Can you recommend a tile to use on a cottage floor? We have tried two types, but both times, in the spring, they rose up and became loose. This is a three-season cottage, with an insulated plywood subfloor.
—Margaret and Fred Taylor, via e-mail
The problem likely isn’t the tile itself. Any type should do, assuming you prep the floor and install the tiles correctly. “It’s not rocket science,” says Chris Sturdy, the owner of Durham Tiling Expert, “but it is science.”
That said, the conditions in a three-season cottage (unheated in the winter, we assume) will affect the subfloor—and that can affect the tiles’ adhesion. With freezing and thawing, “you can have some pretty extreme moisture shifts,” explains Pierre Hébert, the technical services manager with Mapei Canada, a company that makes adhesives, sealants, and other products for construction. This causes the plywood to shrink and swell; if the tiles don’t move in the same way, they can come loose. “It’s not a favourable environment. There’s going to be floor movement. You can’t avoid it.”
Other factors could compound the problem, for example, if the subfloor is sitting over dirt, with no vapour barrier in between. “You could have lots of moisture buildup under the tiles, and this leads to pop-up,” says Russell Richman, an associate professor of building science at Toronto’s Ryerson University.
To avoid the temperature shifts, you could leave the heat on low in the cottage all year round. But that’s expensive, inconvenient, and impossible in some cottages. Instead, try an installation-related solution, such as putting a buffer in between the plywood and the tile. One option is a layer of cementitious backer boards. They’ll help absorb some of the movement from the plywood so it isn’t transferred to the tile; look for them in home renovation stores. “Assuming the cottage floor isn’t hundreds of square feet, it’s an inexpensive fix,” says Hébert.
It’s also worth using a high-quality mortar, say our experts, such as a two-component system that includes powder and latex portions. It’ll cost more…but it may save some future aggravation.