Step 1 clean and prepare the tile floor.
Tiling over existing shower floor tiles.
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.
Laying a new layer of tile over the existing shower floor can solve these issues without removing the old tile and grout.
If you expect to apply an epoxy coating then you need to get the finish to a point where it can accept the coating.
Removing existing tile before installing new tile is recommended however sometimes old tile can be very difficult or almost impossible to remove.
The bad cuts can turn an otherwise good looking tile floor into an amateurish looking maintenance nightmare.
If the existing shower is correctly installed there is no way that the tiles on the floor of the shower can be level as pitch from the walls to the drain is required for the water to drain.
You do not have to allot work hours to pull up the existing tiles which means the tiling work can be finished much faster and all without the big mess.
Available at stores like home depot and lowes these peel and stick tiles are available for less than 1 a square foot.
Tile on tile or as i say it.
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.
Tiling over tile is usually a much easier and cheaper solution than pulling up your original tiles and re tiling your floor or wall.
Tile is covered with a smooth finish that prevents anything from getting through to the surface.
Many shower floors have cut tile with sharp or rough looking edges.
And it lasts for 20 years.
As much as i dispise pre mixed thinset for any application as a tile professional for 15 years i must strongly advise you to not give out advice to.
So first sweep the floor clean it with soap and water and allow it to dry.
Tiling over an uneven surface will give you less than stellar results so level out any globs of dried grout with a sander and secure loose tiles with fresh tile adhesive before beginning the project.
One advantage of doing this is that it is time saving.
In fact pros do it all the time.