Weatherlawyer wrote:
Phil L wrote:
wrote:

With all this talk of insulation, is it workable to cavity insulate
stone walls with random cavity? I would have thought so, though
expect a lot of filing holes would be needed. But I know its
advised not to cavity insulate some wall types.

definately not.

A housing estate was insulated in Scotland (new build) and was later
found to have undressed stone on the cavity side....after six months
or so all the houses got damp, and I mean seriously damp, fungus
growing outof walls, timbers rotting everywhere, the rsidents had to
move out while the houses were ripped apart and the insulation
removed.

The *minimum* cavity size to be filled must be at least 50mm, with
undressed stone this is impossible to gauge, some places it might be
75mm and others only 35mm...it just doesn't fill and water ingress
is the result.

So what you are saying is that all cavity fills are likely to cause
problems but that with a wide enough span, most homes get away with
it?


Most homes have a cavity of 50mm or more, CWI isn't garuanteed under this
thickness so no (registered) installer would do it, and certainly not
undressed stone....it's possible to get it done as a foreigner, cash only,
no garuantee etc, and then twelve months later pay about 5K to have it all
removed.

Whilst it explains the uselessness of modern cill board sizes, it
doesn't alleviate fears of TB resurgence. I get the impression some of
us are living in time bombs.

Is it really so?


No.
Almost all CWI installers have insurance backed 25 year garuantees issued by
CIGA
http://www.ciga.co.uk/
Who are independant of the CWI industry, meaning that even work completed by
companies who have long since gone out of buisness is still covered.

Any jobs done during the 'cowboy' period during the late seventies will
either have been repaired or demolished before now, and it's a requirement
during house purchases to provide the garuantee, so it's unlikely many
houses are 'timebombs', given that problems will show themselves within
weeks or months of CWI installation.

Check your brickwork with an hose pipe. If some of the bricks are
upside down it will show. Most face bricks are designed to shed water.
I doubt it is crucial but in a frost....

(Just thought I'd frighten you while we are telling horror stories.
And now children: Good night!)

I've made a small jpeg to show what I mean:

http://i1.tinypic.com/rvybgy.jpg