Short answer: often, yes. Tiling over tiles is an accepted method when the existing floor is sound. It saves the demolition, the skip and the dust of taking the old floor up. But it is not free of consequences. The reasons a good tiler hesitates are the same reasons a lot of people end up asking us about the alternative. Here is the honest picture on both.
When tiling over tiles works
The existing tiles have to be firmly bonded, flat and clean. A tiler will tap the floor for hollow tiles, check it for lippage and level, degrease it and either key the glazed surface or use a primer made for tiling over tiles, then a flexible adhesive rated for the job. Done that way, over a floor that was solid to begin with, the new floor is as stable as the old one.
Where it goes wrong
Height. A new tile and its adhesive bed add ten to fifteen millimetres. Doors need cutting, thresholds change, the step into the next room appears from nowhere and a level-access shower stops being level. In a bathroom the toilet and bath connections may need adjusting too.
Hollow tiles. Any tile that rings hollow has already lost its bond and will not hold whatever goes on top of it. A few can be lifted and re-bedded. If there are many, the old floor is coming up whether anyone wants it to or not.
Weight. On a timber floor the extra load of a second tile bed matters. On a solid floor it does not, but the deflection of a suspended timber floor is what cracked the first tiles. A second layer does nothing to change that.
The grout lines underneath. They are a pattern of weak points. A flexible adhesive copes with them; a rigid one telegraphs them through as cracks in the new grout a year later.
Moisture. A tiled floor is not vapour-open. If there has ever been a leak under it, the substrate can hold that water for years and a second layer seals it in further.
The alternative that avoids most of this
A large share of the people who ask whether they can tile over tiles do not want tiles again. They want the old floor gone and a clean, continuous surface in its place, without the demolition. That is what microcement over existing tiles is for. It is applied at about three millimetres, so the height problem disappears: doors stay as they are, thresholds do not move and a level shower stays level. There are no joints, so nothing telegraphs through and there is no grout to scrub. And because it is bonded to the tiles in the same way a new tile bed would be, the checks are the same ones a tiler would make, which is why we do them before we quote rather than on the day.
We have written the full method out here: the tap test, the height check, the moisture check and what happens when a floor fails them. It is worth reading before you decide either way, because the same three checks decide whether tiling over tiles is safe too.
When we would tell you to tile instead
Microcement is a hand-applied mineral finish and it suits people who like a continuous, slightly variable surface. If you want a strong pattern, a very hard-wearing commercial floor with heavy point loads, or the option of replacing a single damaged unit, tile is the right answer and we will say so. We are not a tiling company and we would rather point you to one than talk you into the wrong floor.
What to check before you decide anything
- Tap the floor. A dull note is a bonded tile. A hollow, drummy note is not. Count the hollow ones.
- Measure the height at every door, threshold and shower former. Write down what ten to fifteen millimetres would do to each. Then write down what three would.
- Think about water. Any leak in the history of that floor, however long ago, is worth mentioning to whoever quotes.
- Decide what you actually want to see. If the answer is "not tiles", the question changes.
Our floor build-up is here and the bathroom page shows what a grout-free wet room looks like. If you would like us to look at a tiled floor, send a photograph and a postcode and our design team will be in touch.