The short answer is yes. As long as the existing floor or wall tiles are free from cracks and does not retain moisture, you can lay your new tile over the current tiles. However, you must assess the condition of the exisitng tiles before you lay over it – this includes:
- Discoloured grout suggests there are water-absorption issues whereby trapped moisture is causing damage.
- If the tilers who completed the existing work did a poor job, overlaying tiles would result in a tiling finish that is not level.
Therefore, if any of these signs apply to your surface, you need to remove the existing tiles before tiling.