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.

The rather open question as I have it in my head - is this worth the
trouble ?

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.

Christian.

sm_jamieson wrote:
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.

I would say yes.

If only to remove condensation opportunities

I rented a place with a bathroom with a wall like that, and in winter it
dripped condensation all the time.

Christian McArdle wrote:
The rather open question as I have it in my head - is this worth the
trouble ?

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.

Christian.


Even 4mm of cork stops condensation....

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 agree with the others - go for it....

Nick

sm_jamieson wrote:
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..

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.

wrote:
wrote:
sm_jamieson wrote:

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..

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 £51.83
Thats 8' x 1' 6" in English.

So a 12' wall would be £414 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 £414 gives you a few days
to do it, should be plenty.


NT

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.
Simon.

"sm_jamieson" wrote in message
ups.com...
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.

Well worth doing. It will keep condensation off the walls and keep the
bathroom warmer and cheaper to run in fuel.

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)

wrote:
Not heard of wedibacker before, so googled it. 1mm cement faces on poly
foam, reckoned to be not very strong, and very expensive.

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
need washers and cant be countersunk.

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.


20.0mm Thick 250 x 90cm £51.83

Rubbish price - I got my 250cm x 60cm x 30mm boards for around £25.


Thats 8' x 1' 6" in English.

You're using some long feet there. More like 8' x 3' in English.


So a 12' wall would be £414 for the wedi alone, with no allowance for
damaged board..

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
rockwool insulation tufts stuck to it for a fraction of that. Dont know
how long it would take to make 10 boards but £414 gives you a few days
to do it, should be plenty.

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?