Cement board on plastered solid wall

[rhysjc]

Hi all,

Kicking off our bathroom refit soon and struggling to get a conclusive answer on this. The bathroom is blockwork on all four walls, plastered and painted. I’m planning to overboard with cement board (probably Hardiebacker) but not clear on the best way to go about it.

Instructions suggest three beads of cartridge adhesive followed by brown plugs and 60mm screws. I was surprised by this as I’ve only ever read about these boards being dot and dabbed, left to set and then mechanically fixed. Not sure what the right way to about it is?

That aside, is there any prep I need to do to the existing wall surface? Either keying up the paint or priming it?

 

[robinbanks]

Are the walls well insulated?

 

[rhysjc]

@robinbanks it’s a cavity wall but no cavity insulation far as I know. It’s a very small room, don’t have the space to batten out and fix the boards to studs

 

[foxhole]

What do you hope to achieve by adding boards?

 

[rhysjc]

To increase the weight bearing capacity of the wall and also another layer of water resistance. Currently it’s just plaster on blockwork, which doesn’t take much weight.