# Cavity wall Insulation. Remove or repair.



## Velochris (25 Jul 2022)

Moved into my semi-detached nearly three years ago. Cavity wall insualtion (blown fibre) was installed in 2006.

Last autumn noticed the plaster had crumbled in the corner of a downstairs room. After the heavy rain we had at the end of February the paint started to bubble on the inside of the west facing bedroom (repointed just after we moved in). 

After some independent investigations they blamed a number of factors, but said the installation was deficient as no sleeves had been put around the air vents (which will eventually cause rot in the floor joists) and signs of rubble in the cavity.

Claimed on the guarantee and the guarantee agency came today. Had heard lots of horror stories about them but found the chap pretty reasonable.

He said they would remove all vents, sleeve and replace with new vents. They would also remove insualtion from the affected walls, and refill. Finally they would put right the damaged plasterwork.

I was pretty surprised as my preferred option was just to have it all removed and me pay an extra for rubble to be removed.

My concerns with the CIGA approach is that they said any loose rubble will be sucked out but anything bigger may remain. Also wonder if removing/refilling just parts of the insulation will be a good idea. I'd have thought it should be all out and then all refilled. 

When I asked if just removal was an option he questioned why, particularly with the price of energy, I would want that. Fair point really as the savings are probably fairly significant given by November I estimate my monthly combines fuel bill will be around £290.00.

I explained I don't want the stress of more damage later on and wonder if the exposed rear is unsuitable. 

In fairness he said he would offer removal only as an option as well. If the problems came back or more developed he said the guarantee is to 2031 so they would come back and remove completely. 

So, anybody had any experiences of this situation?


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## bikingdad90 (25 Jul 2022)

Not had such an issue but our house has retrospective blown in insulation in the main house and then repointed where as the extension has sheet insulation in the cavity. Both have been fine. Mind you we don’t have weep holes as our house is getting on in age.

I don’t see how you’ll get all the rubble out without knocking down a course of bricks or cutting into the wall?


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## presta (25 Jul 2022)

I'm interested that you got CIGA to cough up, their reputation for not honouring the guarantee is the reason I won't have the house insulated.


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## Slick (25 Jul 2022)

Not everyone agrees with me but after years of earning a few Bob from others misery with this stuff my preference would be to remove.

In the interest of openness, I did own a wee flat I rented out and had some issues within the building and managed to convince the local housing association that my block should be renovated. As part of that, the old stuff was removed, but I fought hard to keep the cavity as it should be, but eventually capitulated when informed that the grant would be removed if I didn't agree to more insulation being put in although it was the coated balls glued in position. 

I sold the flat soon after renovation ut I'm still firmly of the belief that there is a cavity for a reason.


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## Velochris (25 Jul 2022)

bikingdad90 said:


> Not had such an issue but our house has retrospective blown in insulation in the main house and then repointed where as the extension has sheet insulation in the cavity. Both have been fine. Mind you we don’t have weep holes as our house is getting on in age.
> 
> I don’t see how you’ll get all the rubble out without knocking down a course of bricks or cutting into the wall?



They take out a brick or two near the rubble and remove. As long as the rubble is not higher than the damp proof course it should be okay (providing the insulation is removed).


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## Velochris (25 Jul 2022)

presta said:


> I'm interested that you got CIGA to cough up, their reputation for not honouring the guarantee is the reason I won't have the house insulated.



I expected the worst as well but, so far, got much more than I expected. Did have some evidence to support things though which has helped.


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## GuyBoden (26 Jul 2022)

Cavity insulation + moisture = Corroded wall ties

Closed cell injected polyurethane foam would be my choice, because it has an inherent water barrier property, but it is extremely difficult to remove and some mortgage companies don't like it.


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## CXRAndy (26 Jul 2022)

Slick said:


> I sold the flat soon after renovation ut I'm still firmly of the belief that there is a cavity for a reason.



Yes an air gap insulation and damp void if the ties are correctly fitted. However if you install or have blown fibre which is non wicking or resists wetting. I've built several properties and extensions with rockwool cavity battens completely filling the 100mm gap. Never seen damp passing into inner wall after 17 years since first works. Our house had blown insulation in one section of the building, again no damp issues. 

Most damp issues arise from coming up through damp membrane at ground level or constant regular wetting from leaking pipes or gutters


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## neil_merseyside (26 Jul 2022)

GuyBoden said:


> Cavity insulation + moisture = Corroded wall ties
> 
> Closed cell injected polyurethane foam would be my choice, because it has an inherent water barrier property, but it is extremely difficult to remove and some mortgage companies don't like it.



I believe the off gassing can make some people quite ill.


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## Slick (26 Jul 2022)

CXRAndy said:


> Yes an air gap insulation and damp void if the ties are correctly fitted. However if you install or have blown fibre which is non wicking or resists wetting. I've built several properties and extensions with rockwool cavity battens completely filling the 100mm gap. Never seen damp passing into inner wall after 17 years since first works. Our house had blown insulation in one section of the building, again no damp issues.
> 
> Most damp issues arise from coming up through damp membrane at ground level or constant regular wetting from leaking pipes or gutters



It may be a geographical thing because of environmental differences or even slight variations across the country with external finishes, but my experience is almost all with wet cast finishes and its completely fine until its not and any crack can lead to ingres.


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## Gillstay (26 Jul 2022)

Have had three houses filled now and all with blown rockwool and its worked well in two, but one had a bit of damp.

I painted the outer wall with a waterproofer as we were near the sea and that stopped it. My experience is leading me to think you just need to match the right insulation to the property. Which can be tricky.


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