Roof tile production is the industrial process in which raw materials — usually clay or concrete — are processed into finished roof tiles suitable for use on pitched roofs. The process includes extraction, preparation, shaping, firing or curing and finishing, and has been heavily mechanised over the past century and a half.
Production of ceramic (clay) tiles
The production of ceramic roof tiles takes place in several steps:
- Clay extraction — fatty river clay is mined and mixed with leaner clay and additives for the right plasticity
- Preparation — the clay is ground, sieved and homogenised in mixing tanks
- Shaping — the clay is pressed into tiles by a forming press, often in plaster or steel moulds
- Drying — tiles dry for 24-72 hours in a drying tunnel to prevent cracking during firing
- Firing — tiles are fired in a tunnel kiln at 1,000-1,150 °C, making them hard and water-shedding
- Finishing — engobe (a clay slip) or glaze can be applied for colour and gloss
Production of concrete tiles
Concrete tiles are extruded: a mixture of sand, cement, water and pigment is pressed onto steel plates. The tiles then cure in a curing chamber at elevated temperature and humidity. After curing, tiles are stacked and may receive a coating against moss growth.
Modern developments
- Automation — robots now handle stacking and sorting
- Engobes and glazes — colour and surface treatments improve durability
- Reduced raw-material consumption — thinner-pressed tiles, recycling of breakage
- Integrated photovoltaic tiles — tiles with built-in solar cells
Application
The choice between clay and concrete tiles depends on budget, aesthetics and building physics. Ceramic tiles patinate beautifully and often last more than 100 years; concrete tiles are cheaper but more susceptible to moss growth and fading.
Related terms
- History of roof tiles
- Roof tiles
- Pantile
- Engobe
- Glaze
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