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Old November 16th 08, 05:46 PM posted to uk.d-i-y
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Default Cavity wall insulation

I thought that all modern houses had to have cavity wall insulation.

However my neighbour has found that their 8 year old house does not
have cavity wall insulation. Apparently the builders (Redrow) were
able to get away with using just thermalite blocks and no cavity wall
insulation.

We are now planning to have the insulation installed, but what were
the regs 8 years ago and should Redrow have been allowed to get away
with not installing cavity wall insulation?

Incidently we thought the house was a bit cold and the heating bills
high.

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Old November 16th 08, 07:20 PM posted to uk.d-i-y
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Default Cavity wall insulation

chudford wrote:
I thought that all modern houses had to have cavity wall insulation.

However my neighbour has found that their 8 year old house does not
have cavity wall insulation. Apparently the builders (Redrow) were
able to get away with using just thermalite blocks and no cavity wall
insulation.

We are now planning to have the insulation installed, but what were
the regs 8 years ago and should Redrow have been allowed to get away
with not installing cavity wall insulation?

Incidently we thought the house was a bit cold and the heating bills
high.


There has never been a requirement to install CWI on any building - the only
requirement is that the wall must meet certain levels of heat retention,
this can be acheived by using thicker thermalite blocks and having them dry
lined.

I'll wager that the walls in your house are about 350mm wide - 100mm outside
brick, 75mm cavity and 150mm inside block...the reamaining 25mm will be
drylining.

Why housebuilders go down this route is beyond me - the cost of the thicker
blocks far outweighs the price of having regular blocks and CWI


--
Phil L
RSRL Tipster Of The Year 2008


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Old November 16th 08, 07:26 PM posted to uk.d-i-y
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Default Cavity wall insulation

chudford wrote:
I thought that all modern houses had to have cavity wall insulation.

However my neighbour has found that their 8 year old house does not
have cavity wall insulation. Apparently the builders (Redrow) were
able to get away with using just thermalite blocks and no cavity wall
insulation.

We are now planning to have the insulation installed, but what were
the regs 8 years ago and should Redrow have been allowed to get away
with not installing cavity wall insulation?

Incidently we thought the house was a bit cold and the heating bills
high.


Looking on the good side, you can now upgrade the insulation further with
CWI, where as, if they had just put this in, and not used the thicker
thermalite blocks, then upgrading the insulation would have been more
expensive and more disruptive, so really they have done you a favor :-)

Toby...

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Old November 16th 08, 07:27 PM posted to uk.d-i-y
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Default Cavity wall insulation

chudford wrote:
I thought that all modern houses had to have cavity wall insulation.

However my neighbour has found that their 8 year old house does not
have cavity wall insulation. Apparently the builders (Redrow) were
able to get away with using just thermalite blocks and no cavity wall
insulation.

We are now planning to have the insulation installed, but what were
the regs 8 years ago and should Redrow have been allowed to get away
with not installing cavity wall insulation?

Incidently we thought the house was a bit cold and the heating bills
high.

I have a 10 yr old Rerow home , again without cavity wall insulation.
The construction is, as you say, themalite block but also with dry
lining. This was apparently good enough for the regs at the time. As
an aside, if you hve small bore heating, the pipes come down the wall
between the plasterboard and the blocks, sometimes in the corner of the
room.

Malcolm
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Old November 16th 08, 10:11 PM posted to uk.d-i-y
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Default Cavity wall insulation

On Sun, 16 Nov 2008 19:20:28 GMT Phil L wrote :
Why housebuilders go down this route is beyond me - the cost of the thicker
blocks far outweighs the price of having regular blocks and CWI


IIRC the NHBC do not allow CWI in some exposed areas

--
Tony Bryer, 'Software to build on' from Greentram
www.superbeam.co.uk www.superbeam.com www.greentram.com



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Old November 17th 08, 09:53 AM posted to uk.d-i-y
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Default Cavity wall insulation


"Malcolm" wrote in message
news
chudford wrote:
I thought that all modern houses had to have cavity wall insulation.

However my neighbour has found that their 8 year old house does not
have cavity wall insulation. Apparently the builders (Redrow) were
able to get away with using just thermalite blocks and no cavity wall
insulation.

We are now planning to have the insulation installed, but what were
the regs 8 years ago and should Redrow have been allowed to get away
with not installing cavity wall insulation?

Incidently we thought the house was a bit cold and the heating bills
high.

I have a 10 yr old Rerow home , again without cavity wall insulation. The
construction is, as you say, themalite block but also with dry lining.
This was apparently good enough for the regs at the time. As an aside, if
you hve small bore heating, the pipes come down the wall between the
plasterboard and the blocks, sometimes in the corner of the room.

Malcolm


How can you tell if a house has CWI? I have a 2001 build (Permisson, I
think) house. How would one tell if it has CWI?


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Old November 17th 08, 05:32 PM posted to uk.d-i-y
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Default Cavity wall insulation

Slider wrote:

How can you tell if a house has CWI? I have a 2001 build (Permisson,
I think) house. How would one tell if it has CWI?


drill a hole in the cement joint and have a poke around.
The hole only needs to be about 5mm diameter, but obviously 100mm deep, and
poke in a piece of wire, a straightened coathanger preferably, and if
there's any sponginess, it's insulated with yellow fibreglass batts, if
there isn't, it may still be insulated with loose fill fibreglass, and to
check for this, add a bit of gob oil to the end of the wire and have another
poke, fibreglass will be white, rockwool will be cement coloured.
If it's insulated with polystyrene or celotex type rigid foam, you should be
able to push the wire into it and you can 'feel' the sqeakiness of it as the
wire goes through, if that makes sense.

I'll wager a pound to a piece of dogturd that it's done with white blowing
wool - I used to do Persimmon homes every Saturday morning for years, and we
used white fibre,.

--
Phil L
RSRL Tipster Of The Year 2008


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Old November 18th 08, 09:22 AM posted to uk.d-i-y
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Default Cavity wall insulation


"Phil L" wrote in message
om...
Slider wrote:

How can you tell if a house has CWI? I have a 2001 build (Permisson,
I think) house. How would one tell if it has CWI?


drill a hole in the cement joint and have a poke around.
The hole only needs to be about 5mm diameter, but obviously 100mm deep,
and poke in a piece of wire, a straightened coathanger preferably, and if
there's any sponginess, it's insulated with yellow fibreglass batts, if
there isn't, it may still be insulated with loose fill fibreglass, and to
check for this, add a bit of gob oil to the end of the wire and have
another poke, fibreglass will be white, rockwool will be cement coloured.
If it's insulated with polystyrene or celotex type rigid foam, you should
be able to push the wire into it and you can 'feel' the sqeakiness of it
as the wire goes through, if that makes sense.

I'll wager a pound to a piece of dogturd that it's done with white blowing
wool - I used to do Persimmon homes every Saturday morning for years, and
we used white fibre,.

--
Phil L
RSRL Tipster Of The Year 2008


Thanks for the reply. Actually I was wrong with Persimmon, it was built by
Alfted McAlpine. Have you any experience of these?


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Old November 18th 08, 08:41 PM posted to uk.d-i-y
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Default Cavity wall insulation

Slider wrote:


Thanks for the reply. Actually I was wrong with Persimmon, it was
built by Alfted McAlpine. Have you any experience of these?


No.
McAlpine, and Barratt come to think of it, were never on our list of new
build sites.
This doesn't mean it isn't insulated though.


--
Phil L
RSRL Tipster Of The Year 2008


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Old November 18th 08, 11:56 PM posted to uk.d-i-y
jim jim is offline
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Default Cavity wall insulation

On 16 Nov, 17:46, chudford wrote:
I thought that all modern houses had to have cavity wall insulation.


No: Walls have to meet the thermal resistance standard specified in
the building regs.
There are many ways to achieve that.


snip

We are now planning to have the insulation installed,

I'd be very wary of doing that. It may last a few years but you might
end up with a different problem or 2. Cavity walls need an air gap in
the cavity of at least 25mm against the outside wall. Water vapour
from the atmosphere inevitably percolates through the outside brick
skin & the air gap allows this to run down the inner surface of the
wall. Without it the insulating rockwool or fibre in the cavity will
get wet & become ineffective. Other types of filling have their own
problems. Also shaling may occur on the outside brick face.

but what were
the regs 8 years ago


Much the same as now except required level of thermal resistance has
been upped + some options verboten. You need to check the building
regs for exact info or if you are lucky someone else will be along
this way soon with chapter & verse :-)

and should Redrow have been allowed to get away
with not installing cavity wall insulation?


IMHO they didn't 'get away' with anything: they made the best
engineering decision.


Incidently we thought the house was a bit cold and the heating bills
high.


underrated CH boiler? under-rated rads not heating up fast enough?

You might do better to concentrate your efforts on upping attic
insulation & look at ways of minimising heat loss in exposed sections
of your house - curtains, carpets etc can all help. Can you mask a
wall exposed to the full force of cold winds so that they are
deflected, eg by repositioning a shed? Consider putting rockwool
insulation between ceiling joists over living rooms. We found that
made quite a difference to comfort in our sitting room.

HTH


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