Jim wrote:
"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?

Fibres blown into the walls under aor pressure mostly IIRC.

It's a fairly simple way of adding insulation to a double skinned
masonry wall.

Thanks,
Jim