The walls of my house have standard cavities, but where the walls form the
bay windows, the cavity drops to zero, ie two stretcher bond leaves butted
together. This obviously contributes to poor heat retention.
I want to insulate inside with something thin (ie low mu value).
I will strip of the plaster first. What is my best option?

I think it is common to put some sort of vapour barrier on top of the
insulation. why? A normal wall does not need it. I'm thinking polystyrene,
then plasterboard screwed to brick, then skimmed and painted. mositure does
not penetrate a regular plastered and painted wall, does it? Why should it
in this case?

Any how, what is my best approach? I don't really want to spend loads on
state of the art insulation. A freind has suggested 'bubble wrap' as a
possibility.

--
Mike W

"VisionSet" wrote in message
...
The walls of my house have standard cavities, but where the walls form the
bay windows, the cavity drops to zero, ie two stretcher bond leaves butted
together. This obviously contributes to poor heat retention.
I want to insulate inside with something thin (ie low mu value).
I will strip of the plaster first. What is my best option?

Kingspan or Celotex. Very thin high insulation qualities.

I think it is common to put some
sort of vapour barrier on top of the
insulation. why?

To prevent condensation occurring inside the wall.

A normal wall does not need it. I'm thinking polystyrene,
then plasterboard screwed to brick, then
skimmed and painted. mositure does
not penetrate a regular plastered and
painted wall, does it?

Yep, it does,

Why should it
in this case?

Any how, what is my best approach?
I don't really want to spend loads on
state of the art insulation.

Cellotex or Kingspan between batons poly vapour barrier over and then
plasterboard. Quite easy.

A freind has suggested 'bubble wrap' as a
possibility.

Nah.

I think it is common to put some sort of vapour barrier on top of the
insulation. why?

Because as the vapour penetrates the wall, it gets colder and condenses out
within the insulation.

A normal wall does not need it. I'm thinking polystyrene,
then plasterboard screwed to brick, then skimmed and painted.

Think Kingspan/Celotex, which have twice the insulation value per thickness.
The vapour barrier can simply be foil that is preattached to either the
insulation or the plasterboard.

mositure does not penetrate a regular plastered and painted wall, does it?

Yup.

Why should it in this case?

Because it always does, unless stopped by a vapour barrier. An acrylic or
vinyl based emulsion and gypsum plaster have very little vapour resistance.
Oil based paints have some, but it isn't great. The reason problems occur
less frequently with a straight brick wall are (a) bricks don't care about
being wet as much as insulation and (b) they're so permeable, the vapour
often gets all the way through before condensing.

Any how, what is my best approach? I don't really want to spend loads on
state of the art insulation. A freind has suggested 'bubble wrap' as a
possibility.

Don't bother with second rate alternatives. One 20 quid sheet of celotex
will cover most of it, as much of the "wall" will be windows and not require
insulation.

Christian.

"Christian McArdle" wrote in message
t...


Don't bother with second rate alternatives. One 20 quid sheet of celotex
will cover most of it, as much of the "wall" will be windows and not
require
insulation.

Christian.

Thanks, that all made total sense.
I have looked at Celotex pdf before and found all the options pretty
confusing.
Do you know exactly which product I should use?
I guess I can choose the correct thickness from some web based mu calculator
given my other (cavity insulted) walls mu values. Though I do have a window
sill lip to come up to. The windows are all ceiling height, so it is just
the base.

--
Mike W

I guess I can choose the correct thickness from some web based mu
calculator
given my other (cavity insulted) walls mu values. Though I do have a
window
sill lip to come up to. The windows are all ceiling height, so it is just
the base.

As for thickness, this is likely to be determined by the space available,
rather than the insulation required. 50mm will kill any condensation
problems. More just gives you better energy efficiency. On such a small
area, the difference will be marginal.

Of course, if the BCO is involved, they might have more specific ideas.

Almost any Celotex/Kingspan product would be appropriate. Either the
insulation or the plasterboard should have foil attached. It doesn't matter
which. If space is tight, the insulation is available to special order with
vapour barrier and paper covering, avoiding the need for a layer of
plasterboard.

Christian.

"VisionSet" wrote in message ...
The walls of my house have standard cavities, but where the walls form the
bay windows, the cavity drops to zero, ie two stretcher bond leaves butted
together. This obviously contributes to poor heat retention.
I want to insulate inside with something thin (ie low mu value).
I will strip of the plaster first. What is my best option?

Have you considered leaving the wall untouched and paying the very
sligthly higher heating costs?

Seriously, how long will it take to reconver the costof doing this?
How many kWhr/year will you actually save by doing this?

R

Seriously, how long will it take to reconver the costof doing this?
How many kWhr/year will you actually save by doing this?

Whilst marginal on energy efficiency grounds, it can make a significant
difference to comfort, convection current promoted draughts and, in
particular, condensation.

Christian.

"Christian McArdle" wrote in message
. net...
Seriously, how long will it take to reconver the costof doing this?
How many kWhr/year will you actually save by doing this?

Whilst marginal on energy efficiency grounds, it can make a significant
difference to comfort, convection current promoted draughts and, in
particular, condensation.


Absolutely. I have a very inefficient house, external walls on 3 sides of
almost every room. Huge bay windows and single glazing.

Though I should do the glazing - that is extra expensive and I have nice
original georgian bar windows in good state of repair that I like.

The bays form running condensation with mould when unattended, no where else
does this.

--
Mike W

On Fri, 26 Nov 2004 09:30:52 -0000, a particular chimpanzee named
"Christian McArdle" randomly hit
the keyboard and produced:
reply to VisionSet:

I guess I can choose the correct thickness from some web based mu
calculator
given my other (cavity insulted) walls mu values. Though I do have a
window
sill lip to come up to. The windows are all ceiling height, so it is just
the base.

If your aim is to make a poor situation better, I wouldn't be too
worried about matching U-vaues. It's not going to make more than a
few Watt-hours difference per year.

Of course, if the BCO is involved, they might have more specific ideas.

As long as he doesn't make the heat loss any worse, the BCO wouldn't
be interested.
--
Hugo Nebula
'What you have to ask yourself is, "if no-one on the internet wants
a piece of this, just how far from the pack have you strayed?"'

"Hugo Nebula" abuse@localhost wrote in message
...
On Fri, 26 Nov 2004 09:30:52 -0000, a particular chimpanzee named
"Christian McArdle" randomly hit
the keyboard and produced:
reply to VisionSet:

I guess I can choose the correct thickness from some web based mu
calculator
given my other (cavity insulted) walls mu values. Though I do have a
window
sill lip to come up to. The windows are all ceiling height, so it is
just
the base.

If your aim is to make a poor situation better, I wouldn't be too
worried about matching U-vaues. It's not going to make more than a
few Watt-hours difference per year.

Of course, if the BCO is involved, they might have more specific ideas.

As long as he doesn't make the heat loss any worse, the BCO wouldn't
be interested.
--

25mm of high performing Celotex is the equivalent of a solid stone wall of
over 1 metre thick.

On Fri, 26 Nov 2004 20:24:03 +0000, IMM wrote:



As long as he doesn't make the heat loss any worse, the BCO wouldn't
be interested.
--

25mm of high performing Celotex is the equivalent of a solid stone wall of
over 1 metre thick.

Medieval Lord : How doth the north turret progress?
Medieval Mason: With new-fangled Celotex, it will fly up, sire!
ML : Bravo my man! Will it stand against all manner of siege engines?
MM : The makers say its equivalent, my Lord. Thy clerk read unto me the
parchment of specification in the market place.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html

Ed Sirett wrote:

25mm of high performing Celotex is the equivalent of a solid stone wall of
over 1 metre thick.


Medieval Lord : How doth the north turret progress?
Medieval Mason: With new-fangled Celotex, it will fly up, sire!
ML : Bravo my man! Will it stand against all manner of siege engines?
MM : The makers say its equivalent, my Lord. Thy clerk read unto me the
parchment of specification in the market place.

LOL

--
http://gymratz.co.uk - Best Gym Equipment & Bodybuilding Supplements UK.
http://trade-price-supplements.co.uk - TRADE PRICED SUPPLEMENTS for ALL!
http://fitness-equipment-uk.com - UK's No.1 Fitness Equipment Suppliers.
http://gymratz.co.uk/hot-seat.htm - Live web-cam! (sometimes)

"N. Thornton" wrote in message
m...

secondary glazing

Sealed units.


The bays form running condensation with mould when unattended, no where
else
does this.

dehumidifier

Cure the disease not the symptoms

--
Mike W

"Pet @ www.gymratz.co.uk" wrote in message
.uk...
Ed Sirett wrote:

25mm of high performing Celotex is the equivalent of a solid stone wall
of
over 1 metre thick.


Medieval Lord : How doth the north turret progress?
Medieval Mason: With new-fangled Celotex, it will fly up, sire!
ML : Bravo my man! Will it stand against all manner of siege
engines?
MM : The makers say its equivalent, my Lord. Thy clerk read unto me
the
parchment of specification in the market place.

LOL


ROFL!!! Love it.