Why Tiles Crack
Tile cracks for only one main reason, something in the installation process was done wrong. Now, this could be many many things. In this article I explain 4 main reasons tile cracka and how to make sure you can avoid them at all cost.
Hollow Tile
Hollow tile is by far the most common reason for them to crack. This is because as strong as tile is, if it is not supported properly from underneath with thinset there is a risk of the tile breaking if something is dropped onto them. This is commonly seen when tile are installed with the “dot” method. The dot method does allow the installer to get perfectly flat floors and walls, but the drawback is that there is little adhesion or support behind the tile. Another way for tile to be hollow is because of an installer using to small of a notch trowel. An example of this I have seen personally is someone using a 3/16” notch trowel when installing 12x24” tile. This is a big no-no because there is no possible way to ensure there is enough thinset to support the tile.
To make sure this doesn’t happen with your home or install, make sure you are using the proper sized notch trowel and you are collapsing the ridges.
2. Unbonded or loose tile
Unbonded and loose tile are something that is pretty common to see in some installations. This can be caused by a couple things, but the most common is not back- buttering tile before installing, and not wiping the back of tile with a wet rag or sponge before installation to make sure there is no kiln release left on the tile. With back buttering I personally do it on all tile unless it is on a mosaic sheet. But when getting into tile that is larger 12x12” and up, back buttering is a necessity no matter what. If back buttering is skipped there is a chance the tile does not have the opportunity to bond correctly with the thinset and it eventually gives loose. Another reason tile could become loose is that kiln release was still present on the backs of the tile during the installation process. This is something that many installers and homeowners alike do not think about, but it is something that could destroy a project. I have seen people pulling up full tile in a demo with nothing but their hands and then showing that the tile technically had full coverage underneath it. The installation would have been bulletproof and lasted years, but instead one single step was not completed and it ruined the project.
The best way to make sure this doesn’t happen to you is to wipe off tile before installation and to make sure you back butter.
3. No Perimeter or Expansion joints
Expansion joints in floors and walls are extremely important when setting tile. Something that not many people know is that tile actually expands and contracts. It’s said that a 12x12” tile can move the thickness of a sheet of paper. Although this is not a lot, when compounded over the distance of an entire floor it could grow to be a large amount. Making sure there is perimeter gap against existing framing, baseboards, door trim, or existing cabinets is a necessity. When this small step is overlooked tile can actually expand to the point that it actually explodes from the floor because of the pressure. This can also happen if there is a large tiled area that does not have any soft joints throughout it. These soft joints allow the tile to move enough that they won't break or become unbonded or break.
Making sure there is a perimeter joint around the room or wall you’re tiling is the best way to avoid “tenting” or unbonding. The only time you should worry about expansion joints within the floor is when there is a very large space or one that is in direct sunlight, an expansion joint is typically filled with a color match silicone matched to the grout color.
4. Faulty substrate
Faulty Substrate can cause catastrophic failures in tile installs. If installing tile on a floor with improper joist spacing it can fail due to deflection. Deflection is when the floor “bends” under certain weight loads which can cause tile breaks, cracks, and unbonding of the tile. Another thing that can cause deflection is not having a thick enough subfloor. Before starting on a project make sure the substrate is thick enough, screwed down properly, and does not have any deflection.
Concrete can also be faulty. If the is a crack through the slab and then tile is directly bonded to it it can can cause the tile to break if it moves again. This can be mitigated though with proper precautions.
The only way to make sure you’re installing over a suitable substrate is to check before installing. Check the joist spacing, subfloor thickness, and deflection levels for wood floor. For concrete floors make sure there has been enough time for the concrete to cure, and also make sure there is no cracks in the concrete.
