The Durability of Clay Roof Tiles

Fire

• Clay tiles resist fire and do not burn. They can withstand temperatures up to 2,000 degrees Fahrenheit, or about the temperature at which they were fired in the kiln. Glazed tiles may lose their glaze, but they won't melt or burn. This fireproof property made clay tiles very popular during the 18th and early 19th centuries, when house fires were a serious concern. Tiles became less popular as other fireproof roofing came onto the market, but they are still an excellent choice today.

Weather

• Tiles can withstand most weather conditions without suffering cracking or breakage. Even when weather does damage the clay, it usually affects only a few tiles, leaving the roof as a whole unscathed. Replace broken tiles as needed to keep the roof in good condition. Climates with regular freezing and thawing cycles can degrade tiles more quickly than climates where temperatures don't drop below freezing on a routine basis. The rapid expansion of water in the tile as temperatures drop can weaken it and encourage breakage.

Impact

• Clay tiles are relatively hard and strong, but they do break when struck. Hailstones often damage clay roofs, especially when the stones are 1-½ inches in diameter or larger. Impact damage usually cracks or shatters the tile. Most clay roofing tiles are stronger in the center, and weakest along the edges. Hail-damaged tiles often show breakage along the corners or leading edge. Some tiles, such as Spanish, mission and Roman tiles, have a high profile and are easier to break when walking on the roof. To prevent this type of impact damage, place a piece of plywood, sandbags or wooden planks over the tiles and walk on these if you're making repairs to the roof. This distributes the weight over many tiles and reduces the risk of breakage.

Considerations

• Many historic clay tile roofs have been in place for so long that it's hard to match broken tiles with new ones. This is especially true for old roofs made from hand-formed clay, which differs significantly in appearance from newer machine-made tiles. Older techniques, including lead glazing, produced colors that aren't available in modern tiles. When visible tile on one of these roofs breaks, replace it with an existing tile from a less obvious part of the roof. Next, fill in the gap with the closest modern match available to preserve the appearance of the roof.