FAIMEWhy Are My Tiles Cracking or Coming Loose? Tap Them First
Cracked tiles, cracked grout and tiles that sound hollow underfoot are almost never a problem with the tile itself. They are what you see when the layers under the tile moved, or never bonded properly. The pattern of the damage tells you which.
Tiles crack or come loose because of what is underneath them. Tap the floor with a coin or the handle of a screwdriver: a hollow sound means the tile has lost its bond to the mortar, usually because there was not enough mortar coverage when it was installed. A crack that runs in a line across several tiles follows a crack or joint in the floor below. Cracks scattered across a wood-framed floor point to a floor that flexes too much. Grout cracking along walls, corners and the tub edge usually means those joints were grouted when they should have been left flexible and caulked. Regrouting fixes none of these unless the tiles are solid.
The tap test
Drag a coin, a set of keys or the handle of a screwdriver across the floor and listen. A solid tile gives a sharp, dull click. A hollow, drummy sound means there is a void under the tile, or the tile has let go of its mortar. Mark the hollow tiles with tape. If they are scattered, the problem is installation. If they cluster in one area, something underneath moved or got wet.
Read the pattern of the damage
What the pattern points to
- A crack running in a line across several tiles: a crack, joint or seam in the concrete or subfloor below, telegraphing up
- Scattered cracks on a wood-framed floor: the floor flexes too much under load for tile
- One cracked tile with a hollow sound: a void under that tile, then a heavy point load such as a dropped pot or a fridge leg
- Tiles lifting or "tenting" in the middle of a room: no room left for movement at the walls, so the field had nowhere to expand
What was likely missed at install
- Full mortar coverage under each tile, with large tiles back-buttered
- A crack-isolation membrane over a cracked slab
- A stiff enough floor for the tile chosen. Natural stone needs a stiffer floor than porcelain or ceramic
- Movement joints at walls and in large tiled areas, left flexible and caulked rather than grouted
Why grout cracks
- The tiles are moving. If grout cracks around tiles that also sound hollow, the grout is just the first thing to show it. New grout will crack again.
- Corners and changes of plane were grouted. Where a wall meets the floor, where two walls meet, and where tile meets a tub, the joint should be a flexible sealant. Grout there cracks as the building moves with the seasons.
- The grout was mixed too wet or not packed fully into the joints, which leaves it weak and shrunken.
Cracked tile in a shower is a water problem
On a floor, a cracked tile is mostly cosmetic for a while. In a shower or tub surround it is a leak. Water gets through cracked grout and failed caulking every time the shower runs, and if there is no waterproof membrane behind the tile, it soaks into the wall board behind it. Signs it has gone further than the tile:
- Tiles that flex or move when pressed
- Grout that stays dark long after the shower is dry
- A musty smell, or peeling paint on the wall outside the shower
- A stain on the ceiling below the bathroom. See what a ceiling water stain means.
How it is fixed properly
Find the cause
Tap-test the whole area, look at the crack pattern, and check the subfloor or slab. In a shower, check whether the board behind the tile is wet or soft.
Local problem: replace the tiles
A few cracked or hollow tiles with a local cause can be cut out, the old mortar ground off, and new tiles set with full coverage and regrouted. Keep spare tiles from the original job for exactly this.
Widespread problem: fix what is underneath
Many hollow tiles, or cracks running in lines, mean the substrate has to be dealt with: stiffening the floor, a crack-isolation or uncoupling membrane, or in a shower, new board and a waterproof membrane.
Movement joints and sealant
Perimeter gaps, corners and the tub edge are finished with a flexible sealant, not grout, so the next seasonal movement does not crack them.
Where FAIME fits
Tile and flooring work is self-performed by FAIME's own setters: floor and wall tile, shower surrounds, backsplashes and repairs, in houses, condos, stores and commercial units across Toronto, North York, Scarborough, Etobicoke, Vaughan, Richmond Hill, Markham, Mississauga, Brampton and the wider GTA. We start every tile job with the substrate, because that is where tile failures start. More on how we approach it in our tile and flooring guide.
- $2M general liability · Active WSIB (Class G5) · 2-year workmanship warranty
- Written scope after a free site visit. No pricing before we have seen the floor.
Frequently Asked Questions
Why do my tiles sound hollow?
A hollow or drummy sound means there is a void under the tile or it has lost its bond to the mortar. The most common cause is incomplete mortar coverage when the tile was installed. A few scattered hollow tiles may never crack; a cluster of them, or hollow tiles that move, will.
Why are my floor tiles cracking in a straight line?
A crack that runs across several tiles in a line almost always follows a crack, joint or seam in the concrete slab or subfloor underneath. Replacing the tiles alone will not stop it; the crack below needs a crack-isolation membrane or other substrate fix first.
Can I just regrout cracked grout?
Only if the tiles themselves are solid. If the grout is cracking because the tiles are moving or hollow, new grout cracks again. Grout cracking only at corners, along walls or at the tub edge usually means those joints should be caulked with a flexible sealant instead.
Is cracked grout in the shower a problem?
Yes. Every shower pushes water through cracked grout and failed caulking. Without a waterproof membrane behind the tile, it soaks the wall board and framing, which is how showers end up needing to be rebuilt. Fix it early.
Can a single cracked tile be replaced?
Usually, if the cause is local, such as a dropped object over a small void. The tile is cut out, the old mortar ground off, and a new tile set and grouted. Matching is easiest if spare tiles were kept from the original installation.
Does FAIME repair and install tile in the GTA?
Yes. Tile and flooring is self-performed by FAIME's own setters across Toronto, Vaughan, Richmond Hill, Markham, Mississauga, Brampton and the wider GTA: floors, walls, showers, backsplashes and repairs. FAIME is WSIB Active under Class G5, carries $2M general liability and backs its workmanship with a 2-year warranty. Site visits are free.
Want this looked at properly?
We come out, look at the actual condition, and put the scope in writing. No pricing is given before a site visit — and we will tell you if the work does not need doing.
$2M general liability · Active WSIB (Class G5) · 2-year workmanship warranty