A tile is a manufactured piece of hard-wearing material such as ceramic, stone, metal, or even glass. Tiles are generally used for covering roofs, floors, and walls, or other objects such as tabletops. Another category are the ceiling tiles, made from lightweight materials such as perlite, wood, and mineral wool. The word is derived from the French word tuile, which is, in turn, from the Latin word tegula, meaning a roof tile composed of baked clay. Less precisely, the modern term can refer to any sort of construction tile or similar object, such as rectangular counters used in playing games (see tile-based game).
Tiles are often used to form wall and floor coverings, and can range from simple square tiles to complex mosaics. Tiles are most often made from ceramic, with a hard glaze finish, but other materials are also commonly used, such as glass, marble, granite, slate, and reformed ceramic slurry, which is cast in a mould and fired.
In the past twenty years, the technology surrounding porcelain tile and glass tiles has become more efficient, allowing more mass production. Similarly, the invention of automated tile lines that use diamonds to cut and finish stone slabs into tiles has made stone tiles more available. This has allowed these tiles to move from being niche items into broader markets. The DSAN U.S. Ceramic Tile Demand Index has shown a growth of 5.0% annually for the 2000-2006 period, compared to 5.5% annually for the 2000-2005 period. The DSAN World Demand for (finished) Granite Index has shown a growth of 15% annually for the 2000-2006 period, compared to 14% annually for the 2000-2005 period, The DSAN World Demand for (finished) Marble Index has shown a growth of 12% annually for the 2000-2006 period, compared to 10.5% annually for the 2000-2005 period. The U.S. market for ceramic tile is over $3 billion.
Accompanying the growth in tile demand has been some shifts in the world ceramic tile industry. In 1990, Europe accounted for 54% of world ceramic tile production. By 2002, Europe was down to 25% of world ceramic tile production. In 2005, world ceramic tile production was about 7 billion sq. meters, of which China produced 35%, and Spain, Italy, and Brazil shared the next 25%, with their productions spaced neck and neck. Except for Spain, European ceramic tile production in the same period has dropped a little absolutely. Asia now has state-of-the-art equipment in its ceramic tile plants, which means much lower costs. The Europeans still do well with higher-priced ceramic tile with sophisticated and fashionable designs, and with porcellanato (high-quality porcelain) tiles. Beginning in 2004, the stronger Euro made it much cheaper to manufacture ceramic tile in the U.S. and distribute them from such a plant. The U.S. is the world's largest market for ceramic tile. A number of European (mostly Italian) ceramic tile manufacturers built or expanded their U.S. plants, or bought out domestic ceramic tile firms. The European tile firms not only benefitted from lower manufacturing costs but also from distributing at a lower cost and faster; of course, less inventory was required.
Things have been different in the dimension stone tile industry. By the beginning of the 1980s, automated stone tile plants were busy in Italy, the world leader that had close to a monopoly. The plants were not quite equivalent to those today, since additional innovations have crept in. Italy is now one among many; China has many plants with automated stone tile lines, as does Spain, Turkey, Brazil, and other countries. The three U.S. automated tile lines that were short-time producers of granite tile from the mid1980s to the mid1990s closed one by one; the last one actually closed in mid2002. Marble tile is still produced to a limited extent, but most American marble tile comes from tile plants in Carrara, Italy that make it from rough blocks of Vermont (Danby) marble. The amount of slate flooring tile has dwindled a little since 2000.
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:
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.
Fired roof tiles are found as early as the 3rd millennium BC in the Early Helladic House of the tiles in Lerna, Greece. Debris found at the site contained thousands of terracotta tiles having fallen from the roof. In the Mycenaean period, roofs tiles are documented for Gla and Midea.
The earliest finds of roof tiles in archaic Greece are documented from a very restricted area around Corinth (Greece), where fired tiles began to replace thatched roofs at two temples of Apollo and Poseidon between 700-650 BC. Spreading rapidly, roof tiles were within fifty years in evidence for a large number of sites around the Eastern Mediterranean, including Mainland Greece, Western Asia Minor, Southern and Central Italy. 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. Being more expensive and labour-intensive to produce than thatchet, their introduction has been explained by their greatly enhanced fire resistance which gave desired protection to the costly temples.
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. 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.
These are commonly made of ceramic or stone, although recent technological advances have resulted in glass tiles for floors as well. Ceramic tiles may be painted and glazed. Small mosaic tiles may be laid in various patterns. Floor tiles are typically set into mortar consisting of sand, cement and often a latex additive for extra adhesion. The spaces between the tiles are nowadays filled with sanded or unsanded floor grout, but traditionally mortar was used.
Natural stone tiles can be beautiful but as a natural product they are less uniform in color and pattern, and require more planning for use and installation. Mass produced stone tiles are uniform in width and length. Granite or marble tiles are sawn on both sides and then polished or finished on the facing up side, so that they have a uniform thickness. Other natural stone tiles such as slate are typically "riven" (split) on the facing up side so that the thickness of the tile varies slightly from one spot on the tile to another and from one tile to another. Variations in tile thickness can be handled by adjusting the amount of mortar under each part of the tile, by using wide grout lines that "ramp" between different thicknesses, or by using a cold chisel to knock off high spots.
Some stone tiles such as polished granite and marble are very slippery when wet. Stone tiles with a riven (split) surface such as slate or with a sawn and then sandblasted or honed surface will be more slip resistant. Ceramic tile for use in wet areas can be made more slip resistant either by using very small tiles so that the grout lines acts as grooves or by imprinting a contour pattern onto the face of the tile.
The hardness of natural stone tiles varies such that some of the softer stone (e.g. limestone) tiles are not suitable for very heavy traffic floor areas. On the other hand, ceramic tiles typically have a glazed upper surface and when that become scratched or pitted the floor looks worn, whereas the same amount of wear on natural stone tiles won't show, or will be less noticeable.
Natural stone tiles can be stained by spilled liquids; they must be sealed and periodically resealed with a sealant in contrast to ceramic tiles which only need their grout lines sealed. However, because of the complex, non repeating patterns in natural stone, small amounts of dirt on many natural stone floor tiles do not show.
Most vendors of stone tiles emphasize that there will be variation in color and pattern from one batch of tiles to another of the same description and variation within the same batch.
Stone floor tiles tend to be heavier than ceramic tiles and somewhat more prone to breakage during shipment.
Although decorative tilework was known and extensively practiced in the ancient world (as evidenced in the magnificent mosaics of Pompeii and Herculaneum), it perhaps reached its greatest expression during the Islamic period. Perhaps because of the tenets of Muslim "sharia" law, which disavow religious icons and images in favor of more abstract and universal representations of the divine, many consider decorative tilework to have reached a pinnacle of expression and detail during the Islamic period. Palaces, public buildings, and mosques were heavily decorated with dense, often massive mosaics and friezes of astonishing complexity. As both the influence and the extent of Islam spread during the Middle Ages this artistic tradition was carried along, finding expression from the gardens and courtyards of Málaga in Moorish Spain to the mosaics of the Hagia Sophia in Constantinople.