Firstly, to avoid the scenario you see on the left. Tiles which are not fully supported by the adhesive are prone to: a/ breaking under load (when stepped on), b/ breaking due to forces on expansion and contraction. The sub-flooring is in constant motion due to temperature or/and moisture content changes. The wooden part of sub-flooring contracts and expands after every shower session, as wood absorbs moisture and then dries. The “masonry part” (tiles and/or concrete slab under them) contract and expand with temperature changes. Those forces are huge and given enough time they can do amazing things, as shown in the photo.

Check for loose tiles

Every property owner who invested money in tiling should check the tile adhesion on a yearly basis. It’s trivial. All you need is a broom stick and ears. Just sweep the surface with the broom stick and try to catch the sound changes. Tapping tiles with your knuckles works in small areas, but not deck-size things (too hard on knees, spine and knuckles…).

As you “drive” the stick you will catch EVERY drummy tile on your route. Once detected, mark them. Than, grab a phone and call The Extractor. The cost of epoxy injection is nothing in comparison to ending up with broken tiles that are no longer available on the market! You cannot replace tiles if you can’t buy them.

Another indication of tiles becoming loose are “spider web” cracks in the grout. It’s a sign we need to address the forces of expansion and contraction. If left aside, this might lead to delamination of tile adhesive layer. The tiles don’t necessarily have to sound hollow. It is hard to catch by monitoring sound, but it’s visible after close examination of the grout surface.

There is no substitute for epoxy injection if you want to save a waterproofing membrane (showers, decks) or underfloor heating. Only the most clueless of all “grout restoration professionals” replace tiles inside showers or on decks . One has to treat the waterproofing membrane as a holy cow/ Humpty Dumpty. Once breached, it will NEVER be whole again. It is quite terrifying that even some tilers allow themselves not to be fully aware of this fact.