Jim wrote:

"Eeyore" wrote
Mary Fisher wrote:

In January 1993 we paid something over £300 for cavity wall insulation,
accompanied by the mocking of neighbours (just as they did in January
2005
when installed solar water heating). They said it wouldn't make any
difference to anyone except the company which did it.

SWI was quite rare in those days and we weren't eligible for a grant. We
felt the difference in comfort immediately, we didn't measure any money
saving but that wasn't the purpose.

I don't have much in the way of cavities to fill since my house is mostly
of solid 9 inch brick wall
construction.

I did however notice the diference after it was painted with 'masonry
paint'.

Yes, that works wonders. We painted our home with a pale greenish-blue
paint originally designed for use in concrete swimming pools to seal the
pool. It lasts forever too!

Maybe not forever. 10 years on it's wearing quite well aside from a couple of
patches where the material condition underneath was marginal.

It is very effective though. A similar improvement may be achieved on buildings
with bare brick exteriors by applying a silicone based spray which rejects water
penetration yet still allows the masonry to 'breathe'.

Graham