Hi,

The front bedroom of our house is noticeable colder than the back
bedroom. I used to think this was because the rear of the house caught
the sun but we haven't had sun for some weeks so there must be more to
it than that.

The rear of the house (1970s) is brick with an insulated cavity and
breeze block inside. The front of the house is (I guess) breeze block
inside and then tiled cladding. Does the cladding do anything with
respect to trapping heat? Surely it is not airtight so in effect,
don't we have a single skin wall on the front of the house?

I think the best solution would be to remove the cladding and put
kingspan on the front of the house and then put the tiles (or
something prettier! - but what?) on top. However this might also be
expensive because I wouldn't be DIYing that.

I was wondering whether a good compromise would be to put kingspan on
the inside and plasterboard over that, at the expense of losing an
inch or two from the room's length? Can't you even get combined sheets
that are plasterboard pre-bonded to the insulation?

I'm not too good with u-values; what would be the best thickness of
kingspan to use?

The room has a big radiator but that only helps when the heating is
on. Is it worth running the front of the house on a separate zone to
the rear of the house?

TIA

On 8 Jan, 06:19, Fred wrote:
Hi,

The front bedroom of our house is noticeable colder than the back
bedroom. I used to think this was because the rear of the house caught
the sun but we haven't had sun for some weeks so there must be more to
it than that.

The rear of the house (1970s) is brick with an insulated cavity and
breeze block inside. The front of the house is (I guess) breeze block
inside and then tiled cladding. Does the cladding do anything with
respect to trapping heat? Surely it is not airtight so in effect,
don't we have a single skin wall on the front of the house?

I think the best solution would be to remove the cladding and put
kingspan on the front of the house and then put the tiles (or
something prettier! - but what?) on top. However this might also be
expensive because I wouldn't be DIYing that.

I was wondering whether a good compromise would be to put kingspan on
the inside and plasterboard over that, at the expense of losing an
inch or two from the room's length? Can't you even get combined sheets
that are plasterboard pre-bonded to the insulation?

I'm not too good with u-values; what would be the best thickness of
kingspan to use?

The room has a big radiator but that only helps when the heating is
on. Is it worth running the front of the house on a separate zone to
the rear of the house?

TIA

Dear TIA
The insulation needs to be "joined up" ... you have a bit of a problem
here
it would help if you were to have stated if the house is terraced,
detachted or semi
If it is terraced then it is probably worth insulating the whole of
the front but not unless you DIY as to have it done professionally you
will be dead before the pay back if ever
If it is detached then I would consider the internal route and if you
cannot diy the outside then go internally
I have done this with success in the past using 2" Kingspan attached
with plaster board glue to the walls supplemented by the plastic and
stainless steel 6" fixings for external Kingspan, followed by 3/8"
plaster board similarly (but with staggered fixings) fixed and then
skimmed with finish
It means taking off all architraves, skirtings etc and putting them
back on with special plaster board fixings
it means loss of 2.5" inside but hell it is really warm and worth
while

Chris

On 8 Jan, 06:19, Fred wrote:
Hi,

The front bedroom of our house is noticeable colder than the back
bedroom. I used to think this was because the rear of the house caught
the sun but we haven't had sun for some weeks so there must be more to
it than that.

The rear of the house (1970s) is brick with an insulated cavity and
breeze block inside. The front of the house is (I guess) breeze block
inside and then tiled cladding. Does the cladding do anything with
respect to trapping heat? Surely it is not airtight so in effect,
don't we have a single skin wall on the front of the house?

I think the best solution would be to remove the cladding and put
kingspan on the front of the house and then put the tiles (or
something prettier! - but what?) on top. However this might also be
expensive because I wouldn't be DIYing that.

I was wondering whether a good compromise would be to put kingspan on
the inside and plasterboard over that, at the expense of losing an
inch or two from the room's length? Can't you even get combined sheets
that are plasterboard pre-bonded to the insulation?

I'm not too good with u-values; what would be the best thickness of
kingspan to use?

The room has a big radiator but that only helps when the heating is
on. Is it worth running the front of the house on a separate zone to
the rear of the house?

TIA

Hi Fred.

Before you do anything further, it would be worth speaking to your
local council regarding advice for insulating your property.
Not sure which dept takes care of these issues but there are grants
available for certain types of property to improve energy
efficiency... they would likely be able to send someone round to you
to assess the situation and, even if you did not qualify for a grant,
they would definitely be able to help you, based on their experience
with similar properties in the area.

I've done a couple of jobs of this nature, here in Potters Bar, which
usually involves battening out the walls, friction fitting slabs of
Kingspan in between, covering with a vapour barrier and then tacking
up foil-backed wall board. Also retro-fitting trickle vents to pvc
window frames and installing de-humidifier fans and air bricks where
necessary... this is of course where condensation has been evident,
but you will also have a dew point going on somewhere, in your
property where the warm is meeting the cold!

HTH

deano.

Solar gain is worth 4oC by 10:30am where one room is South facing w/
bay windows, another North facing. After the sun has gone it goes into
reverse (-1oC difference).

Batten the walls. Friction fit 25-40-50mm celotex between the battens.
Cover with 25mm celotex to remove cold bridging. Fit plasterboard over
the top (or Marmox which has higher insulation but vastly higher cost
if you are desperate to squeeze in every last millimetre as being
insulatory). Thin 3mm skim with finishing plaster.

If the wall is solid, SBR the wall, then cement slurry for
waterproofing (Mapei keraflex which is a cementitious adhesive to
making your own cement slurry with SBR). SBR is obtainable from B&Q,
Screwfix and online suppliers - a waterproof version of PVA (you can
not use PVA as it is water soluble and will do nothing to seal the
wall). The aim of the wall surface waterproofing is to stop the dew
point moving out of the wall into the insulation anywhere. Solid walls
are not very waterproof, and absolutely not if single brick hence the
pebbledash or tile covering. Same goes for the blockwork & rubble
below many bay windows, that has an insulation value of about 2mm
polystyrene(!).


Dire thickness limitations can be solved by aerogel sheet, but it is
really too expensive still - best saved for extreme situations such as
tiny kitchens (limited space for 65mm PIR insulation) of very limited
wall area (re aerogel cost) but diabolically cold (solid double brick
with three external walls). In all other situations use PIR foam
(kingspan, recticel, celotex, a couple of other brands).

Please has anyone a link to the
[plastic and stainless steel 6" fixings for external Kingspan]
- do they solve cold bridging?
[g]


I have done this with success in the past using 2" Kingspan attached
with plaster board glue to the walls supplemented by the plastic and
stainless steel 6" fixings for external Kingspan, followed by 3/8"
plaster board similarly (but with staggered fixings) fixed and then
skimmed with finish

Chris

On Jan 8, 6:19*am, Fred wrote:
Hi,

The front bedroom of our house is noticeable colder than the back
bedroom. I used to think this was because the rear of the house caught
the sun but we haven't had sun for some weeks so there must be more to
it than that.

The rear of the house (1970s) is brick with an insulated cavity and
breeze block inside. The front of the house is (I guess) breeze block
inside and then tiled cladding. Does the cladding do anything with
respect to trapping heat? Surely it is not airtight so in effect,
don't we have a single skin wall on the front of the house?

I think the best solution would be to remove the cladding and put
kingspan on the front of the house and then put the tiles (or
something prettier! - but what?) on top. However this might also be
expensive because I wouldn't be DIYing that.

I was wondering whether a good compromise would be to put kingspan on
the inside and plasterboard over that, at the expense of losing an
inch or two from the room's length? Can't you even get combined sheets
that are plasterboard pre-bonded to the insulation?


yes, "thermaboard" i think it is called. You can look up how much you
need to get an acceptable U value and you can simply fix it by dabb
and dotting. We have this on a bedroom with solid walls and it made
a huge difference. Don't forget that if you change the U value of
the wall it is a building control matter and you have to bring it
right up to present standards (part L).


Robert

... or Kingspan "Kooltherm K17" he

http://www.insulation.kingspan.com/uk/k17.htm

Robert

On 8 Jan, 06:19, Fred wrote:
I think the best solution would be to remove the cladding and put
kingspan on the front of the house and then put the tiles on top.

Sounds best. In general, insulating outside the main wall is better
than insulating inside it, but it's often not an option. If it is,
then go for it.

Retro-fit insulation is also an art of finding good compromises. You
don't want to spend more in capital than is justified by the savings
plus the comfort benefits. For this reason your retrofit probably will
involve cold bridges that you'd work harder to avoid in a new build.
Nor is a cold bridge as bad as all that - it reduces efficiency, it
doesn't stop insulation working altogether.

I'm not too good with u-values; what would be the best thickness of
kingspan to use?

Celotex website. Lots of really good example case studies of what to
do to solve particular problems, and which products will deliver how
much saving.

There are also good U value explanations around. It's really worth
understanding this.

IMHE, you have to get to the level of estimating areas involved, doing
the U value calculations, then the resultant heat loss calculations,
then doing a damned great spreadsheet to compare the benefits with or
without the expensive cold bridge solution, or thinner insulation vs.
losing 2" off the room internal space. This stuff isn't trivial, but
at least the arithmetic is simple enough.

On 8 Jan, 11:52, "js.b1" wrote:
Solar gain is worth 4oC by 10:30am where one room is South facing w/
bay windows, another North facing. After the sun has gone it goes into
reverse (-1oC difference).

Batten the walls. Friction fit 25-40-50mm celotex between the battens.
Cover with 25mm celotex to remove cold bridging. Fit plasterboard over
the top (or Marmox which has higher insulation but vastly higher cost
if you are desperate to squeeze in every last millimetre as being
insulatory). Thin 3mm skim with finishing plaster.

If the wall is solid, SBR the wall, then cement slurry for
waterproofing (Mapei keraflex which is a cementitious adhesive to
making your own cement slurry with SBR). SBR is obtainable from B&Q,
Screwfix and online suppliers - a waterproof version of PVA (you can
not use PVA as it is water soluble and will do nothing to seal the
wall). The aim of the wall surface waterproofing is to stop the dew
point moving out of the wall into the insulation anywhere. Solid walls
are not very waterproof, and absolutely not if single brick hence the
pebbledash or tile covering. Same goes for the blockwork & rubble
below many bay windows, that has an insulation value of about 2mm
polystyrene(!).

Dire thickness limitations can be solved by aerogel sheet, but it is
really too expensive still - best saved for extreme situations such as
tiny kitchens (limited space for 65mm PIR insulation) of very limited
wall area (re aerogel cost) but diabolically cold (solid double brick
with three external walls). In all other situations use PIR foam
(kingspan, recticel, celotex, a couple of other brands).

Doesn't the foil on the celotex act as a vapour barrier? do you really
have to waterproof the surface of the wall with cement slurry as well?
I was hoping to get away with just dabbing thermobard to the wall in
my flat which has 9" solid walls and outside render but now you've got
me wondering.

On Jan 8, 7:05*pm, Rednadnerb wrote:
Doesn't the foil on the celotex act as a vapour barrier?

Yes, to you breathing in the room.

However against the outside wall (which I think you said was single
brick with tiles) moisture can still condense out in the interstitial
space between the foil & wall. It is how wooden battens can rot and
dot-n-dab adhesive fails.

Cement slurry is only a bucket of runny quick setting cement, nothing
magical, takes a few minutes.


I was hoping to get away with just dabbing thermobard to the wall in
my flat which has 9" solid walls and outside render but now you've got
me wondering.

If you telephone the various suppliers they will not suggest dot-n-dab
on solid wall (eg, not suggest dot-n-dab with K17), but will on a
cavity wall (eg, less chance of moisture bridging). When I telephone
Lafarge re Insulated Plasterboard the first question was whether the
wall was cavity or solid, when I said solid they said they would not
recommend dot-n-dab but mechanical fixing only (wooden battens).