What Causes Porcelain Tile to Crack?

Subfloor Deflection

• Porcelain tile requires a solid, stable foundation. All tile, regardless of its composition, will crack if bent too far. This bending is referred to as deflection. If you install porcelain tile on top of a subfloor that allows excess deflection, the tile or the grout holding the tile in place, is likely to crack.

Firing Cracks

• Porcelain tile is created under conditions of extreme heat during a process known as firing. If the glaze is not applied evenly during the manufacturing process, the glaze may crack during firing. This is known as a firing crack. Although the porcelain tile itself is not cracked, the crack in the glaze makes this tile unsuitable for use as a whole tile. The portion of the tile that does not have cracked glaze may be cut with a wet saw and used as a cut tile.

Impact

• Porcelain tiles are extremely tough and can stand up to repeated foot traffic. However, they can crack if subjected to an impact from a heavy object. Impact cracks are most likely to occur in conjunction with improper bonding of an individual tile, according to the Environmental Home Store website.

Cracked Slab

• Porcelain tiles that are laid on top of a concrete slab may be subject to the same forces that can affect the slab. Porcelain tiles and concrete have different rates of contraction and expansion when exposed to cold and heat, which can produce stress on the tiles. A crack in the concrete slab can result in a crack that extends from one porcelain tile to another in a continuous line.