Use an angle grinder equipped with a diamond blade to score the old tile. Extra thickness when tiling around shower fittings.
For the sake of a few hours work i would take them off.
Can you install tile over tile in shower. Tile on tile or as i say it. After spreading a thin layer of thinset over the old tile install schluter kerdi membrane. One option is to install decorative ceramic tiles over the plastic shower base.
Don t worry if you do pull a bit of plaster when stripping the tiles as it s easy enough to replace. Learn the largest tile industry secret to remodel your bathroom for just 200 bucks and 1 days work. Consider the shower drain as well as any wall tiles when measuring and laying out for your new tiles.
Save money by putting in the ceramic tiles over the plastic base yourself using a few basic tools and supplies found at any hardware or home improvement store. As long as your tiles are clean level and firmly adhered to the subfloor then you can install new tiles on top of it. And it lasts for 20 years.
You will need to consider that since you are adding tile you are adding height to the floor. Tiling over tiles can make it awkward i e. If there are only a few loose tiles remove and clean.
Removing existing tile before installing new tile is recommended however sometimes old tile can be very difficult or almost impossible to remove. If your old ceramic tile is worn or dated you can lay new tile right over the old and avoid the huge job of tearing out the old tile. This creates a better bonding substrate for the latex modified thinset.
No matter why you want another look you can tile over existing tiles if the wall is sturdy and none of the old tiles is cracked or loose. But this assumes that the floor underneath is solid concrete and that there are no cracks in the existing tile indicating underlying problems in the concrete. If your tiles are in relatively good condition evenly placed without cracks and not appearing to retain any moisture then you can probably leave.
Professional craftsman can install ceramic tiles but hiring a professional is costly. Rough up the tile. If the original tile is still in excellent condition then it is possible to install tile over tile but the proper steps must be taken in order to complete the project correctly.
Lay the waterproofing membrane. The short answer is most likely yes. In fact pros do it all the time.