Correct tanking choice for render and aquapanel bath area - TilersForums.com

[Stooby]

Hi, I'm new here, hope someone could give me some guidance.
I'm ripping out the bathroom in my 1930's semi, and will be tiling (undecided what type at the moment but assume large) and will be putting in studwork to conceaol the mixer shower pipework.
I'm pretty much decided on hardibacker for the studwork but I'm unsure what to do about the tanking for both the hardiback and the wall running along the bath.
The wall is sound in some parts, bad in others, looks to be sand/cement render on the brick with skim over. As a lot of it hishollow and won't hold tiles I'm going to re-render.
My question is, do I need to tank the render prior to tiling, or is it just a case of using whatever primer the adheshive manufacturer recommends?
I'm thinking of using Mapei or Dunlop/BAL adheshives if it helps. If I do have to treat the rendered wall can the same product also be used on the hardibacker?
Sorry if these are daft questions, I've been doing a lot of searching and suffering from information overload, not sure what the best route is.

 

[DHTiling]

Firstly Hello and welcome..

We could really do with knowing what you are going to install as to whether we could advise dot and dabbing plasterboard in the other area's..

 

[Stooby]

Hi Dave.

I know dot dab is the popular choice these days, but wouldn't that mean I would have to use more backerboard all over the wall or do you mean regular 12.5mm plasterboard?

I prefer the solidity of render on these bricks; mainly because the walls in this house are shocking and feel it would help strengthen the walls.... Last time I uncovered the brickwork I was surprised to find the walls had been built using rat-trap bonding on the upper-half of the house. :yikes:

 

[doug boardley]

sand and cement render (unskimmed) is an ideal substrate to tile onto stooby, as long as it's in sound condition, and when using cement based adhesives (bagged powder) does not need priming as long as it's dust free

 

[White Room]

Hi Dave.

I know dot dab is the popular choice these days, but wouldn't that mean I would have to use more backerboard all over the wall or do you mean regular 12.5mm plasterboard?

I prefer the solidity of render on these bricks; mainly because the walls in this house are shocking and feel it would help strengthen the walls.... Last time I uncovered the brickwork I was surprised to find the walls had been built using rat-trap bonding on the upper-half of the house. :yikes:

If the brickwork moves the render will crack which in turn will follow through to the tiles, the reason for dry linning in most propertys is the method of building, light weight block which had a tendercy to move/crack but would'nt show through the finished work.

 

[Stooby]

Thanks, I wondered if this might be the case, even if I add plasticiser to the mix?

If I used dot and dab what type of board and coating should I put on to accept tiles?

 

[Stooby]

Thought I'd post some pics to help. New bath will be going along this wall where the toilet and sink are at the moment. Plumbing for shower will be put up the wall on the right.

You can see from the pics the wall on the right is built with a mix of studwork, brick and render (I expect this is why we get problems with cracks in this house). The long back wall is the cavity wall with hollow plaster ontop of render (mainly around the bit where the lovely bright green colour is but really the whole wall can't be trusted IMO).

Having read the above replies I'm fast coming round to the idea of building studwork all around this area instead of spending days chopping the render out.

I know I'll lose space but it would have to be boarded with aquapanel anyways.
If it were you guys, would you just fix battens (with plugs drilled through to the brick) to these walls followed by aquapanel screwed on? (I hear aqua can't be dot and dabbed ) ?