Urgent Cavity wall insulation advice needed..

[ellal]

Got our cavity wall insulation done a week or so ago.

However, despite the quote being for mineral the fill was done with beads which I didn't know about until the end of the job. I said about the original surveyer mentioning that although there were some damp issues with fibres it was 'solid' and future work would not mean the insulation coming out. However I was told by the installers that a resin/glue was pumped in and the beads would bond thus it was the best option of the two.

Not knowing much about this I accepted the explanantion, but a few days later when the wind got up it started 'snowing' in the kitchen through an air vent. A quick check under the floor boards found large piles of beads where the air bricks are (despite them being 'brushed').

Just had them back, and they have said there is a problem with the bonding, and have said they may re-blow it.

So any advice on the following would be grateful:

Do the beads actually stick together using this method, or was I being told a porky?
If they have to reblow should I insist on fibre, or does the damp problem become more of an issue if it is indeed the case?
There was mention of now changing the airbricks and sleeving, so should that have been done in the first place, or was 'brushing' sufficient?

cheers

[blondini]

This is just my personal opinion and experience as I once had beads and I would not have them again as there was no discernible benefit after instalation.

The insulation value of the beads may look ok on paper but I reckon that in the real world the voids between them must allow significant air movement. Heat can therefore just convect upwards and outwards through the cavity, and cold draughts can pass the other way.

Never mind the bonding, they are supposed to be bonded, but if you were quoted for mineral fibre you should have been given mineral fibre. I would insist on fibre, it is treated to prevent damp from passing.

Is your property in an exposed area?

[ellal]

Not too exposed, but the two north facing rooms (those having 3 outside walls) were appreciably colder than the rest of the house.

I must admit that there did seem a noticeable difference after the insulation was put in.