cavity fill insulation

ExArmy · Sep 27, 2012

what is the history of this? all i can find on the internet is (i suspect) a load of rubbish from the companies that install it that are just trying to get you to buy it. on one forum i saw 2 posts from different users with 1 post that had the exact same text which started "Having been a cavity wall surveyor for some years let me put your mind at ease."

Read more: Can cavity wall insulation cause damp in the house? - DIYnot.com - DIY and Home Improvement

I had a guy round today trying to give me some (free to everybody now), i questioned him about it causing damp problems and he said that was the old stuff (rockwool) but now they use some new stuff (glass fibre) and it does not soak up water, so it will not cause damp problems.
I've worked alongside builders a fair bit, alot have mentioned jobs where they have had to remove cavity insulation as it was causing damp. my house is about to get re-rendered, hence why i'm thinking about getting it done then i would not have any holes on the house. and also it seems the main problem is cavity insulation exacerbates a damp problem, but if a house is well maintained (PVC gutters in good nick, damp course intact, roof sound and just about to be rendered) then it shouldn't be a problem

also another thing this guy mentioned, I told him he needn't bother insulating the porch as it has 50mm sheets of insulation in there already as i only built it last year, and he said "yeah but theres still a cavity, we can fill that up too" and apparently they think that any sort of cavity causes a house to get cold, and the answer to this is pumping them full of insulation. so that last part put me off a bit, it seems they have no idea of what a cavity is for and are basing their sales pitch on a load of factually incorrect information.

Rampage · Sep 30, 2012

Interesting, we have cavity wall insulation (white powder stuff) and get damp problems all around the house. We have started finding mouldy clothes in the wardrobes too.
My parents had a much worse problem and they had some sort of an fitted into hallway that transfers air between the loft (it's a bungalow) an the hall. Something to do with positiv pressure or something?! It's working though apparently.

ashrow · Sep 30, 2012

To sort the damp issue, i had to install trickle vents to the windows and i fitted 4 roof vent also (house needed some air circulation)
Been ok now for the last year

Roof vents around £40 each, trickle vents around £4 each and i took a total of 4 hours

Hope this helps

snowhead · Sep 30, 2012

Injected Cavity foam got a bad name in the early 70's.
Everyone and his dog's mate's mate were jumping on the bandwagon buying the gear and having a go.

I had the first house I bought done in the early 70's with foam.
It was all about the consitency of the foam and how to get full coverage in the cavity that people didn't understand.

The house I'm in now I bought 25 years ago and this one was foam filled at new, it's been no problem.

They seem to use Rockwool or similar nowadays, but whatever is used it's down to the time spent surveying and installing as to whether you get problems.

You can end up with mould inside caused by poor ventilation even in houses built with cavity batts attached to the inner leaf at the time of build.

ExArmy · Sep 30, 2012

after researching the matter more, i think i'm not going to bother. it's a mid terrace with a combi boiler so heating is not exactly a fortune, and i'd rather pay a little bit more on my heating that risk having to spend thousands fixing a damp problem. at the end of the day, the cavity is there for a reason.