help please with bathroom wall

[finnlou]

Please forgive me if this has been asked/resolved before but i am a noob to this site. I am refurbishing my bathroom and when removing the old tiles most of the plaster has come with them, by the look of it the plaster was as old as the house (1920's) and the small amount of plaster that remained was so crumbly i thought it best to remove it all back to the bare brick. i am fixing marmox waterproof insulation boards from floor to ceiling of 3 walls and tiling over these as i am creating a wet-room in one corner, but on the remaining wall that the bath and sink will be, i want the first metre from the floor up tiling and the rest plastered so i can paint it. My question is, will dob and dab plasterboards be strong enough to support these tiles, which will probably be quite heavy natural stone ones, or would the plasterboard want fixing to batons or would it be better just plastered by hand? The walls are quite uneven. Any advice will be much appreciated cheers.

 

[Micilin]

IMO, the best solution would be sand and cement render onto the brickwork, skimmed and tiled.It will take any tile, and it will not be affected by damp like plasterboard , bonding , timber etc

 

[trowelmonkey1]

agree with micilin as to the best option BUT if you are determined to have board then use green moisture resistant stuff, from memory 12.5 mm plasterboard takes about 25kg of weight per square metre so depends how heavy your tiles are.

 

[Richard C]

The render base Micilin & TMrecommends is the traditional approach & one I would normally go with but your building a wet room. I don’t really understand that having gone to all the trouble & expense of fitting Marmox on the other walls (I hope your tanking the joints!), you want to penny pinch on that 4th wall; it’s a wet room do your really want to risk it?

Plasterboard will support up to 32 kg/sqm if you stick them direct onto the base but a plaster skim reduces that to 20kg/sqm, including adhesive & grout. If you use PB, it must be Moisture Resistant & I would tank the bit under the tiles but the bit you want to skim must also be primed before hand or the skim won't stick.

 

[finnlou]

First, thankyou all for the rapid response to my dilemma and the great advice. I wasnt sure if you could plaster over marmox to create a cosmetically paintable surface, if this is the case i would rather marmox that wall as well as i will be using adhesive as well as mechanical fixings to attach it to the walls. I know marmox can withstand reasonably heavy tiles so this seems like it solves all my problems especially the uneven walls. I stick the tiles to the bottom half of the marmox and skim the top half. Would the marmox skim like plasterboard, same preperation etc?
Cheers once again

 

[Richard C]

Yes you can skim Marmox with the usual prep. Rather than skim up from the tiles after they are laid, skim the top half & waste it down into the area you’re going to tile (about 100mm), finished job look s much better.