What is a Clay Tile?
Clay tiles are produced by baking molded clay. The density of the clay is determined by the length of time and temperature at which it is heated. Colors of clay tiles range from shades of white, yellow, orange and brown.
The most commonly used clay color is the Terra-Cotta. Another alternative to these natural earth tones is to add enamels to the tile and make any color of roof tiles. This process is called “ceramic” and consists of spraying enamel over the tile before baking it.
High temperatures of the kiln permanently bond this color to the clay tile so it will not peel or fade. As a result there are a wide variety of tile profiles, styles, finishes and colors available. Because clay tiles are made from a natural earth derived material, they are environmentally friendly and easily recycled.
Clay tiles are resistant to strong winds and cannot be destroyed in a fire. Because of the way they are shaped, clay tiles protect the underlayment of your roof, while also creating an air pocket thereby helping to insulate and isolate any unwanted heat or cold from being transferred to your home’s attic space.
What is a Concrete Tile?
Concrete tiles are made of mixture of sand, cement and water, which are molded under heat and high pressure. The exposed surface of a tile may be finished with a paint like material.
Concrete tiles have additional water locks, or interlocking ribs on the edges that prevent water infiltration. Concrete tiles come in three main appearances: 1. Flat profile – no curves. 2. Low Profile – small curves and has a rise to width ratio equal to 1:5 or less. 3. High Profile: large curves and has a rise to width ratio greater than 1:5.
Concrete tiles can simulate the appearance of traditional clay tiles, wood shake, slate and stone. Like clay, concrete tile surfaces can be textured or smooth, and tile edges can be ragged or uniform. They are resistant to hail, wind, and fire, making them a very safe roofing material when properly installed.
What are the primary differences between Concrete and Clay tiles?
1. Water Absorption
Concrete roofing tiles have a water absorption of about 13%, while clay roofing tiles have a water absorption of about 6 %. Consequently, this higher rate of water absorption leads to the development of mildew and stains on concrete tiles.
Absorbed water also increases the already heavy weight of a concrete tile, and puts increases pressure on the roof structure. These issues are very minimal in clay tiles due to their low water absorption rate.
Concrete tiles weigh almost 40% more than clay tiles. Concrete tiles can weigh anywhere from 820 to 1.100 pounds per square (100 sq. ft.), depending on the style, while most clay roofing tiles weigh only 600 – 650 pounds per square. As a result, it is more difficult for the roof structure to adequately support the heavier weight of concrete tiles vs. clay tiles.
In some cases, concrete tiles are not recommended for use on buildings, unless the roof framing is reinforced to support the added weight.
Propensity to crack and shatter
In colder climates, clay tiles have a tendency to crack or shatter due to freezing and thawing cycles. As a result, clay tiles are mostly found in warmer climates.
Conversely, concrete tiles are not as susceptible to damage due to freezing temperatures, and therefore can be used in almost any climate.
Heavier weight, higher rate of water absorption and formation of mildew makes concrete tiles a lot more challenging to maintain than clay tiles, which are almost free of these issues.
For example, on ceramic finishes in Matte and Glazed clay tiles, absorption and mildew rates are almost non existent. This means that a clay roof would be practically maintenance free.
4. Color Longevity and Appearance
Since clay is a naturally occurring material, clay tiles maintain their original color for years despite being subjected to weather conditions.
Ceramic finishes offered by many clay roof tile manufacturers, are baked in high temperatures of around 2000 degrees, creating a non-porous finish that will virtually last forever.
On the other hand, the color-thru technology used in concrete tiles is not as effective in maintaining the original bright tile color, and concrete tiles are known to fade over time.
Due to its porous nature, concrete tiles are also more prone to stains than clay tiles.
While both concrete and clay tiles outperform most other roofing materials in durability, at the end of the day clay is a more durable material than concrete. Concrete tiles may last between 30 to 50 years, while clay tiles may well last over 100 years.
You can still see beautiful clay roofs on many buildings in Europe, which have been there for centuries.