"Jim" wrote in message
t...

"Mary Fisher" wrote
In January 1993 we paid something over £300 for cavity wall insulation,

I am not familiar with this term. In the US, I have always used
paper-faced rolls of fiberglass stapeled between the wall studs. What is
CWI? The same? Sprayed foam/cellulose?
Thanks,
Jim


Houses built until fairly recently in Britain have only had an air gap
between the inner and outer walls of a house. That helped with insulation
and preventing damp. It was better than earlier buildings which were single
walled.

Newly built houses have built-in blocks (usually) of insulation between the
inner and outer walls.

Those of us with empty gaps can have them filled at our own cost or,
nowadays for many people, free. Because of not being able to access the gap
solid slabs can't be inserted so loose filling is blown into the gap.

In our case (and I think it's the most usual) holes are drilled in the
mortar between bricks at certain distances from each other, a pipe is
inserted and shredded mineral fibre is blown into the gap from outside. It's
a quick, if noisy, business, a lorry stands in the street with a large bore
hose leading to the house, the pump is in the back of the lorry and can be
heard from several houses away - that's how we know when someone's having it
done :-)

Afterwards the holes are re-filled with mortar and the workmen leave. As I
said, it's very quick and if you haven't had any wall insulation before you
can feel the difference immediately - far sooner than you can with roof
insulation although the fuel savings aren't as obvious.

I'm talking about brick-built houses of course, houses built from other
materials will probably have different means of providing insulation if it
wasn't built in from the start. I say that to avoid being flamed :-)

Mary