It is a truth universally acknowledged, that a householder in possession of a tired bathroom must be in want of a shortcut. And tiling over existing tiles does look, at first sight, remarkably like one. No hammering, no skip on the drive, no plaster dust settling in the biscuit tin.

So, can you do it? Yes, provided the old tiles are firmly bonded, reasonably flat and completely dry, and provided you can live with the extra thickness. Before tiling over existing tiles, check the condition of the surface, the finished floor height and the weight the wall or floor will need to carry. Where any one of those fails, the shortcut turns into the long way round, and a rather expensive one. This article is about working out honestly which situation you are in, before a single bag of adhesive is opened. If your verdict is that the old tiles must go, our guide to removing them is the natural next step.

You may, madam. But only if the tiles are, in fact, perfectly sound. That word is doing a great deal of work, so let us examine it.

The Case for Tiling Over Existing Tiles

Stripping tiles is the noisiest, dustiest and least predictable part of any refit. The old adhesive is sometimes stubborn, and sometimes the tile comes away with a fist of plaster attached, and then one is replastering a whole wall to tile a splashback. Leaving the old surface in place saves the labour, the waste disposal and the several days of disruption, and in a house with one bathroom that is no small thing.

It can also be kinder to the room. A stable, well-fixed old tile is a decent substrate, often better than a freshly patched wall. That is the argument for tiling over, and it is a fair one. The trouble is that it only holds when the old tiles really are what they appear to be.

Four Tests Before You Commit to Tile on Tile

None of these needs special equipment. A free afternoon and a critical eye will do, and it is worth being a little unkind to your old tiles while you are at it.

1. The tap test.Knock along every row with a knuckle or the handle of a screwdriver. A sound tile gives a dull, solid note. A hollow, drummy one has lost its grip on the wall. One or two loose tiles can be lifted and refilled, but if the hollow sound turns up across the surface, the bond is failing and new tile on top will fail with it.
2. The straightedge.Lay a long level or straight length of timber across the surface at several angles. Gaps of more than a few millimetres over two metres are a warning. Tiling over old tiles does not correct a wall that is out of true, it copies the fault and often exaggerates it.
3. The damp check.Look for black mould behind silicone, stained or blown grout, soft plaster at the edges, or a chalky white bloom on the surface. If water is getting behind the tiles, covering them merely hides the problem while it worsens. Find the source first.
4. The edge inspection.Check corners, window reveals, around the bath and beside the door. Cracked or missing tiles in these places often tell you what the middle of the wall is too polite to admit.

Walls and Floors Do Not Behave Alike

People tend to ask about tiling over tiles as if the answer were the same everywhere. It rarely is. A wall worries about weight and a floor worries about height, and each has its own list of awkward corners.

Swipe to read the whole table

Height and Weight When Tiling Over Existing Tiles

A new tile, the layer of adhesive beneath it and the old tile below all add up. In practice you are usually looking at something like a centimetre or a little more of extra build-up, and on a floor that has consequences. Doors may need trimming, a toilet may need its outlet raised, radiator pipes may end up looking rather short, and a threshold to the landing can turn into a step where there was none.

On walls the extra thickness matters less than the extra weight. Ceramic and porcelain are heavy, and two layers of them on an older lath-and-plaster wall or a thin partition need thought. If you have any doubt about what is behind the tiles, that is a reason to open up a small area and look, not to hope.

Preparing for Tiling Over Existing Tiles: The Sequence That Matters

If the tests are passed and the height is acceptable, the preparation is what separates a job that lasts ten years from one that lasts ten months. Glazed ceramic is smooth and barely absorbent, and adhesive has very little to grip. Every step below exists to give it something.

1. Clean properly.Remove soap scum, grease and limescale with a strong degreaser, then rinse and let the surface dry fully. Adhesive will bond to a clean tile and to nothing else.
2. Key the glaze.Abrading the surface with a suitable tool gives the adhesive a mechanical grip. Follow the adhesive manufacturer’s instructions on how far to go.
3. Prime the surface.A bonding primer made for non-porous backgrounds is usually recommended before tiling over glazed tile. Check the data sheet of your chosen adhesive, since requirements differ between products.
4. Deal with the grout lines.Recessed or damaged joints should be filled and levelled so the new tile is not sitting on a network of small voids.
5. Choose the adhesive with care.This is the step people rush, and it is the one that matters most.

Why a Flexible S1 Adhesive Suits Tile on Tile?

Two layers of tile with two layers of adhesive between them will move a little as temperatures change and as the building settles. A flexible, deformable adhesive gives that movement somewhere to go, where a rigid one would let it show up as cracked grout or a tile that sounds hollow within a couple of years. S1 adhesives are designed for exactly this sort of work, and they are a common choice on larger tiles, on floors and on any substrate that is not a plain fresh screed.

Palace Gel-Tec S1 is a flexible white wall and floor adhesive supplied in 20kg bags, and it is the product we recommend readers consider for this kind of overlay job. White has a practical advantage under pale or slightly translucent tiles, because it does not shadow through. Do read the technical data sheet before you begin, and confirm the primer and surface requirements for your particular old tiles. That advice applies to any adhesive, ours included.

Gel-Tec S1 Flexible White Tile Adhesive, 20kg

A flexible white adhesive for wall and floor tiling, sold by the pallet for renovation projects and trade jobs. Choose the pallet size that suits the work.

Pallet of 15 bags
Pallet of 30 bags
Pallet of 45 bags

When Tiling Over Old Tiles Is Not the Right Choice

There is no shame in deciding that the old tiles must go. If the tap test found hollow tiles in several places, if there is damp behind the surface, or if the height simply will not work, removal is the right answer, and it usually costs less than redoing a failed overlay. Any wet area whose original waterproofing you cannot vouch for deserves the same caution. Our guide to removing old tiles covers how to do it without wrecking the wall behind.

The honest summary is that tiling over existing tiles is a legitimate technique with a narrow window of suitability. Inside that window it saves time and mess. Outside it, it stores up a bigger repair for later.

Buying Adhesive for Overlay Jobs

Overlay work is often a series of similar rooms: a row of bathrooms in a rental portfolio, a run of en-suites, a hotel corridor. For those, buying flexible adhesive by the pallet is generally more economical than collecting bags one at a time, and it avoids the mid-job discovery that the last bag has gone and the merchant is shut. You can compare pallet sizes on our Gel Adhesive Pallet Deals page, and the free UK tile calculator will help you work out the tile quantity for the room before you order.

Frequently Asked Questions