I’m sure this was done on the old forum…

Wife is off work & clearly has too much time on her hands:

Is cavity insulation a guaranteed good thing?
Is glass wool a good material?

140sqm for £199 with a govt grant ???

we’ve had them knocking on the door in the last week offering the same deal. when we said no he offered to do it for a £100 cash!!

DO IT.

Well worth it, easily pay back, definitely a more comfortable house – the days of dodgy installs and damp problems are gone.

And while you are at it, nip down to B&Q and buy a shed load of their power company subsidised loft insulation and slap it in up to a depth of 300mm+

matt_oab – you do this sort of thing for a living, don’t you ?

is glass wool a good choice then ? (though not sure if any alternatives are on offer) – I thought it was mostly polystyrene beads

I am not a major expert on cavity wall stuff – we work with solid walls 99% of the time.
Either work as well, with the glass wool I *think* you are marginally sidestepping some *possible* damp issues compared to poly beads that insulate slightly better for a given depth/flow in difficult walls more easily so need fewer holes drilled.

cheers

OP- do it if the job is done well.

[slight hijack] Matt- do you know of any links to resources to learn more about improving the u-value of solid stone walls without losing thermal mass or changing exterior? Seems nigh on impossible to do anything worthwhile without simply adding to massive construction (and thus significant space loss). [end hijack]

crouch potato:
http://www.natural-building.co.uk/pavadentro_renovation.htm
http://www.natural-building.co.uk/pavadentro_renovation.htm
http://www.greenbuildingforum.co.uk/newforum/ (and search)

As you say, difficult to do. External insulation is ALWAYS cheaper, easier and less fraught with damp issues.
Internal insulation works well, but as you say you loose room size. In addition the moisture issues are many, complex and detailed. But it can be done, you just need to know what you are doing. See the technical manual for Pavadentro.
You also tend to trade off thickness of insualtion – ‘thick’ but nice natural, breathable material VS ‘narrow’, but non breathable and petrochemical.
Green Building forum guys are very helpful.

Cheers Matt- moisture either internally or in the structure was one of my main concerns, I’ll take a look at your links.