Preparing for tiles - Tile Advice

[Amanda88]

Hi, I'm getting a lot of mixed advice and was wondering what the right thing for long lasting tiles. The old tiles have all been removed and trying to arrange the walls for the new tiles. The tiler has said he will tile straight onto the wall, the builder is saying plaster and the electrician is saying dot & dab boards. I'm going to be using 80 x 80 porcelain tiles so was wondering about the weight of the tiles with dot & dab. These are the pictures of the walls.Please advice as so confused.

 

[Dave]

You can’t tile straight onto that with heavy tiles.
do you have the room to overboard ?