RIBA Core Curriculum
- Building conservation and heritage
- Design, construction and technology
- General Awareness
Clay is a highly versatile and durable construction component that alongside stone and wood, is one of the oldest and most influential building materials on earth. This course looks at the history of clay in roofing and how this impacted and shaped modern roof tiles. The manufacturing process, roofing legislation and the different types and formats of clay tiles are also considered.
In this section
- The history of clay roofing
- Cultural influences on roof tile design
- The roots of modern roofing
Why use clay?
Used for thousands of years in construction worldwide, clay remains the most efficient, cost effective and sustainable solution for modern buildings.
Clay is strong, durable and builds in sound and temperature control benefits. Its natural properties mean that it is able to provide complete, long term sustainability, giving a building life of hundreds of years with little or no maintenance.
Which civilisation was the first to use clay as a building product? The Egyptians, Greeks and Romans are all amongst the early cultures to have utilised clay.
However, history suggests that the first use was in the alluvial plains between Tigris and Euphrates in ancient Mesopotamia, which would be modern day Iraq.
Mesopotamia is one of the earliest known developments of the Neolithic or Agricultural Revolution from around 10,000 BC, when there was a wide-scale transition of many human cultures from a lifestyle of hunting and gathering to one of agriculture and settlement.
The transition to agriculture and settlements made it possible to sustain increasingly larger populations, which had a profound impact on creativity and invention.
The Mesopotamians inspired some of the most important developments in human history including the invention of the wheel, cursive script, mathematics, astronomy, agriculture, beer and clay bricks.
Clay bricks were produced in vast quantities to build great cities and complex structures.
Ziggurats were massive structures, with a terraced compound of successively receding stories or levels, which included a temple complex as well as other buildings.
The Ziggurats were thought to be cosmic mountains or ladders to heaven with the temples presiding at top to be nearer to the gods. These structures also provided a good vantage points and look outs for generals, making it easier to defend against enemy attacks.
Djenne (pronounced Jenna) Mosque in Mali, West Africa is one of the world’s largest mud-brick structures and is a great example of this style of ancient building. The site requires constant maintenance and is resurfaced every year after the seasonal rains, in a ceremony that involves the local community.
The wooden posts adorning the sides enable workers to climb up the massive building during the restoration process.
What led to the use of clay as a roofing material?
Who made the first roof tiles?
There are various claims throughout history for where the first roof tile originated, but probably the most reputable of these is Historia Naturalis (Natural History) written in AD77 by Gaius Plinius Secundus, better known as Pliny The Elder.
Pliny’s Natural History was a magnificent encyclopaedia that recorded all known sciences, it included 37 books, organised into ten volumes and covered a huge range of subjects. It was also the precursor to modern encyclopedias.
The history of the first tiles is intertwined with the the tale of Agrippa, who was a Roman General and school friend of Octavia. Octavia went on to become Emperor Augustus and together with Agrippa they conquered, united and ransacked foreign countries to establish the Roman Empire.
Agrippa then succeeded Augustus as Emperor and transformed Rome into a city of marble, building the Pantheon, the port of Misenum and numerous fantastic aqueducts.
However according to Pliny’s Natural History, it was Agrippa’s son, Herod Agrippa II, that was responsible for the production of the first tiles, which were constructed in marble and stone.
The origins of plain tiles came initially from large leaves which were found in jungle, forest and woodland areas, these were used overlapped on simple roof structures to keep out the rain.
The next stage in the evolution of roofing was the change from leaves to using split pieces of timer (shingles). There was then a move from wooden shingles towards more robust durable tiles which led to the types plain tiles which we are familiar with today.
This was a very straightforward linear development.
The evolution of profiled tiles followed two different but similar routes to that of plain tiles.
Tegula and Imbrex
Tegula and Imbrex uses a flat plate undertile laid butted together (Tegula) with a tapered roll tile (Imbrex) bedded onto the joints. This became widely known as the Roman tile – despite being of Greek descent.
Under and Over Tile
Under and Over Tiles use the same principles as the Tegula and Imbrex but are curved in their profile. This style of tiles became associated with the Spanish and so became recognised as Spanish tiles, which evolved later into the modern familiar pantile shape. Examples of this popular type of roof can be found across various Mediterranean countries.
How and where were the first clay roof tiles made?
The previous pictures are contemporary but illustrate the the traditional manufacturing technique.
There is a popular myth that traditionally tiles were formed over a suitable shape, such as a female thigh, although the previous images show a shaped form.
Early Chinese records suggest roof tiles were being produced there in BC 2700, roughly the same time as the Mesopotamians. If true, this surpasses the claims of both the Romans and the Greeks.
The tiles in the previous image are similar to Tegula and Imbrex shapes developed by the Greeks, which later become popular with the Romans.
The Greeks may have not been first to produce tiles, but evidence suggest that they were the first to understand the firing process which greatly improved durability. The earliest fired clay roof tiles that have been identified are plain tiles from Lerna in Greece, dating back to about BC 1800. Lerna tiles were approximately 175mm long and similar to today’s plain tile.
The Stoa of Athens built in 150BC, was a commercial centre commissioned by King of Pergammon as gift to Athens. It was roofed with clay tiles.
This previous image shows the modern reconstruction of this building, which used a replica of the original Greek Tegula and Imbrex tile. The tiles were re-created for this project when the Stoa was re-built from excavated ruins in 1956.
This tile is in two parts, an underside (Tegula) and a smaller covering tile (Imbrex).
The Romans were the first to make clay tiles in Britain, at the time it was believed that they had pioneered the use of them.
The tiles the Roman’s produced in Britain were similar to Greek tiles we’ve previously seen.
The Spanish tile is completely tapered and used “under” and “over” as the name suggests.
It is exactly the same principle as Greek Tegula and Imbrex tile but it is curved. The different styles of tiles influenced architecture in Britain and caused a blurring of the differences between Greek, Roman and Spanish tiles.
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