Many bathrooms are already tiled and the big question is do I need to take off the existing tiles or can I tile straight on top of the old ones.
Well the answer is yes and no
There are adhesives on the market that will certainly stick to the existing tiles but that is not the only thing you have to consider.
The original tiles will be stuck to the background substrate but what is it, the problem with tiling on top of tiles is you don’t know what the original surface is.
If the original surface is made of plasterboard then this will have a weight ratio of 32kg/ mt2 which is ideal for holding two sets of tiles, however if the plasterboard has been skimmed with plaster, this will reduce the weight ratio down to 20kg/ mt2 which is not enough for two sets of tiles and therefore failure can happen.
Who has fixed them before?
Another problem with tiling on tile your tiles are only as strong as the last persons fixing.
If the last person who has fixed the tiles has used incorrect methods and the tiles are not fully bonded, the weight of your new tiles can pull the last tiles off the wall resulting in failure.
What is the condition of the surface?
With tile already being on the wall you have no idea what the condition of the surface is like, is there damp or cracks in the wall, both of these can lead to tile failure.
Around your doors you will have an architrave, when using one set of tiles this still looks good as the architrave will still sit proud of the set of tiles, once you load up with another set of tiles, the new set becomes flush with this architrave and looks terrible.
For safety and a good looking finish, it is best to remove all existing tiles from the wall, do a survey of what the state of the wall is and prepare it correctly, by doing this you are dramatically reducing the risk of failure.
By having the correct training by attending a tiling course you can do all your DIY projects with confidence.