"george" wrote in message
...
David J wrote:
On Sat, 07 Nov 2009 16:23:28 GMT, "Phil L"
wrote:

David J wrote:
Not quite diy, but does anyone have a view (positive or negative) on
modern cavity wall insulation with foam or granules.

I had a previous house done with insulation foam in the 1970s and I
had no problems at all - apart from giving myself a problem later when
trying to drop a TV cable between floors via the cavity. The foam
insulation reduced my annual heating bill by 25%, and soon paid for
itself.

At the time I remember a brief cancer scare in the newspapers about
homes treated with this foam - but that ultimately came to nothing.

I had assumed that my current house, built in 1997, would have had the
wall cavities filled with insulation slabs at the time of building -
but some recent drilling through the exterior walls confirms that I
was wrong about that. Maybe the current building regulations for
insulation were not in place in 1997.

David
houses are still being built today without CWI - it's not required if
the u value of the walls can be achieved without it, that is to say,
thermal blocks can be used, coupled with internal drylining can be as
efficient as cavity insulation.

I'd get it insulated if it were mine - I used to install CWI for many
years and I can tell you that they use fibreglass now, and very
occasionally, polystyrene beads, but these have many drawbacks, not
least when the house comes to be demolished as they never disintegrate
and also knocking holes through creates huge voids higher up the wall,
fibreglass tends to 'stick' better on the rough surfaces of both brick
and block.

There's grants available via energy suppliers and also it can be
installed for free if you or your spouse recieves any benefits


Thanks for that info Phil. It probably explains a lot, since my house
exterior wall construction is as you stated: standard facing brick + air
cavity + 100mm thermal block + drywall
plasterboard. I have not seen the mu value for this construction, but
I presume it can only be improved the CWI.

I checked the 'free' CWI deals available, and it looks as if it
restricted to buildings constructed between 1924 and 1982. I'll check
further.

David
i bought a thermometer gun from maplins,
you point it at a wall
and it tells you the temperature.
useful for showing where insulation is worth doing,
in my case the top few feet of the walls seems to leak heat through the
edge of the roof.

The most common point of cold bridging - where walls meet each other, roofs
and the ground.