Bathroom insulation

[Vaultedceilingguy]

Hi there, I'm renovating my bathroom and would like some advice. My bathroom is in a small original upstairs extension on the back of a terraced house. Two of the walls are exterior. It's those two walls I need advice for.

As one has a cavity, and the other doesn't, and as I don't really want to put cavity wall insulation in (it's a 1910 house and who knows what the cavity is like), I want to use insulated tile backer board on those two walls. One wall contains a free-standing bath + water pressure overhead shower, the other a toilet+sink.

So my plan is to remove the old plaster and expose all the brick on those walls, install the board, and tile over. I won't be going all the way to the ceiling on one of the walls because it's 10 feet at the high point and would look silly. Are these boards ok to plaster over if not tiled? Using one product would save a bit of money.

There are many backer boards on the market and I'm not sure which to choose. I want a good depth of insulation (at least an inch would be nice and wouldn't take much interior space). Can someone recommend a product? And should such products be bonded directly to the wall with adhesive, or should they be screwed into battens on the wall?

 

[motorbiking]

I would explore, celotex on the outside facing internal walls, moisture risirstenant plaster board to the ceiling and cement board in the wet areas. Given the cost of backer board, this might work out cheaper. It can all be fixed with some plasterboard foam and a few frame fixers. Depending on the depth of the "plaster" (caution its probably lime, sand and horse hair, make sure you protect yourself). You can go for somewhere between 25mm and 40mm (celotex) will actually make a difference to the U value, where as 10mm foam on a backer board wont.

 

[Deleted member 292770]

Are these boards ok to plaster over if not tiled?

Thermal insulated plasterboard may be better.