I know that this has been covered several times but there never seems to have been a definitive conclusion. Are there any comparisons between the two systems in terms of suitability for an average detached house?
I am going to get cavity wall insulation installed but am left wondering what the advantages (apart from a slightly better U value) to using the polystyrene beads.
Andrew
AFAIK Poly beads eventually shrink.
Can't see the OP, but I used to install CWI for many years and the main disadvantage is that poly beads escape from every tiny hole, often leaving huge voids. They are supposed to be coated with a type of adhesive as they are blown into the cavity but this seldom works as it should and installers often switch this feature off because of blokages during installation. Blown glass fibre never really blows out of holes because it tends to 'set' into a blanket within the cavity
I have had poly beads for more than 25 years now. They only leak if you drill a hole through the wall and then only a few. Mine are stuck together, but only a bit.
Dear Andrew My advice is not to worry too much about minor differences in U value but to absolutely insist on a process (whatever it is) that is fully reversible and the insulation is fully removable but machine sucking it out. This WAS the case with Rentokil rockwool in the mid seventies but suspect things have changed a lot since!
chris
Thats one noticeable advantage with poly beads in situations where there is a slight risk of problems occurring, ie non-recommended cavity wall types.
NT
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