Can I tile over existing tiles?
When overtiling is a legitimate shortcut and when it is storing up a failure — weight, thickness, the state of what is underneath, and what it does to doors and levels.
- Difficulty
- intermediate
- Time
- 30 min
- Read
- 5 min
- Safety
- caution
Short answer
Yes, if the existing tiles are genuinely well bonded, the wall or floor can take the extra weight, and the added thickness does not cause problems at doors, worktops and sanitaryware. Tap every tile first — any hollow or loose ones must come off, and if more than a few are loose the whole lot should go.
Overtiling is not automatically bad practice. It avoids the destruction, dust and plaster damage that removing tiles causes, and it is routinely done well. But the new tiling is only as good as the bond of the old, and it adds weight and thickness that some walls and some rooms cannot absorb.
Safety
Step by step
- Tap the whole area with a knuckle or a coin.A dead, solid sound is bonded. A hollow ring is a void. Map every hollow one. If a handful are loose, take those off and make good; if a lot are, the substrate has already failed and overtiling puts new tiles onto a failing surface.
- Work out the weight.Tile plus adhesive has a real weight per square metre and the substrate has a limit — plasterboard on studs especially. Doubling up on a plasterboard wall can exceed it. The board manufacturer states the limit; heavy stone or thick porcelain over existing tiles on plasterboard is often outside it.
- Check what the extra thickness will hit.On a floor: door clearance, the threshold to the next room, the height of the toilet outlet, appliance heights under a worktop, and any step. On a wall: window reveals, sockets and switches whose boxes will now be too deep, and shower valves.
- Check for movement and damp behind.Overtiling a wall that is damp, or a floor that flexes, hides the problem for a year and then fails twice as expensively. Fix the cause first or take the tiles off and see what is there.
- Key and prime the glazed surface.Glaze is designed to be non-absorbent and nothing bonds to it easily. Degrease thoroughly to remove soap, grease and limescale, then abrade or apply a proprietary tile primer suited to non-absorbent surfaces.
- Use an adhesive rated for tile-on-tile.Not every adhesive is. The data sheet will say whether the product is suitable for non-absorbent substrates, and that is the one to buy.
- Stagger the new joints away from the old.New joints landing directly over old ones concentrate any movement in the same line. Offsetting them spreads it.
- Reconsider if the existing tiles are heavily textured or embossed.The new adhesive cannot fill deep texture reliably, and voids are exactly what you are trying to avoid. Flat, glazed old tiles overtile well; heavily profiled ones do not.
Tips
- In a shower enclosure, overtiling leaves you with no way to inspect or improve the waterproofing behind. If the shower has ever leaked, take the tiles off.
- If you overtile a floor, deal with the door before you lay: it is far easier to take a door off and trim it than to discover the problem afterwards.
- The old grout does not need removing, but it does need to be sound. Rake out anything crumbling and make it good first.
- Overtiling changes where the sanitaryware sits relative to the wall — check the toilet, basin and bath still fit before committing.
Common mistakes
- Overtiling without tapping the existing tiles — The new tiles are bonded to the old ones. If the old ones are letting go, the whole assembly comes off together, and the failure is now twice as heavy and twice as expensive to put right.
- Overtiling a plasterboard wall with heavy tiles — Plasterboard has a stated maximum tile weight per square metre. Two layers of tile and two beds of adhesive can exceed it, and an overloaded board pulls away from the studs — sometimes suddenly.
- Tiling straight onto glaze without degreasing and priming — Bathroom tiles carry an invisible film of soap, body oils and limescale. Adhesive bonds to that film rather than to the tile, so the whole new surface has a weak plane running through it.
If it doesn't work
New tiles sounding hollow within weeks
Cause: Poor bond to the glaze, or old tiles debonding underneath — Fix: Take a tile off and see which interface failed. If it is the old tile letting go of the wall, the whole area needs stripping back.
Door will not close over the new floor
Cause: Build-up not allowed for — Fix: Take the door off and trim the bottom. Check the hinge positions and any fire door requirements before cutting; a fire door has limits on how much can come off.
Sockets and switches now sit below the tile surface
Cause: Extra thickness exceeded the box depth — Fix: The faceplates need spacers, or the boxes need packing forward. This is electrical work at the accessory — if you are not confident, get an electrician to reset them.
Questions people ask
Can I tile over tiles on a floor?
Sometimes, but floors are less forgiving than walls because the whole build-up gets taller and because floor tiles are loaded. Check the existing tiles are all solidly bonded, check the doors and thresholds, and check the floor structure can take the extra weight — a suspended timber floor with two layers of tile is a lot of dead load.
How many loose tiles is too many?
There is no exact number, but the question to ask is why they are loose. A couple of hollow tiles in an otherwise sound wall is a local defect. Hollow tiles scattered across the wall means the substrate or the original workmanship has failed generally, and nothing built on top of it will last.
Is it better to just remove them?
Usually yes, if you can face it. Removal lets you see and fix the substrate, keeps the build-up thin, and removes the risk of inheriting somebody else's bad bond. The reason people overtile is that removal often takes the plaster with it and turns a tiling job into a plastering job.