Cavity wall insulation

thescouselander

We've recently had someone trying to sell us cavity wall insulation and in principle we would like to make the house a bit more energy efficient. The problem is I've heard about potential problems with damp and also damage to wall ties as a result of moisture being trapped in the cavity. Has anyone here had experience of cavity wall insulation and how did it turn out?

WestonDave

We've got it - having read much of the same as you've read, we made sure we went for the bonded beads (polystyrene balls in plain english!) rather than the more common rock wool. The downside to ours is that if you ever drill into the wall you are inclined to get some come out but it doesn't absorb water (it allows it to drain down through the gaps) and it doesn't slump as rockwool can (which can lead to cold spots). We've not had any obvious damp problems from it - not aware of any wall tie issues either. To be fair wall ties can fail anyway as many of the earlier ones were plain rather than stainless steel.

In terms of the experience the house is warmer in winter and cooler in summer than without it.

thescouselander

Thanks! Anyone else?

maas

The house ive just bought had cavity wall insulation installed by previous owners (the poly ball type). According to independent damp specialist it is one of the causes of the damp in the house, as the insulation is carrying the damp from the outer leaf of the cavity wall across to the inner leaf.

I've just had a DPC done, dp membrane added and all the walls re-plastered, so hopefully all fixed.

Some people say they never had problems with damp until they had cavity wall insulation done and then had problems (do a search on forum here), others say they have no problems whatsoever.

Personally if I didnt already have cavity wall insulation I wouldnt get it.

tracey3596

AahH .... okay, ours was done - oh, 10 years or so ago?
So I've no idea what type ....
Anyway, ever since then we've had TERRIBLE condensation every winter, top corners of walls and windows especially - even with a dehumidifier and window trickle vents. :mad:
Mind you, there COULD be a variety of causal factors which I won't go into here.
As MAAS hints at, I have researched and found evidence (online; you too can spend countless hours researching if you feel the urge) that "bridging" a cavity with ANY supposed insulator can lead to problems with "migration"; trapping moisture; settlement and cold-spots; etc etc.

Personally and knowing what I now know, I would not have cavity wall insulation fitted without some guarantee that condensation or other problems would NOT result from said insulation. :cool:

I would rather spend more and use exterior insulated cladding.:p
Oh, if only

phead

There is no evidence that cavity wall insulation causes damp or condensation, in fact quite the opposite. Studies show it reduces both.

There have been millions of installs with any serious problems, multiple government bodies recommend it and anyway it's backed by an independent 25 year guarantee.

System

phead wrote: »

There is no evidence that cavity wall insulation causes damp or condensation, in fact quite the opposite. Studies show it reduces both.

There have been millions of installs with any serious problems, multiple government bodies recommend it and anyway it's backed by an independent 25 year guarantee.

think you should maybe do some more reading...

Furts

On a positive note my poly bead cavity insulation has reduced heat losses, made the house cooler in summer - just a little bit - and there has been no condensation problems.

I cleaned and repaired my cavities, rectified rising damp and repaired and re-pointed my walls prior to installation. Most people do not not go down this route.

On a negative note the sales people and installers operate in anti consumer manner. The work is not supervised, or checked and after sales support is woeful.

My installation was by Domestic and General. I would not recommend this company to anybody.

jmhgibson123

i would like to ask, i had cavity wall 2 yrs ago, and since then i have noticed that my outside wall is soaked and does not seem to dry out, its almost all of the wall just small sections near the very egdes that seem drier?? is this caused by having the cavity wall stuff i think they type i had put in was the wool stuff not poly ...and advice??

Furts

jmhgibson123 wrote: »

i would like to ask, i had cavity wall 2 yrs ago, and since then i have noticed that my outside wall is soaked and does not seem to dry out, its almost all of the wall just small sections near the very egdes that seem drier?? is this caused by having the cavity wall stuff i think they type i had put in was the wool stuff not poly ...and advice??

It might be a problem.

Your observation suggests the edges are dry - this is plausible if the wind, or draughts within the cavity, or the remaining insulation is drying out these areas. Also any roof or verge overhang will help the adjoining "edge" areas remain dry

To counter this argument your inside wall would be expected to be damp. But, if you have solid brick walls you may not observe this, or if your walls have vinyl silk paint or if you have dry lined walls.

If you go in your roof space are the walls wet?

A lot of walls appear wet at present - mine do- but this is because of the excessive rain we are experiencing. Are these walls the ones facing the prevailing wind and rain?

In addition, prior to the cavity wall insulation being installed these walls were drying from the inside outwards. Now they cannot do that as effectively- the insulation hinders this.

My apologies if this is not the quick answer you were hoping for. In essence, you need to investigate to establish more information .

Hope this helps.

jmhgibson123

i will get someone to check the loft for me but yeah i have wallpaper on that wall and its peeling off so im presuming this is soaking through. it is a wall thats fairly exposed to wind and rain, it just seemed strange to have most of the wall saturated and a few small areas look dry, will attempt to get the loft checked and report back thanks for the advice x