Plasterboard onto render?

[beatts]

HI

I've just removed all of the tiles from my bathroom walls.

The plasterboard walls are still ok (badly secured tiles) and so am not concerned about these, however on the blockwork walls I have ended up pulling most of the skim coat off with the tiles.

I am now left with the base render which I think is sand / cement mix as it is quite soft and powdery.

Can I dot n dab plasterboard directly to this render or does it need to be skimmed over first??

I would rather use plasterboard if I can due to it giving me a nice flat surface to tile back onto, also it will be stronger than a 3mm skim coat


many thanks in advance

 

[roughcaster]

If it was me, and there was room to do it, I would strap the wall with 2"x1", and fix the plasterboard to that... There's a fair bit of weight in plasterboard, and if it was dabbed onto a surface that was soft and powdery, plus the weight of the tiles, it might be a bit much. If you did dab it on, and used some form of mechanical fix too, say, plugs and screws, then that would make for a much stronger job. Just make sure there's plenty of support between the joints, (where the boards join).

Roughcaster

 

[Richard C]

A difficult call with out seeing it but if the render base is powdery & breaking down, I wouldn’t risk either re-skimming or dot & dabbing PB over it. You could batten out as RC suggests but if it’s that bad, I would strip it back (messy but probably not that difficult) & either re-plaster the lot with a base coat, finish & then tile or dot & dab with PB & skim that.

If you go with PB, make sure to use water resistant not ordinary wall board & in wet areas (behind bath & in showers) either tank it out or use a cement based backer board (Aquapanel or similar) or you’ll probably be doing it again in another couple of years time.