Jim wrote:

"John Stumbles" wrote
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?

It's applicable to walls constructed of two skins of masonry (bricks or
blocks) with an air gap between them. When retrofitted, holes are drilled
in one skin (usually the outer) and fibrous or granular insulating
material
blown into the gap. In USAnia I think you generally have timber-frame and
other constructions where this wouldn't work.

Thank you; I have seen parallel brick walls with a space between, tied
together with an extra long brick every so often, in buildings hundreds of
years old. I don't know anyone in the US who lives in a home like that....

Here we used zinc ? plated steel ties to hold the 2 layers together. Your method
of cunstruction is certainly cheaper but I'd like to see comparative thermal
performance figures.

Graham