Clay Tile

Advantages to clay tile

• Long-lasting: A tile roof can last over 100 years, especially when installed in the right climate. Clay and concrete tile roofs have been known to withstand hail, high winds, and even fire. Once you install tile, you will never have to install another type of roofing again. Just in case, most manufacturers will offer a 50-year warranty.
• Impervious to rot and insect damage: Unlike wood, tiles roofs will never decay. 
• Environmentally friendly material: Tile roofs are made from earth minerals, not chemicals, and they can be pulverized and recycled when they are removed. 
• Energy efficient: The heavy thermal mass of tiles will help regulate indoor temperatures. 
• Low maintenance: Leaks are almost unheard of, and it is very rare for tile roofs to require repairs or maintenance unless they break due to heavy impact.
• Plenty of choices: Clay, concrete, and slate tiles come in a wide variety of colors and styles to match any home style, from Medieval to Contemporary European. Some styles even resemble traditional shingles or wood shakes. 

Disadvantages to clay tile

• High cost: A clay tile roof system can cost two to three times as much as an asphalt roofing system. An average clay tile roof costs between $675 to $1400 per square (100 SF of roof area). Concrete tile roofs are more economical, with costs of $400 to $450 per square. This is offset, though, by the long life a tile roof will enjoy. Slate tiles are by far the most expensive, with average costs running between $1,000 and $4,000 per square.
• Difficult installation: Installing tile roofing requires professional roofing contractors with extensive experience. The tiles will need to be measured, laid in a specific pattern, and checked so that no moisture gets through. This is not a DIY project.
• Heavyweight: Your roof structure must be able to handle the weight of a tile roof, which may be as much as 850 pounds per square for clay tile and 950 pounds per square for concrete tile. An asphalt roof, by comparison, weighs only around 225 to 325 pounds per square. If you’re replacing shingle roofing with tiles, you should consult an engineer to determine if structural reinforcement is necessary, which will add to the cost of the roof. 
• Tiles are brittle: While very durable, clay tiles, slate, and concrete tiles can be broken if they suffer a heavy impact, such as from falling tree branches, or even due to the pressure of walking on them. Repairs, when needed, can be expensive. 
• Not suitable for all roof slopes: Tile roofs are suitable only for roofs with relatively sharp slopes. They should not be used on roofs with pitches less than 4:12. 

Choosing the right clay tile for your roof

Knowing where your tiles came from can give you a good idea of their quality and suitability for the climate of your region.

One important characteristic of the tiles is the grade. Clay tiles are produced in various grades, and each one provides a different level of resistance to weather-related issues like frosting. The tiles you have should be based on the most severe climatic conditions that can occur in your area rather than the typical climate. 

There are three grades of tile, laid out in the ASTM C1167 Standards for Clay Tile Roofs.  Each grade defines a degree of weather resistance.

What level of moisture absorption a tile may have is one of the main criteria in determining the tile’s grade. The more moisture the tile absorbs, the less likely to perform on harsh climates. One of the worst effects is when water soaks into the tile and then freezes. The tile begins to break down and simply isn’t resistant to freezing temperatures.  Only grade 1 clay roof tiles should be used in extreme freeze thaw climates.

ASTM 1167 also categorizes clay roof tiles by shape:

• Flat Tiles: Small and rectangular with a smooth surface finish
• Roman Tiles: Flat in the middle with a concave curve on one end and a convex curve on the other 
• Interlocking Tiles: Interlocks with adjacent tiles, which improves protection against wind and rain

These shapes effect testing for another important aspect of the tile’s quality: break strength.

Here are the essential steps when renovating a clay tile roof:

• Choosing the right materials: Before even beginning to roof, tiles should be chosen that suit the climate.
• Installing the underlayment: This feature is essential to clay tile roofing in the event of tile breakage or other roof damage and it must be installed correctly to ensure your roof’s water-tightness for such a time.
• Installing the drip-edge flashing and gutters: These items must be of exceptional quality to match the long lifespan of a clay tile roof.
• Laying the Tiles: Clay roofing must be installed appropriately to ensure protection from water as well as to help with its durability. Fasteners should be resistant to corrosion like a 316 stainless screw for installations close to salt water, a 304 stainless screw or nail, or copper nail, for all other areas.

Can your roof support clay tile?

An average, asphalt/composite roofing shingles will weigh roughly 230 pounds per square (this is a 10′ x 10′ area) while most clay tile systems will range anywhere from 600 to 1,100 pounds per square. On the surface, the weight does become an obvious concern.

While tile is heavier, many municipalities allow up to three layers of asphalt/composite roofing shingles. Just for comparison, three layers of asphalt/composite shingles will weigh roughly 690 pounds per square. This means that most roofs, and long as they don’t suffer from maintenance issues, can support lightweight concrete or clay roofing without modification or added support. Still, it is important to seek the advice of a structural engineer for certainty. Nevertheless, even with heavier tiles, most homes will require only minimal reinforcement.