Cracked tiles on floors and walls are a problem because it can be difficult to track down the source of the crack. In many cases, the crack is not the result of an inferior tile; in far more instances, the crack was caused by anomalies under or around the tile. Hairline cracks in tile may result from remote, obscure reasons such as improperly cured concrete or flexing underlayments and joists. Identifying the source of the tile crack is the first step toward repairing that crack or the tile itself.
01 of 07
Tile Received a Sharp Blow
If the crack is located in one area and it extends across only a single tile, the crack was likely caused by a sharp blow to the tile. Sometimes, you will see a chip taken out of the tile where the object hit.
In kitchens, especially, where heavy objects such as cans, pots, and pans get dropped, ceramic tiles frequently break. Building standards (ASTM C648) do not regulate sharp blows to tile, only heavy dead loads. Doorways are another common spot for impact-related tile cracks because items may be dropped while opening the door. In general, these types of cracks will be found near the periphery of the floor, not the center.
02 of 07
Tile Cracked Under Heavy Loads
Did the refrigerator's dead weight cause the tile to crack? This is possible.
Most tiles comply with ASTM C648 Breaking Strength standards. In this test, floor tiles are run through a machine that exerts loads on an unsupported 1-inch square area. As long as the tile does not break under 250 pounds of pressure, the tile is considered to be compliant with these standards.
Most tiles meet the 250-pound minimum. Some specialty tiles greatly exceed the minimums. For example, Durabody brand tiles from the manufacturer Interceramic have a breaking point of 400 pounds per square inch.
A sizable refrigerator such as a 22 cubic foot side-by-side model weighs about 300 pounds, representing about 75 pounds per square inch of breaking force on each of its four legs. This is far less than ASTM standards.
However, keep in mind that this is dead weight. Should an errant mover let a fridge, table, dishwasher, or cabinet land too hard on the floor, this is considered a sharp blow and could easily crack the tile.
03 of 07
Tile Was Installed Over a Control Joint
Control joints in concrete are essentially preplanned cracks. Since it is almost certain that concrete will crack at some point in the future, control joints allow you to place those cracks in a predictable fashion. Control joints are intended to create a weakened area in the concrete and regulate where cracks will occur, normally as a straight line, rather than chaotically. It is not prudent to use tile to bridge a line that you know in advance will expand.
04 of 07
Tile Was Installed on Improperly Spaced Joists
With tile, the less deflection, the better. Wood is flexible; tile is rigid. So, if you have a floor with flex, you are attempting to mate two dissimilar materials.
Joists are the wood beams that run under the subfloor and that hold up everything above subfloor—mortar, tile, contents of the room, people. Joists that are spaced too far apart will allow for deflection in the plywood subfloor, thus forcing the floor tile to bend, which it does not want to do. Joist spacing must conform to the International Residential Code. Additional underlayment structures help control flex, as well.Continue to 5 of 7 below.
05 of 07
Tile's Concrete Substrate Has Cracked Over Time
It is not unusual for concrete basement floors, driveways, or patios to have a long crack or two running through them, especially if the concrete is several years old.
Even though concrete seems like the perfect substrate for tile, it carries its own, unique set of problems. When the concrete substrate cracks, this movement is transmitted to the tile above in the form of a reflective crack. If the tile cracks are long, continuous, and extending across multiple tiles, the concrete below has likely cracked.
The only wholesale cure is to strip the tile and then install a crack isolation membrane before installing tile again. These membranes are designed to uncouple the tile from the concrete substrate, allowing the tile to move separately from the concrete.
06 of 07
Concrete Substrate Below the Tile Did Not Cure
Newly poured concrete is full of water. As the concrete cures, the water evaporates and the concrete shrinks. This dynamic process helps the particles and aggregate within the concrete bind tightly together. But this process also has the residual effect of stressing tile that has been installed on it before the concrete has fully cured.
The Tile Council of America recommends that you let the new concrete cure for "as long as possible" or at least for 28 days. Some thin-set manufacturers recommend only 14 days of curing time before installing the tile, but the TCA believes that this is not long enough.
If you have a new home with cracked tile, especially hairline cracks, there is a distinct possibility that the concrete did not cure long enough.
07 of 07
Inferior Tile Was Used
Because the tile is cracked, and the tile is the only visible portion of the installation sandwich of mortar and substrate, most homeowners assume that the tile is at fault. Usually, this is not the case; but it is possible that you or a previous owner has installed sub-standard tiles.
Tiles purchased through established retail lines such as home improvement stores and reputable online outlets tend to be in compliance with ANSI and ASTM testing standards, which regulate tile strength. Always check the specifications section of the manufacturers' site or printed literature about the tile.