I am currenly doing up a bathroom with one external wall, solid 9" brick with 1" plaster. The wall is around 2.5 x 2 metres area, and has one window 53 x 133 cm. I cannot decide it it is worth insulating the wall or not. The insulation if I do it will be 20mm celotex and 12mm aquapanel. I can remove 1" plaster on the window reveals to accomodate the celotex there. I cannot accomodate a thicker layer of celotex. The rather open question as I have it in my head - is this worth the trouble ? Simon.
Yes. It is particularly worth it in the bathroom, as it will substantially reduce condensation and, hence, mould. Even 20mm of Celotex will provide a very worthwhile improvement over a 9" wall.
I had a bathroom with a flat roof and two outside walls facing North and West and solid walls. It was aweful in the winter / cooler months for "feeling cold" ( it was) and the condensation was terrible.
A quick fix of that 3mm polystyrene wallpaper and then that "plastic coated" wallpaper over it made a huge difference although not completely eliminated the problems.
The 20mm celotex will be very well worth the trouble, both for reducing condenstaion and helping make the room feel warmer by keeping the wall surface temperature significantly higher than it currently is.
I would (and recently did) do this for condensation reasons as much as anything else, as others have said.
I would use wediboard or equivalent rather than celotex and aquapanel. One layer of material so it would be easier to fix (it can be dot and dabbed like plasterboard, with additional screws for security). What you lose in U-value (its polystyrene rather than polyisocyanurate) you'll mostly gain back in the extra 10mm or so of insulation you'll have, as the cement face on wedi is only 1mm thick either side. And it should work out cheaper than celotex and aquapanel, although it is a bit pricey.
Not heard of wedibacker before, so googled it. 1mm cement faces on poly foam, reckoned to be not very strong, and very expensive. Any screws need washers and cant be countersunk.
20.0mm Thick 250 x 90cm =A351.83 Thats 8' x 1' 6" in English.
So a 12' wall would be =A3414 for the wedi alone, with no allowance for damaged board.. Could make 4mm glass fibre reinforced cement board with rockwool insulation tufts stuck to it for a fraction of that. Dont know how long it would take to make 10 boards but =A3414 gives you a few days to do it, should be plenty.
Thanks for all the opinions folks. You've convinced me. I already have the celotex from a previous job, so I'll be using that with one or other of the reinforced cement boards you can get.=20 Simon.
I've replied a couple of times to this, but google seems to have swallowed them. All a bit irrelevant now, but for the archive I'll try again (not through google)
snipped-for-privacy@care2.com wrote: > Not heard of wedibacker before, so googled it. 1mm cement faces on poly
It is plenty strong - very stiff indeed. Maybe a bit prone to compression damage if you are careless enough to bash it with something sharp, but once tiles are on that is utterly irrelevant.
Any screws
Is that a criticism? The washers are cheap enough at about £6 for 50 (not much different from the cost of aquapanel screws)and the screws do countersink into the washer, which compresses into the face of the board.
Rubbish price - I got my 250cm x 60cm x 30mm boards for around £25.
You're using some long feet there. More like 8' x 3' in English.
I make it two of those 90cm boards for the OPs wall, assuming the window isn't being tiled, at £100 or so at the expensive price you found, or £75 or so at the price I got it for. Which (if the OP didn't have celotex for free) compares to 25ish for that, and £10ish a sheet for 4
120cm x 90cm sheets of aquapanel i.e £65. No battens and a lot less hassle, for a tenner extra.
Could make 4mm glass fibre reinforced cement board with
There is no way that would be as strong as the poly/cement sandwich. You'd need a polymer-modified tanking mix to match the wedi's waterproof performance (and they aren't cheap, at about £50 a bag). And it's mesh, not fibre, reinforced, so tougher. And it doesn't squish unevenly when you tighten it up against the wall. And you save a day or a few days work for what, £50?
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