Cavity Wall Insulation

FLINT

Hi all I just wanted to share my views with the forum regarding cavity wall insulation. I had this done in 2004 after receiving a partial grant from one of the energy suppliers.

Boy oh boy do I regret having it done. The type that was injected was a white mineral fibre wool type. As I have gotten older and been doing various house redecoration and renovations I have become more and more aware of damp issues along the walls that is filled with the insulation. My house is semi-detatched.

I have had allsorts of issues such as a rotten floor joist, discovered whist renewing our kitchen, rotting floorboards at the foot of my hallway, damp and peeling paper along my staircase.

Whilst having a new physical damp course installed the brickies drew my attention to the fact that the material was wet through.

I have a suspended wooden floor and looked under not too long ago to discover wet rot on a couple of the joists, I asked a builder to have a look and he noticed that the underfloor vents had been blocked by the installers so not allowing free airflow under my floor. Since then I have also had extra vents fitted, this has helped but not much so i contacted CIGA who are the body who maintain the 25 year guarantee.

Today I had a surveyor out from the company who bought out the original installers, I showed him my problems and to my surprise ADMITTED that my cavities at 40mm were not really suitable for the fill and so it should have never been done.

I am due to have the stuff removed next week all being well and then the fight begins for compensation for redecoration and repairs.

If anyone is interested or is experiencing similar problems I will update the thread.

vegasvisitor

We had it in our last house, and never experienced problems to the extent you are - fortunately. However, we did find that if we put things against the outside walls (bookcases etc) sometimes the back would go mouldy, just slightly. We just kept things right off the walls after we noticed, but pretty horrible. Makes you wonder if it's a good idea in general.

Recently a guy came to our door offering the job to be done with grant etc, when I mentioned the previous issues he started saying it would be a different supplier and materials etc, but then I asked the name of his company and when I said I recognised it he couldn't get away quick enough!! :rotfl:

iamcornholio

So your problems have nothing to do with cavity wall insulation per-se, but due to incorrect installation

FLINT

iamcornholio............In answer to your reply, yes there was a problem with the installation as for one my cavity width isn't suitable which wasn't picked up prior to installation and secondly not enough stuff was pumped in. With regards to the material itself I told the surveyor that in places it was wet he said this wasn't possible as it should be treated with silicone however when I showed him that it WAS wet he then agreed that it should come out.

Please don't get me wrong I'm not trying to put people off getting this done as I'm sure if done correctly the benefits are good, however for me my problems will continue even after removal.

27col

I would be interested to know how they remove cavity wall insulation. Perhaps the op will tell us how they did it, when it's been done.

FLINT

Hi there 27col, from what the surveyor told me they will re-drill the holes were the insulation was blown into, here they will pump compressed air, to force the insulation down o the bottom were bricks will be removed to empty the material. He also said that they will install additional air bricks to aid drying the brickwork.

Just out of interest are you having problems yourself with cwi?

iamcornholio

If you have persistent damp insulation, then there is a problem with the external brickwork/pointing, or another problem at eaves level which is allowing moisture into the cavity. Cavities, with insulation or not do not remain damp

There is absolutely no reason why you need airbricks in the wall "to aid drying the brickwork" when this stuff is removed. The cavity will dry naturally (unless you have a problem as above), and in fact venting the cavity will remove the thermal insulation provided by the air gap and have a negative impact

That company is giving you bad advice if they want to install airbricks to vent a cavity wall

27col

Hi there FLINT. No, I have never had the slightest trouble with my CWI. I was just curious as to how it might be done. I am nosey about anything to do with buildings.

izzieprest

oh bum we had this done yesterday to our new house lol

i hope to god it was done properly. heres me all excited ill save on energy bills:(

patty65

I've just had a surveyer to survey my house for free cavity wall insulation through my gas and electricity supplier.

I can't get it done because of the sloped roof garage attached to the side of my house.

It will need either scaffolding or a cherry picker to get it done and my gas and electricity supplier will not pay for it.

So no cavity wall insulation for me.

Koicarp

iamcornholio wrote: »

If you have persistent damp insulation, then there is a problem with the external brickwork/pointing, or another problem at eaves level which is allowing moisture into the cavity. Cavities, with insulation or not do not remain damp

There is absolutely no reason why you need airbricks in the wall "to aid drying the brickwork" when this stuff is removed. The cavity will dry naturally (unless you have a problem as above), and in fact venting the cavity will remove the thermal insulation provided by the air gap and have a negative impact

That company is giving you bad advice if they want to install airbricks to vent a cavity wall

Brickwork is not waterproof even when new and in perfect condition. Cavities with INJECTED insulation DO retain water, as the insulation breaches the damproof course, enabling moisture to rise via capillary attraction. In new build the insulation starts on the damp proof course rather than below it, which means this isn't a problem.
Vented cavities have been around since cavities got trendy in the 1930's and work well, in doing what they were intended to do- keep the inner skin dry. Yes the thermal insulation performance is reduced (when compared to closed cavities), but they are still better than solid walls, and depending on the age of his building it may be that the cavity was intended to be vented.
Injected cavity wall insulation frequently causes the problems outlined by the OP.