Our bedroom is always cold at one end where there is a gable wall.
This wall has fitted wardrobes mounted in front of it. The house is
late 20's with cavity walls and the cavity is very well ventilated so
the inner wall I guess is pretty much at the ambient temperature. I'm
reluctant to fill the cavity with insulation as I don't want to end up
blocking the vents below the DPC and causing vapour condensation.

So, I'm looking at moving the front of the fitted wardrobes forward
and fixing insulation to the wall. I can readily spare the 2 to 4
inches of thickness that might be involved. . Someone suggested foil-
backed insulated plasterboard and this looks like an attractive
possibility as it wouldnt need to be skimmed because the wardrobes
span the full width/height of the wall.

I'd much appreciate guidance on how to proceed - whilst giving careful
consideration to vapour barriers, condensation etc -e.g. would I need
to leave an air gap? Should I fix it on to battens or screw direct on
to the wall? Would I need to seal all the joins and edges?

Vet Tech

In article <e35b8eb4-adb7-453c-a864-(E-Mail Removed)
..com>, Vet Tech <(E-Mail Removed)> scribeth thus
>Our bedroom is always cold at one end where there is a gable wall.
>This wall has fitted wardrobes mounted in front of it. The house is
>late 20's with cavity walls and the cavity is very well ventilated so
>the inner wall I guess is pretty much at the ambient temperature. I'm
>reluctant to fill the cavity with insulation as I don't want to end up
>blocking the vents below the DPC and causing vapour condensation.
>

Fill the cavity with blown wool insulation we has this done years ago
with no problems at all)


>So, I'm looking at moving the front of the fitted wardrobes forward
>and fixing insulation to the wall. I can readily spare the 2 to 4
>inches of thickness that might be involved. . Someone suggested foil-
>backed insulated plasterboard and this looks like an attractive
>possibility as it wouldnt need to be skimmed because the wardrobes
>span the full width/height of the wall.

Yes you could do that but the cavity fill will be a better bet..

And benefit the rest of the place too)..

>
>I'd much appreciate guidance on how to proceed - whilst giving careful
>consideration to vapour barriers, condensation etc -e.g. would I need
>to leave an air gap? Should I fix it on to battens or screw direct on
>to the wall? Would I need to seal all the joins and edges?
>
>Vet Tech
>

--
Tony Sayer

Vet Tech wrote:
> Our bedroom is always cold at one end where there is a gable wall.
> This wall has fitted wardrobes mounted in front of it. The house is
> late 20's with cavity walls and the cavity is very well ventilated so
> the inner wall I guess is pretty much at the ambient temperature. I'm
> reluctant to fill the cavity with insulation as I don't want to end up
> blocking the vents below the DPC and causing vapour condensation.
>

The vents below your DPC are usually underfloor vents, but it's all academic
anyway, whoever installs the CWI either replaces the vents (which is
included in the price) or otherwise makes sure they are clear after
installation, likewise any other vents, be they gas vents, room vents or
anything else...obviously cavity vents are sealed with silicone because they
will become defunct.

> So, I'm looking at moving the front of the fitted wardrobes forward
> and fixing insulation to the wall. I can readily spare the 2 to 4
> inches of thickness that might be involved. . Someone suggested foil-
> backed insulated plasterboard and this looks like an attractive
> possibility as it wouldnt need to be skimmed because the wardrobes
> span the full width/height of the wall.
>
> I'd much appreciate guidance on how to proceed - whilst giving careful
> consideration to vapour barriers, condensation etc -e.g. would I need
> to leave an air gap? Should I fix it on to battens or screw direct on
> to the wall? Would I need to seal all the joins and edges?
>
> Vet Tech

The amount you will spend on celotex, plasterboard, plaster and vapour
barriers, won't be far off the cost of CWI the full house.

partial grants are available through your energy supplier, or if you are
diabled or on benefits, 100% grants are available through the warmfront
scheme

--
Phil L
RSRL Tipster Of The Year 2008

> The amount you will spend on celotex, plasterboard, plaster and vapour
> barriers, won't be far off the cost of CWI the full house.
>
> partial grants are available through your energy supplier, or if you are
> diabled or on benefits, 100% grants are available through the warmfront
> scheme
>
> --
I'm still apprehensive about CWI based on previous posts to this NG -
particularly blocked air bricks and the number of cowboys in this
particular trade. I've queried a couple of authorised WarmFront
installers and got less than satisfactory answers. I'm in London and
am willing to reconsider CWI if someone recommends a thoroughly
professional installer.

Half my air bricks ( which vent the underfloor void ) are in a channel
around the house as the level of the rear patio and side alley is just
above the level of the air bricks. The previous owner of the house had
raised the levels and blocked the air bricks! Strange but true. As a
result, I had to replace the joists and floor boards in the kitchen
because of dry rot.
Hence I created the channel to expose the air bricks and hence my
sensitivity about blocked air bricks.

Given that the celotex/plaster board would be at back of the fitted
wardrobe, would it reallly be necessary to skim it?

Vet Tech

On 23 Jan, 18:34, Vet Tech <senditont...@gmail.com> wrote:
> > The amount you will spend on celotex, plasterboard, plaster and vapour
> > barriers, won't be far off the cost of CWI the full house.
>
> > partial grants are available through your energy supplier, or if you are
> > diabled or on benefits, 100% grants are available through the warmfront
> > scheme
>
> > --
>
> I'm still apprehensive about CWI based on previous posts to this NG -
> particularly blocked air bricks and the number of cowboys in this
> particular trade. I've queried a couple of authorised WarmFront
> installers and got less than satisfactory answers. I'm in London and
> am willing to reconsider CWI if someone recommends a thoroughly
> professional installer.
>
> Half my air bricks ( which vent the underfloor void ) are in a channel
> around the house as the level of the rear patio and side alley is just
> above the level of the air bricks. The previous owner of the house had
> raised the levels and blocked the air bricks! *Strange but true. *As a
> result, I had to replace the joists and floor boards in the kitchen
> because of dry rot.
> Hence I created the channel to expose the air bricks and hence my
> sensitivity about blocked air bricks.
>
> Given that the celotex/plaster board would be at back of the fitted
> wardrobe, would it reallly be necessary to skim it?
>
> Vet Tech

Dear Vet Tech

I have done this extensively and can advise with some authority and
experience.
Firstly, I would investigate the option to put blown mineral fibre
into the void because this is reversible if you have a problem. You
need to ensure that this is the case by written contract with the firm
and as you so rightly observe take precautions to ensure that the
channels to the subfloor air vents are protected by perhaps putting in
fittings of exendable plastic so it is ducted to the subfloor void and
separated from the cavity.
I am no expert in cavity walls so get better advice from others but as
far as I understand it the idea is not to vent the cavity other than
weep holes at the bottom so it is NOT at ambient outside temperature!

It is most unlikely that you got DRY rot from an absence of airbricks.
I have surveyed several thousand buildings many hundreds with dry rot
and NEVER ONCE found this to be the CAUSE. It is always a positive
source of water and not condensation or the like. It is a
contributory factor only when a postive source of water is present.

It was probably wet rot!

If it was dry rot then the cause was water not lack of ventialtion

On to the insualtion
If you are determined to insulate the gable from the inside (consider
outside) then this is the way I did it

I discounted the advice from the manufacturer to put on battens (too
much space taken up and not necessary for water penetration risk
through outside wall)
I used the pink plastic / stainless steel nails made for external
insualtion together with Plasterboard adhesive to fix 2" TP 10 (or any
PU board with foil on) to the wall surface ensuring it was sound
I then did the same with 1/2" plaster board
10 or so fixings - five in each layer
Glue put on a la a tile with tile trowel

Skip with plaserboard finish and Bob's your uncle

Problem is that to do the gable properly you need to
a) take off the skirtings, picture rail, cornice if present, lift
floor boards (hope not the wrong way otherwise its alternate staggered
cuts) and cut short on side walls
and
put them all back on the surface afterwards! This needs long fixings
to go thru insuationi into the masonry

Once done its warm as toast

Great!

Chris

On 22 Jan, 11:12, Vet Tech <senditont...@gmail.com> wrote:

> I'd much appreciate guidance on how to proceed

Read the Celotex website. They've a bunch of glossy guides on how to
do various sorts of refurb. Naturally they're fond of their own
products, but the information is good.

If you care about thickness, you're likely to spend extra to use the
yellow foam PIR boards rather than doing it cheaply with rockwool.
It's usually a couple of inches. Hacking the plaster off first gains
an inch.

Cavity wall is great, but only if you're 1950s+ or so, and you have a
usable cavity to work with.