Why Tile Is Cracked and How to Avoid It

Tile Received a Sharp Blow

If the crack is located in one area and 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 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.

How to Avoid This

Gel mats help you stand for longer periods of time in the kitchen with fewer leg and back aches. They also absorb the shock from heavy, dropped items that may crack tile.

Tile Cracked Under Heavy Loads

Did the refrigerator's dead weight cause the tile to crack? While not common, 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 a mover or delivery person 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.

How to Avoid This

Make sure that the bottom of the tile and the subfloor receive the correct amount of thinset. Hollow pockets of air between the tile and subfloor may cause cracking, even when the dead weight is within parameters.

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.

How to Avoid This

It is not prudent to use tile to bridge a seam that you know in advance will widen. It is practically a given that the tile will crack.

If the tile has not yet been installed, avoid control joists or use an isolation membrane.

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. That's why floor coverings that flex—vinyl, laminate, carpeting, and even solid hardwood and engineered wood—work so well on raised, joist-based floors.

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.

How to Avoid This

Joist spacing must conform to the International Residential Code. Additional underlayment structures help control flex, as well.

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 extend across multiple tiles, the concrete below has likely cracked.

How to Avoid This

The wholesale cure is to strip the tile and then install a crack isolation membrane before installing the tile again. These membranes are designed to uncouple the tile from the concrete substrate, allowing the tile to move separately from the concrete.

If the tile has not yet been installed, speak to the tile company or contractor about using a crack isolation membrane. This product is now considered standard for most tile-to-concrete installations.

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.

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.

How to Avoid This

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 tile thinset manufacturers recommend only 14 days of curing time before installing the tile, but the TCA believes that this is not long enough.

Given the distinct possibility of tile cracking due to improper concrete curing, let the concrete cure for at least a month before tiling.

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.

How to Avoid This

Expensive doesn't necessarily equate with higher quality, so do your research. 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.