By Andrew Hunt
An ounce of prevention is worth a pound of cure, especially when installing tile, which can be unforgiving. The bane of both homeowner and tradesman is the crack across the countertop or, worse, a split in the tub surround. But installed correctly, tiles can provide decades of beautiful service to a home.
Here are a few of the usual suspects that can lead to cracks in your tile, and information on how avoid these issues:
Problem: Fevers and chills.
Tiles are very sensitive to the changing of the season because of rapid changes in temperature and humidity. When the home gets cold in the winter, tiles get even more brittle, and the adhesive underneath can begin to contract. When the heat kicks, on rooms can go from cold to hot in a matter of minutes. Because tiles are denser than the surrounding grout and subfloor, they will expand and contract at a different rates.
Solution: Flexible thinset and isolation membranes.
The key to keeping tiles intact in areas where there will be rapid changes in temperature is to allow the tiles to "float" above other materials that will expand or contract at different speeds. In the case of tiles applied over concrete floors, an isolation membrane can be put down to cover any current or future cracks that might run through the subfloor. A thinset with a latex compound added can also decrease the chance of cracks later on, but care should be taken in areas prone to water.
Problem: Water down below.
Because tiles are so common in areas prone to water, such as bathroom floors, countertops and tub surrounds (not to mention swimming pools), having a plan for managing moisture is critical. Once water finds a way to get past the sealer applied to the top, it can infiltrate the backerboard and subfloor, causing quick saturation and punky expansion. Tiles crack, and framing members can become damaged over time. It's critical to focus on water management in key areas such as shower pans and joints between materials like backerboard and shower pan.
Solution: Water barriers.
"Green board" or water resistant drywall in tub surrounds just won't cut it anymore. New backerboards offer a treated gypsum core and fiberglass face to help keep moisture from saturating studs. Single-piece shower pans and liners, when properly installed, also are great for keeping water from reaching the subfloor. Repeat, when properly installed. In areas that are often wet, the best bet is to expect water to seep behind your tiles and proactively find a way to direct it down and away, not further into the home.
Problem: A statue of clay feet.
Quick and careless installation of tiles on surfaces that aren't designed for tile adhesives will always lead to trouble. Certain materials don't bond well to each other. Also, when installing a floor of tiles, you will need to know how stable and stiff your subfloor is. For instance, oriented strand board (OSB) is a fine subfloor, but it is relatively weaker than plywood. The more flex or bend (deflection is the technical term) in your floor, the greater the chance of cracking later on.
Solution: Backerboard and strong subfloors.
You just can't say enough about the benefits of using quality backerboard when installing tiles. Whether you go with some of the newer, high-tech versions or plain old cement board, your tiles will thank you for years. Backerboard also will help reduce deflection if properly installed over a subfloor, and it can act as an insulating barrier for rapid temperature changes. But even with a nice slab of cement board to work on, you still need to make sure that your floor joists are no wider than 16 inches apart. A better bet would be to install 5/8-inch exterior plywood as a subfloor first, then add backerboard. This combination will provide a solid foundation for your tiles in most standard-sized rooms.
Keeping tiles from cracking really comes down to a little extra effort up front before you mix the thinset. By providing a solid, water-resistant, stable platform for your tiles, you can ensure decades of crack-free beauty.
Andrew Hunt is a freelance writer who specializes in building technology and green building. He formerly worked for BuildIQ.
| 
