Cavity Wall Insualtion - Good idea or not?

r2015

Be aware that many posters on this Forum complain about condensation after the installation.

I get more condensation on the inside of my double glazed windows in the morning since I had it done.

Possibly because the windows are colder than the walls?

I have noticed that the house takes longer to cool down when the heating goes off at night, I haven't had to have the heating left on all night yet.

Slinky

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Chanes

We bought a house with cavity wall insulation installed by British Gas, we asked for a reduction in the price by 1k in case we found damp caused by the insulation (it is 3k to remove from the quotes we got prior to exchange) It was the only item we negotiated a reduction for on the whole survey, the rest, we considered reasonable wear and tear and fixable for a fair price and we didn't want to lose the house.

We have had no problem relating to damp or condensation, we have had access to the cavity in some place during works and it is dry and so is the insulation. The cavity has a large gap. This is a 4 bed detached built 1991.
I am sure some folks have had issues but this property has had the CWI for 14 years and has been fine throughout. I think if I neglect the brickwork and water gets in to the cavity could may be an issue but who lets their house get so much in disrepair as to become soakable!

Our heating bills are cheaper here than our previous home which was a 3 bed detached and by about £30 a month (G&E)

bmthmark

I've been considering cavity wall insulation as well. I've read a lot of horror stories online regarding this so i'm really not convinced as of yet.
These houses/bungalows were built with a cavity for a reason, to allow air circulation and have a gap between outside wall and internal wall. The questions that keep going through my mind is why would we want to fill this with cheap material's to cause a bridge. Surely we are asking for trouble??
Yes we may save ourselves a few hundred pounds a year in gas bills, but is it really worth the risk of causing damp issues in the property? The clever people that designed the original builds must of had valid reasons to create a cavity.
A friend of mine had it done and he has had nothing but trouble. He is now looking at spending lots of money removing the stuff.
I'm not convinced as of yet that this is a good idea.

Grenage

It's not there for air circulation, it's there to stop water getting from the outside to the inside.

I had it in my 1970's ex council and it was fine. Solid build, cheap to heat, happy days.

New place is a 1905 build, and I don't plan on having cavity wall insulation. No idea why, just go with your gut.

Davesnave

Grenage wrote: »

New place is a 1905 build, and I don't plan on having cavity wall insulation. No idea why.....

There's a pretty good reason; houses built in 1905 won't have a cavity!

System

Cavities are there for a reason, filling them up isn't the best way to insulate a house. It's just a cheap way to do it and has lots of potential problems in our climate

Grenage

Davesnave wrote: »

There's a pretty good reason; houses built in 1905 won't have a cavity!

That's a bit of a generalisation

My house certainly has a cavity; my mate's 1880s house also has a cavity.

Davesnave

Grenage wrote: »

That's a bit of a generalisation

My house certainly has a cavity; my mate's 1880s house also has a cavity.

Yes, but the cavities, where they existed, prior to more general adoption in the 20s/30s, were pretty narrow ones and probably not the best to infill.

People were also still building estates of houses without cavity walls in the 1950s, but they weren't typical of general practice either.

phil24_7

No completely true. Cavity walls were around long before the general consensus of 1920. They were not common place and not necessarily very large either, it varied from builder to builder.

My 1895 house has a small cavity (maybe 50mm) that is filled with rubble/crap. It serves a purpose of allowing moisture to flow down to the slate layer to drain as far as I can tell. My walls are far wider than most though (over 600mm if I remember correctly)