On Tuesday, 18 November 2008 23:56:49 UTC, jim wrote:
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.


Blown in cavity wall fibres are silicon coated to make them water repellent.
As are the cavity wall bats.
https://www.nia-uk.org/consumer/unde...-mineral-wool/