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Second story bathroom, external double skin brick on three sides. What is the best way to insulate onto this, insulation backed plasterboard (I'm using non-organic type board around the shower) or stud and loft insulation?
What's the most cost effective whilst giving a decent performance benefit?
Yes. See recent thread here ( there are also older ones that can be searched):
https://singletrackmag.com/forum/topic/internal-wall-insulation/
IMO worthwhile.
My tips are look at Kingspan and Celotex websites for how to fit.
Rockwool is about half the insulation per thickness of phenolic foam so they are the norm for internal walls. I did insulated plasterboard onto battens. Effectively dry lining with extra thick board. Made the bathroom cosy rather than freezing.
when you say double brick is it a cavity wall?
I stuck celotex on the walls with soudal foam and then plasterboard on top with the same foam, much cheaper than the stuff already stuck and much less messy than dot n dab mix.
Oh and 9mm taper edge plasterboard, much easier to handle and you don't have to skim, just the joins.
However in a bathroom I think I would skim.
No cavity, just two courses of bricks side by side, it's an old 1900's terrace.
Thanks both, was planning on skimming the lot apart from the section around the shower where I'll tile. I'll take a look at these suggestions.
If it's a solid masonry wall then generally it'll be a brick thick wall. 😉 So broadly approximately 215mm/ 225mm thick.
Double brick would be about 450mm thick but then you'd have a castle.
We have the same.
Stripped old plaster, to let the walls breathe, batoned and used insulated plaster.
Vented the gap to floor boards above and didn’t seal the bottom.
The idea is to allow air to circulate to keep the damp down.
Four years in its working.
We now have a badly built flat roof extension that needs external insulation and roof insulation.