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The history of tiles will be investigated at first in order to know the origin and then thereafter to ascertain what the evolution of such building material is. Tiles were used for centuries and are a fundamental building material in modern construction in South Africa. For the purpose of this chapter the most emphasis or concentration will be placed upon roof tiling, there are an immense number of different tile selections to do research upon like floor tiling, wall tiling etc.
The majority of information gathered regarding this chapter was taken from Davey (1961)
2.2 The History of most common types of roof tiling
2.2.1 Stone Tiles
Flat roofs that were common in the Middle East and Egypt were difficult to keep weather tight in wet conditions. Pitched roofs were better utilised, because surfaces could be plastered or thatched to provide good run-off for rainwater. Provision of a suitable roof for the more permanent stone buildings were difficult enough although something more durable was needed and interlocking terracotta tiles were devised in the seventh century B.C. or maybe earlier, which could be fixed to low pitched roofs.
Stone roofing tiles were used by the Romans, some almost oval, others four-, five,- or six-sided, slightly rounded or pointed at their lower extremity. These stone tiles were hung by a single wooden peg upon the battens or nailed to them. The exposed bottom edges of the tiles, which sloped upwards at a 45Ëš angle, formed a diagonal reticulate pattern like shown if figure 2 below.
Figure 2: Romano - British stone roof. Source: Davey (1961)
Various types of sandstone and limestone were used. Local limestone and sandstone were used at Chedworth in Gloucestershire from the forest of Dean were ridge tiles and finials were carved from stone.
Stone roofing tiles continued to be used in Britain since the Roman times, where they have been made from various limestone's, sandstones and sedimentary rocks which split into slim slabs, 15mm to 25mm thick. These tiles could be trimmed to rectangular shapes and sizes, suitable for the use of roofing tiles.
The different sizes of stone tiles were not given by dimensions but were rather given by picturesque names that have come down through history: for example, long sixteen (58,42cm); short sixteen, long fifteen (54,61cm); short fifteen etc. These are only some picturesque names given, they embark from long sixteen through too long and short eleven (39,37cm), then names would change from long wivett to long bachelor, short bachelor, long beck, middle beck, short beck, muffity, long cutting, short cutting etc. each with its own specific size.
2.2.3 Slate Tiles
Slate tiles are defined as follow, where sedimentary argillaceous stone is produced by means of metamorphism of primary or igneous rocks. Forms of fine clay with volcanic dust or sand was deposited under water and consolidated by vertical pressure into mudstone and shale. In this condition sedimentary particles were cemented by carbonates of magnesia and lime, by kaolin or various iron compounds. Great lateral pressure and intense heat subsequently converted the product into slate.
This specific structure mentioned above provided great strength and elasticity to the material. Cleavage planes that are formed in the material do not necessarily coincide with, and may in fact even be oblique to the sedimentation beds formed during the deposition of original material. A block of slate can be split easily with a chisel or hammer along the cleavage planes, into a number of laminae. The thinner the laminae the better the durability and quality of the tile.
Documentary evidence show that English slate tiles have been used since the twelfth century A.D. Along the south coast as far as Kent there was a considerable trade in Cornish and Devonian roofing slates. These roofing slates were found at more than twenty-five medieval sites along the south coast of England and its hinterland. Devon and Cornwall are some of the oldest quarries found, particularly along the north coast near Delabole, but some of these quarries have long since been abandoned from that period. The colour of slates varied considerably in different areas and quarries. The colours ranged from green, blue, red, purple and grey with mixing colours of previously mentioned also occurred.
The various sizes of slate tiles are known by quaint names in very much the same way as stone tiles like mentioned above. The largest tiles were called Empresses that measured 66.04cm by 40.64cm, small Empresses measured at 66.04cm by 35.56cm etc. These are only some quaint names given, they embark from Empresses through too Princesses, Duchesses, Small Duchesses, Marchionesses, Wide Countesses, Countesses, Wide Viscountesses, Viscountesses, etc. each with its own specific size.
2.2.4 Terracotta and Clay Tiles
The earliest form of terracotta tiling was found in the ruins of the Temple of Hera, at Olympia 640 B.C. These tiles consisted of two elements, a wide tile called the tegula, either square or rectangular, more or less curved in section and a narrow semi-cylindrical tile called the imbrex that was usually tapered at one end to fit into a wider opening of the one adjoining it.
Older roofing tiles of the world grouped themselves into three distinctive types, which were called the normal type A, or Asiatic tile; the Belgic tile or pan, type B, which is an outgrowth of the normal type A tile; and the flat or Germanic tile, type C, which had its independent form, Figure 3.
Figure 3: The Classification of clay roofing tiles. Source: Davey (1961)
The earliest known form of tile, the normal tile covers by far the greater number of roofs. The principal form of tile was used in Greece, Asia, Asia Manor, Spain, Italy, Sicily, the countries bordering the southern shores of the Mediterranean, and all the Portuguese and Spanish colonies.
Figure 3 above shows the outlines of various terracotta roofing tiles that are indicated into specific groups. Group A are the oldest and are called normal (Asiatic) tiles. Group B the pan (Belgic), and then group C (Germanic). Type A1 with the curved tegula and semicircular imbrices is the oldest and occurs in the Orient, in Ancient Greece, in Italy it is called the Laconian type. Type A2 with the flat tegulae and semicircular imbrices, the Sicilian type, occurs in Italy, Greece, both Ancient and Modern. Type A3 with flat tegulae and imbrices of triangular cross-section, the Corinthian type, occurs in Ancient Greece. Type A4 with the curved tegulae and similarly shaped tiles as imbrices, is commonly found in India and China. Type A5 with semicircular imbrices and almost similarly shaped tegulae, occurs in the Mediterranean countries and in the Orient.
Type B1 in England and Scandinavia is the common pan tile, and Type B2 is that common in Holland, Belgium, Scandinavia, Java and Japan. Type B3 is reasonably modern and is now used in several countries.
Type C which observed is a flat tile and is common in Austria, Germany, Poland, England, France, Switzerland, Hungary, all countries which wooden shingles are still used.
Figure 4: Roman roofing tiles that are tapered and flat with different fixing methods.
Source: Davey (1961)
The above picture shows a tile that was marked; these markings or stamp indicated the mark of the marker from a state-owned tile factory. One such tile from the roof of Basilica at Silchester that is now in a Reading Museum, is a tegula upon which the surface is scratched with the name BIRGINVS.
A number of roof tiles have also been found that had dates marked on them. It is thought that these dates represent the dates on which the roof tiles were manufactured.
The ridges of Roman Roofs were capped with a semicircular tile cemented in position. Some unique ridge tiles were found in a Roman Kiln at Canterbury. These ridge tiles had slots cut into their lower edges, two slots a side, to fit perfectly over the two flanges of adjacent tegulae. These tiles had a lattice pattern incised on the upper surface, and the intention must have been to render them with mortar to seal the joints between the tiles to make them weather tight. A second layer of cement may have been applied to the ridge tiles upon the first layer to cover all the joints.
Figure 5: Roman clay ridge tile in a kiln at Canterbury. Source: Davey (1961)
2. 3 How did the use of tiles evolve?
This part of the chapter will focus more on clay roofing tiles as it will narrow down the research goal of this chapter. All of the above mentioned roofing tiles are also important but most emphasis will be placed on clay roofing tiles.
The Romans used clay tiles in England mentioned above (Tegula and Imbrex). After the departure of the Romans the art of making such clay tiles was lost, and only few monasteries continued to make clay tiles for their own purpose, a situation that continued until the 12th century.
At First the plain clay tiles were simple rectangles of clay with nibs pressed to them by hand, and then laid to overlap the joints of those beneath them. These tiles were generally 26.67cm by 15.24cm, which was a size that was convenient to manufacture and handle. King Edward IV in 1477 passed an Act of Parliament laying down their minimum size. Today plain clay tiles are standardised to 26.67cm by 15.24cm. In some places plain clay tiles were historically supplied in non-standardised sizes, for example in York many of the older buildings are still roofed with using 30.48cm by 17.78cm plain clay tiles.
In the 12th or 13th centuries, more general use of plain clay tiles seems to have commenced. In London in 1666 after the Great Fire, thatched roofing was no longer allowed and clay tiles obviously provided fireproof alternatives.
Overlapping tiles were re-introduced into Britain from the Netherlands in the 16th century. The Dutch discovered the idea of linking tiles together using an S-shape or ogee, rather than relying on vertical overlaps to prevent water from penetrating into the structures. This new design was effectively a Roman under and over, that was joined into one tile. Today's tillers still find it difficult to understand the concept of the way pan-tiles overlap. In order to make these tiles fit against each other from side to side, and from top to bottom. It was necessary to chamfer the top right and bottom left corners or shoulders of each tile, to make them fit easily.
Figure 6: Overlapping clay tiles.
These tiles became known as pan-tiles in England. The advantages of these pan-tiles over plain tiles were easily apparent. Plain tiles were laid with their side joints butted together, while pan-tiles actually overlapped each other from side to side. Water could easily penetrate through plain tiles, and 2 to 3 thicknesses of tiles were utilised to ensure that they were watertight. Pan-tiles on the other hand only required 1 to 2 thicknesses of tiles at any point to make the roof structure watertight. Because of this reasons we nowadays refer plain tiles as "double lap tiles", and we call overlap or interlocking tiles, "single lap tiles".
To construct a roof of using plain tiles you will need 60 tiles per square metre, but with using pan-tiles you will only need round about 15 tiles per square metre, saving in labour time, costs and weight.
Some time before pan-tiles were made in England, there were records of them being imported from the Netherlands. A trading link resulted from Flemish weavers settling in East Anglia. One of the first historical references to clay tiles were reported, Mr Daniel Defoe the author of Gulliver's Travels, became the proprietor of a factory on the Thames at Tilbury, in order to manufacture clay pan-tiles. The works of manufacturing clay tiles closed in 1703.
Another popular roofing material has always been popular alongside clay tiles, which was Natural Slate. In the mid 19th century slate began its appearance more widely outside native areas with development of railways. Instead of being used on expensive houses and public buildings, slate was used on mass housing, the evidence is still apparent in most inner city areas.
During the first half of the 20th century clay tile technology took a momentous step forward. As an alternative of using the simple overlapping ogee (an "S" laid on its side), tiles were designed with a raised weather bar. These tiles interlocked with each other, one tile to the next. Finished tiles that were twisted due to firing or drying faults still interlocked and were able to cope with adequate water. This allowed that architects could design lower pitched roofs and improve performance.
Courtrai tile and the Marseille shaped tile became well known in British roofing. Marseille roof tiles were patented in France in 1874. Marseille roof tiles were exported to America, New Zealand, Australia and England.
Abroad competition caused that the British clay pan tile industry to disappear in the 1950s with its inability to keep pace with the demand from booming housing industries. By the 1960s, architects believed that you could no longer obtain clay pan-tiles in Britain. Concrete tiles gained the upper hand at this time in Britain. When concrete tiles were first introduced into the UK in the 1920s they failed to become popular. After World War 2 a huge housing programme started were the demand rapidly took off.
Furthermore, in the 1960s concrete tiles appeared in a large format than hitherto. Sizes were much more regular and shaped than clay tiles therefore they were much more favoured by contractors, as being much easier to fix on the roof.
It was in the 1970s that the renaissance of clay tiles industries got under way. Brand new technology for computerised kiln firing and automated handling was developed. German machine pressing technology allowed clay tiles to be made more efficiently. Shapes of tiles became more regular, tiles could be made larger, cheaper and they did not suffer from frost problems. The supply of tiles is more reliable since they no longer were dried in open sheds at the mercy of winter frost.
In France, Germany and Spain, all these developments took place during the 70s and the 80s, where concrete tiles continued to dominate the roofing scene.
From the 1970s there was a slow but steady recovery in clay and slate tiles, but the dominance of concrete tiles were challenged for the first time. Early in this century investments in modern and efficient new clay tile factories led to the introduction of an array of innovative new products that made clay tiles more affordable especially against concrete tiles.
2.4 Summary and Conclusion
An array of different types of tiles was used in different date and era's and by different nations. Roofing tiles have been manufactured and produced in many different sizes and shapes for different reasons and uses. The rectangular shaped tile has always been the dominant shape used by cultures and communities. Colours changed drastically. The names in the modern era definitely changed since the starting use of tiles with different names and stamps that were given to them, but the basic idea of giving these tiles names and putting stamps on them are still performed today.
2.5 Hypothesis Test
In chapter one, the hypothesis stated that the earliest tiles were used for flooring, roof covering and aesthetical purposes with different techniques and methods applied to the tiles and that they were used for the first time in Eastern Countries like India, France, Spain and China.
The main focus of the hypothesis ended up being the history of clay tiles were other tiles were not focused upon in such depth.
The hypothesis has been proven to be correct in part only. Tiles were discovered in the Eastern Countries like France, China and Spain, with the Romans to be the first to have used tiles. The earliest form of terracotta tiling was found in the ruins of the Temple of Hera, at Olympia 640 B.C. Countries like Greece and England in the UK also used tiles. The aesthetic appeal and tiling for floors were not covered in this chapter.