Hi, could anyone please advise me? I'm renovating a 1960s bungalow and want to insulate the cavity walls, which are brick and block and open at the top. My builder suggests we simply pour polystyrene beads into the cavity via the open top. He has seen this done elsewhere. Is this advisable? Looking through the web sites of some installers, and a couple of other sites ('simplify DIY' and 'homeenergysaver'), it seems the beads are normally injected under pressure and mixed with an adhesive at injection.

I expect it would be a lot cheaper just to pour them in loose and we think it would prevent rats using the cavity because loose beads would block their runs. Are there any disadvantages, though (e.g. less effective as an insulator, may leak out of any holes, may settle, may not fill all crevices)? My builder was also called to repair a damp wall. When he opened the cavity, it was filled with rockwool but ants had carried soil up into the rockwool and built a nest that bridged the cavity so water passed across. He believes loose beads would also prevent that. Grateful, for any advice. Best regards, Ian

Proper professional job is best -- the glue is important also the beads will settle if you loose fill leaving voids. Usually I say DIY but not on this one.

Thank you all for your helpful comments. CWatters, I had read the other discussion, thanks - it seems to suggest that Ecobeads are best. However, does the problem of reaction between PVC and Polysterene also apply to the professionally injected polystyrene beeads, with adhesive? Many thanks, Ian.

Oops stuck this on the foam thread as i was reading at the same time...

Definetely don't do pour your own beads...

a) it won't have a 25 year CIGA guarantee (which can be a godsend if your walls were crap anyway!)
b) it will mean more labour for you
c) it will cost more than the discounted grant price - especially if you include your labour costs. You should be able to get them for less than £200 - the bigger the house the bigger the CO2 saving and hence CERT grant - so cost to the customer is usually constant.
d) You're not guaranteed to fill all the cavities yourself.

Go to this page http://www.bbacerts.co.uk/query3.html

And take a look at the drill patterns and on the left hand side click walls/cladding, then blown in cavity wall insulation. Click the swirly arrow to download the certificates.

e.g. to save you time these are the first 3 examples...

http://www.bbacerts.co.uk/certs/17/1720i2_web.pdf (page 7)
http://www.bbacerts.co.uk/certs/32/3228i3_web.pdf (page 7)
http://www.bbacerts.co.uk/certs/37/3706i2_web.pdf (page 7)

You'll notive the drill pattern always includes areas under the windows, and some extra at ground floor level, with a larger amount at the eaves to make sure it get topped up properly. If you drop them in at the top, you'll get holes under windows, under wall ties, and at the corners of the building

PS. I'm not a cavity salesman or installer - but did my reasearch when I wanted mine doing. I do know someone in the trade. She also told me her worst day - was when a potential customer said "what? £150!!?? - I could get a flight to Spain for that!" Doh!.

Simon

Vacuum it all out yourself then get a grant!

Any vacuum with a large drum/container to collect in or even a garden vac.

My house was built in 1989 and allegedly had insulation put into the cavity walls when they were being built. Recently, I had a shower put into the bathroom which required a hole in the inner, thermal block wall to make space for the shower unit. Imagine my surprise when this revealed that (in this area at least) there is no insulation material in the cavity wall.
Two Questions :
1. How can I find out if there are other areas missing this foam board? (or whatever it is that they are supposed to have put into the cavity)
2. If there is piecemeal presence of this insulation, can I have wall insulation put in, and, if so, what's the best product for this situation? (rockwool, polystyrene beads, foam)?
Thanks