Why do tiles crack?

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Over the years, I’ve received many emails from homeowners asking me why their tiles have cracked. Unfortunately, this is still a common question. So, let's review why this can happen.

Tiling is not a DIY project unless you are a very experienced handyperson. I always recommend hiring a professional tile setter. Why? Because good tile setters have spent years honing their craft. They have the necessary materials, equipment, supplies, skills and experience to be efficient.

Typically, improper installation is what causes tiles and grout lines to crack. However, this can also happen when the substrate — the surface on which the tiles are laid — experiences drastic temperature changes, is overloaded, or a heavy object is dropped on the tiles.

The quality of the tile can also be a factor. Thin cheap tiles are often not strong enough to absorb the impact of a heavy object, resulting in cracks or chipped tile. Most tiles have a thickness of between 6 and 10 mm. However, better-made tiles are at least 10 mm thick and exceed the breaking strength standard of 250-pound minimum.

You’ll have to contact the manufacturer to confirm the breaking strength standard, as it's typically not mentioned on the packaging. Also if you’re planning on doing in-floor heating, consider ceramic, porcelain or natural stone tiles as they are great heat conductors.

Before you lay any tile onto the subfloor, be sure it is solid and reasonably even. It should also be free of any debris. Another important factor is checking that you don't have any structural issues and that the joists are properly spaced.

So what should you do if you have any of these issues?

A floor levelling mixture may do the trick if your floor is uneven. A self-levelling mixture helps provide a level surface and can eliminate any dips and imperfections in the floor, but it can also help prevent tile and grout from cracking and squeaking.

If you have structural issues or if your joists are not properly spaced or supported, your floors may sag or be uneven which can lead to cracked tiles. You should speak with a structural engineer and hire a contractor to replace the problematic beam or sister the joist. Sistering a joist refers to reinforcing an existing beam and can minimize the bouncing when you walk over a floor. You can use framing lumber or 3/4-inch plywood strips for the sister joist.

I am often asked, "Is it OK to tile or put flooring over an existing floor?" To me, that is a resounding NO! Never install a new floor on top of an old one. Why? Because you want the flooring transitions between each space to be seamless and to not be a tripping hazard.

Also, you may run into issues securing the old floor with the new floor, as not all adhesives adhere to all surfaces. Glazed or polished surfaces, as an example, can be a challenge.

You also increase the floor's surface weight and height, which applies to both wall and floor tiles. Last but not least, there is a chance that tiles can lift as a result of air pockets or water becomes trapped between the layers, which will harm your tiles and grout as well as cause rot and mould.

Tile underlayment is essential to even out rough patches in the subfloor and to add a rigid layer that stops the floor from flexing when people walk on it. Without one, even the slightest subfloor movement can cause tiles to break and grout lines to fall apart. I often use an uncoupling membrane and a floor-warming system in one. The added benefit of the uncoupling membrane makes for easy in-floor heating application and helps minimize floor movement, preventing tiles and grout from cracking.

I also like using a thin set when laying tile. It's a modified mortar designed for tiles and is thinner than other mortars. It provides properties that allow for small movements between rigid tiles and the substrate without compromising the stability of the tile. Correct mortar application is also essential, so ensure the mortar covers the back of each tile entirely and avoid any voids or gaps, as this will compromise the surface strength, creating weak spots and, eventually, cracks.

Tile flooring is a practical choice and, when installed correctly, will last for many years. To prevent tiles and grout lines from cracking, always follow manufacturer's requirements, do your research, use the right products and hire a professional tile setter for the best results.

Residents of the GTA can apply for season 2 of Holmes Family Rescue at www.makeitright.ca

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