bathroom wall tiling question (yes another one )

Hi All

Everybody seams to be having fun in the bathroom and I am about to join you

The scene
Location :- tiling around the bath side and one end ( shower over bath )
Wall :- Concrete block with 3/4" cement render ( well some sort of concrete stuff) with tiling on top built mid 70's

What I would like to do :- Remove all tiles
At the moment there is a step at the end so tiles overlap lip of bath
I want to pack this out to make it flat using a sheet fibro ?
Also using more fibro make a pack out on the wall to extend the tile area up for a width of 3 150x150mm tiles

Question what is the best way to attach the fibro to the wall and cememt render, or is this a bad idea, or is there another way...

Many thanks Don

Maybe another glass of red will be a good idea

If I understand you, the bathroom has concrete walls and where the shower/bath is, there is a 3/4" mortar bed and the wall tiles on that? If that's the case ,these things can be like bomb shelters. You may get the tiles off, but equally likely you will have a wall with tile fragments still stuck to it, or you may destroy the integrity of the mortar bed, necessitating its removal too. That can be, um, akward since it is probably reinforced with metal lath. I have painful memories of demoing one of these with a diamond blade and cold chisel and dust so thick the opposite wall as not visible - thank heavens for the respirator. On the other hand you can't very well add another layer of tiles over the old ones. To pack out the wall where you want to add the extra rows of tiles you could either extend the mortar bed up, screw on 3/4" compressed flooring into wall plugs or if it is not in an area that is wet, you could probably get away with 3/4" structural ply, very well sealed on all faces and screwed down.
Sorry I can't picture the bath lip setup, could you get a digi photo?

Cheers
Michael