Fred wrote:
Hi,

Someone knocked on the door offering cavity wall insulation for £140.

I'm not sure whether the house (built mid-70s) has cavity wall
insulation or not; how can I tell?

If I do need it, is £140 a good price and are some companies better to
use than others?

I understand they inject something into the cavity but what do they
use? Is it like that awful expanding foam that you can't clean off?
What stops it rising up the wall and coming out of the top or through
air bricks etc?

We have a meter box cut in the side of the wall. Is there a danger
that the meter box will be flooded with foam?

Also the builders for some unknown reason decided to put the soil pipe
and rising main in the cavity behind the bathroom wall. I don't know
if I am worrying unnecessarily but if we ever needed to access the
soil pipe or main, would it be possible if they were caked in foam?

Thanks in advance.

They don't use foam anymore, it's dry fibreglass, treated with silicone to
prevent water tracking across.
The fibreglass is pelletised (into small balls) and blown in with compressed
air...sometimes rockwool is used but the method is almost identical.
It only rises up about 12 inches, but will fall down (via gravity) about 4
feet, and across about 2, once installed, it never moves again until you
remove it manually