Tiling over old tiles

Lemoncurd

Is tiling over old tiles considered to be acceptable practice?

I suspect it isn't but I've seen it done quite often before so wasn't sure. We've just put in an offer on a house which has a "refitted" ensuite.... except they haven't finished it. It is obvious that they've tiled over the old tiles and badly because they are uneven and there are huge gaps in the corners of the room.
If we were to get the house we're not sure whether it would be best to try and make the best of it or get the professionals in and completely redo it. It has a large shower cubicle so one of the main concerns is that it might leak if there were any problems before.

plumb1_2

It is acceptable to tile over tiles,as long as they are sound and not loose etc,and you will have to de-grease and prime the tiles 1st.
But what you describe uneven and gaps and shower area,you are best to hack off and start again.Depends on how bad the walls are.

Baz_Bee_2

As plumb1 says tiling over old tiles is perfectly acceptable as long as the old tiling is sound and even. Again as said by plumb1 the old tiles should be thoroughly clenaed and then primed with unibond or similar to give a good base for the new tile adhesive.

I partly hacked off and partly tiled over existing in my bathroom and I defy anyone to tell which area is which.