection to the costly temples.[9]

The spread of the roof tile technique has to be viewed in connection with the simultaneous rise of

monumental architecture in ancient Greece. Only the appearing stone walls, which were replacing the

earlier mudbrick and wood walls, were strong enough to support the weight of a tiled roof.[10] As a side-

effect, it has been assumed that the new stone and tile construction also ushered in the end of 'Chinese

roof' (Knickdach) construction in Greek architecture, as they made the need for an extended roof as rain

protection for the mudbrick walls obsolete.[11]

The production of dutch roof tiles started in the 14th century when city management required the use fire

proof materials. At that time most houses were made of wood and had straw roofing and a fire could burn

down the whole city. To satisfy demand, many small roof tile makers began to produce roof tiles by hand.

Many of these small factories set up production near rivers both for the availability of clay as well as ease

of transport.