The most commonly used roofing tile are manufactured products consisting of molded, hard-burned shale or mixtures of shale and clay, but metal tile are also available. When well-made, clay tile are hard, fairly dense and durable, and they may be obtained in a variety of shapes and textures. Most roofing tile of clay are unglazed, although glazed tile are sometimes used.
Clay tile roofings of good quality that have been properly laid require very little maintenance. If a tile is broken, it should be removed with a nail ripper and replaced with a new tile set in roofing cement of the same color as the original tile. Flashings should be inspected periodically, and gutters and leader heads should be kept clean.
Clay tile may be applied over an old roof covering provided the covering is in reasonably good condition. The roof framing should be examined to determine whether or not the additional weight of the tile can be carried safely and, if not, additional framing or bracing should be added.
Where the old roofing is left in place, all defective portions should be repaired and the surface made as smooth and solid as possible. If the old roof covering is too worn or damaged to provide a proper laying surface for the new tile, it should be removed and the sheathing or roof decking made smooth and solid to receive the new tile.