Deal With Cracked Tiles

For the most part this reputation is entirely deserved. We use tiles in all manner of locations where other materials just wouldn’t be up to the job. With such a hugely diverse range of applications, they are exposed to conditions ranging from the very hot and humid to temperatures of freezing and below, not to mention daily knocks from furniture, people and other objects.

We think little of our tiles and how they are used, that is until the day we spot some damage. We are then faced with the unenviable job of dealing with a broken tile, and unless you happen to have done this before, it can be difficult to know where to start.

What causes cracking?
Cracking can range from minor imperfections affecting an individual tile, through to large, continuous cracks appearing in a run of tiles.Movement in the substrate material will cause a linear crack that may run through several tiles, whereas individual fractures are usually caused by either a knock or a faulty tile.

If the tiles have been laid over concrete then a linear crack will suggest the underlying slab is moving also. If the cracking is apparent along a joint between two different slabs, then an expansion joint should have been installed in the tile course, as this suggests that this area was the junction of two slabs.

Similarly, if the cracking happens where an underlying concrete slab meets a different substrate material, then an expansion joint should have again been installed. These allow for differing rates of expansion and contraction and avoid problems with cracked tiles.
Multiple cracks in a straight line when over a concrete substrate?

This is generally due to hurriedly tiling over immature concrete. Freshly poured concrete should be left for at least 1 month for every 25mm depth of concrete in the slab. A 100mm slab, for example, should be left for at least 4 months before having a tiled finish applied. Shrinkage cracks in the slab will otherwise continue through to the tiled surface.

Stressing of the foundation rods can also be apparent during the curing of the concrete slab. Again, unless adequate time is left for the complete curing process then any cracking in the slab will be transferred through the tiles.

What to do if you see cracking
Try to understand what has caused it. If you are lucky then it may just be a single damaged ceramic tile that can be fairly simply cut out and replaced.

If the cracking has happened in a straight line of porcelain tiles, give some thought to whether an expansion joint ought to have been installed. At their most simple these are just a break in the tilling course to prevent movement causing damage. They are usually installed as two L-shaped opposing aluminum-angle lengths, separated by a length of rubber.