Prep on walls masonry, stud, moistureboard and skimmed plaster

[reyplus]

I need help on what prep I need to do.

I have read on the forums here and I seem to be going round in circles. I have a small bathroom which is stripped back to the following.

wall 1 - masonry red brick
wall 2 - masonry red brick
wall 3 - part stud wall with top 1/4 moistureboard attached
wall 4 stud wall - moistureboard attached skimmed over



a) So the bathroom will sit between walls 1,2,3. Here I am going to board out with tile backer board from wickes. I called STS and they said to use dot and dab to fix the board onto the walls and then mechanical fixings into the wall where the dot/dabs are. To use standards S1 adhesive to dot dab. But to do the mechanical fixings straight awat and not after the adhesive has set.

To prepare the red masonry wall first I need to use a suitable primer? SBR neat or diluted? Or can I use the following from Toolstation - Mapei Plaster Primer

Mapei Plaster Primer

When carrying out tiling work in the bathroom or kitchen, use this Mapei plaster primer to treat surfaces before installing tiles to seal the walls. This handy product is water-based, so it's suitable for use on all porous backgrounds including plasterboard, plaster and render. It can also be...

www.toolstation.com

b) For the part stud wall - this will be boarded in the tile backer secured to the stud wall. But what prep do I need to do for the moistureboard?

c) wall 4 - will just have the sink and radiator attached. For some reason the plasterer skimmed over the wall. So its a stud wall with moisturebaord and skimmed. So what prep needs to be done here?

I am using wickes porcelain tiles that weigh 23kg.

I am having a showerbath fitted.

STS advised that the tilebacker board needs a beed of their STS glue on the edges so no need for tape or tanking on top.

 

[jleag]

So I have rung around and I think I will be going with the following unless someone advises against it.

Wall 1 - red brick. To prime with SBR 3:1 and leave for 30 mins before dot and dab the foam tile backer board.

Wall 3 - No prep requires can tile directly onto the moistureboard.

Wall 4 - to use Mapei primer G 1:1 - how long do you leave that?

As to Wall 4 which has skimmed plaster - the weight of my tiles is 23 kg m/2 plus grout and adhesive.

So should I use that as a feature wall and get different but lighter weight tiles?