Terracotta Tiles
Production and Properties
An appropriate refined clay is shaped into the desired shape. After drying it is placed in a kiln, or on top a combustible material in a pit, and then fired. The typical firing temperature is around 1000°C. The iron content gives the fired body a yellow, orange, red, "terracotta" colour. Terracotta, if un-cracked, will ring if lightly struck.
Terracotta was the only ceramic produced by Western and pre-Columbian people until the 14th century, when European higher fired stoneware began production. Terracotta has been used throughout history for sculpture and pottery, as well as bricks and roof shingles. In ancient times, the first clay sculptures were dried (baked) in the sun after being formed. Later, they were placed in the ashes of open hearths to harden, and finally kilns were used, similar to those used for pottery today. However only after firing to high temperature would it be classed as a ceramic material.
Because terracotta is both elegant and versatile, it has never gone out of fashion. Terracotta floors have been with us for centuries and can still be laid in various styles, each characterised by quality, durability and easy maintenance.
Advice and Suggestions
Laying
Terracotta tiles must be laid with gaps 8 to 10 mm wide, whether using mortar (soak the tiles in water beforehand, for at least half a day) or adhesive.
"For exterior floors, in the event that these are exposed to the elements and installed in areas with particularly hostile climatic conditions, the distance between expansion joints must not be more than 2-3 m. If the exterior floor is restrained between walls or kerbs, frequently the case in practice, a perimeter expansion joint must be included (as for an interior floor restrained between walls)."
"One of the main requirements for exterior floors is that rain and other water should be able to run off easily, avoiding stagnation that could result in infiltration and subsequent danger to the structure and, in the event of frost, to the tiled surface itself, if not classifiable as frost proof on the basis of the usual standard tests. For this reason, floors must have an adequate gradient". Accordingly, a gradient of 1.5-2% approximately should be ensured.
Grouting and Sealing
Joints should be grouted using a sand and cement mix if larger than 15mm. For standard grout joints, it is recommended that a formulated grout product is used. Grout joints a little at a time in order to prevent the grout hardening on the surface of the terracotta; ensure the grout penetrates well into the joints, then smooth the floor with a trowel and brush well with a damp sponge to clean the surface of the terracotta. Dependant on the porosity of the terracotta, a suitable sealer is recommended. Traditional Italian terracotta must be sealed with a Tile Doctor HP sealer (remember, sealing a terracotta tile will darken the surface). Sealing of a terracotta tile is not a once off procedure. It is recommended that the tiles are sealed at least once a year. Terracotta tiles become more beautiful with age and wear. This is the beauty of this traditional floor covering.