Can you tile over existing tiles?

Yes, you can tile over existing tiles in many situations, but it depends on the condition of what is already there. The old tiles must be firmly bonded to the wall or floor with no hollow or loose areas. Tap them with your knuckle — if they sound hollow, they need to come off. You also need to check that the extra thickness will not cause problems with door frames, skirting boards, or shower trays. On a floor, the combined weight of two layers of tiles must be within what the subfloor can support.

The key to tiling over tiles is surface preparation. I always sand the glaze off the existing tiles with a coarse diamond pad and then apply a coat of tile primer before fixing. Without this step the adhesive cannot grip properly and the new tiles will eventually lift. I would not recommend tiling over tiles in a shower enclosure because moisture can get trapped between the two layers and cause problems over time. In those areas I always strip back to the substrate and apply tanking membrane before tiling.

From a cost perspective, tiling over tiles saves money on strip-out and waste disposal, which can be £300 to £600 in a typical bathroom. However, if the existing tiles are cracked, uneven, or on a suspect wall, you will spend more fixing problems later than you save now. I always tell clients that a proper strip-back and fresh substrate gives a better long-term result. If budget is tight and the existing tiles are in genuinely good condition, overlaying is a reasonable compromise for a kitchen splashback or utility room floor.