Cavity Wall Insulation

deano72_2

Funny u posted this. Was just thinking today about my cwi.i had it done 18mnts ago & was pleased last winter as it stoped all the condensation on the kitchen walls, anyway i got the brick vents below the suspended floor level & was wondering if they sleeve them before pumping in the white wooly stuff,also i have 1 vent either side in the gable ends which they didnt touch & surely they will blocked so what would be the implecations
How long did it take for u to notice any problems

iamcornholio

Koicarp wrote: »

Brickwork is not waterproof even when new and in perfect condition.

etc

An external wall can become saturated, but will dry quickly and naturally via capillary action and evaporation. Basically the difference in temperatures each side of the wall, and the action of air pressure causes the moisture to be sucked outwards through the wall once the constant source of the moisture is removed. It does not travel inwards

Defects in the wall will allow saturation to occur, or occur quicker and more prevalently than if no defects were present

Vented cavities are an old concept. Apart from the lack of thermal insulation, ventilation is never consistant, so damp air remains and due to this being cooler air, it increases condensation within the cavity - which can actively promote dampness to the internal leaf or cause localised internal condensation by lowering the temperature of parts of the internal leaf

In the OP's case, a few airbricks at the bottom of the wall wont be doing much ventilation to the top of the wall

Koicarp

iamcornholio wrote: »

etc

An external wall can become saturated, but will dry quickly and naturally via capillary action and evaporation. Basically the difference in temperatures each side of the wall, and the action of air pressure causes the moisture to be sucked outwards through the wall once the constant source of the moisture is removed. It does not travel inwards

Defects in the wall will allow saturation to occur, or occur quicker and more prevalently than if no defects were present

Vented cavities are an old concept. Apart from the lack of thermal insulation, ventilation is never consistant, so damp air remains and due to this being cooler air, it increases condensation within the cavity - which can actively promote dampness to the internal leaf or cause localised internal condensation by lowering the temperature of parts of the internal leaf

In the OP's case, a few airbricks at the bottom of the wall wont be doing much ventilation to the top of the wall

In this case the misture is travelling UPWARDS! Via the injected insulation which is below the damp proof course.
Removal of the insulation will mean that moisture cannot travel up the cavity, nor will it be able to travel along joists as they (joist ends) will be protected by the damp course below, and the air moving around them (ends) in the cavity, which was unable to move around previously as the cavity was filled with saturated insulation. This is a classic case of a "new" technology screwing up a perfectly good, but old design.
It is VERY common!

rosie383

Bump!!
We got CWI last year, and although the house does feel warmer, there is a very definite increase in condensation. Every morning I have to wipe down all the windows and window-sills which are very wet, and then open all the windows while everyone else is out.
Should I be concerned about this? It does increase my workload, and if I went away for a couple of weeks I dread to think what it would be like!
In £land the other day, I saw a 2 pack of 'Damp traps' and put them in the 2 worst rooms (porch and kids bedroom). They have made a wee bit of difference. Is there anything else I can be doing instead? It may not be practical to dry off everything each day.

Mrs_A_nonamous

Hi Flint, I hope by now you've sorted out your CWI problems. I'm going through a very similar process to what you reported back in 2011, and was wondering if you could let me know what happened to you next? We had CWI installed in 2010 and the damage it's caused has been huge. My house has turned damp and mouldy in 3 years. We had no problem before the CWI was installed, which we have evidence for in our home buyers survey and independent damp survey done when we bought the house 3 months before . CIGA have been round and seen the damage it's caused, and have told the company to immediately remove the CWI as it was incorrectly installed. I've been told the cavity in our 1929 house is as narrow as 35mm in places. The cavity is retaining water which I believe is partly linked to the dew point and the blown fibre stopping the water from drying out. Anyway, my house is covered in drill holes from putting the CWI in, and from many boroscope inspections, now i believe they are going to take chunks of wall out to remove the stuff. The wallpaper in the hallway is hanging off the wall. There are tide marks visible in the floor joists, looking from the cellar. My daughters bedroom is covered in black mould. I want to take this company to court in order to repair some of the damage they've caused. Does any one know of any precedent where a consumer has won a similar case? Cheers

vegasvisitor

Mrs_A_nonamous wrote: »

Hi Flint, I hope by now you've sorted out your CWI problems. I'm going through a very similar process to what you reported back in 2011, and was wondering if you could let me know what happened to you next? We had CWI installed in 2010 and the damage it's caused has been huge. My house has turned damp and mouldy in 3 years. We had no problem before the CWI was installed, which we have evidence for in our home buyers survey and independent damp survey done when we bought the house 3 months before . CIGA have been round and seen the damage it's caused, and have told the company to immediately remove the CWI as it was incorrectly installed. I've been told the cavity in our 1929 house is as narrow as 35mm in places. The cavity is retaining water which I believe is partly linked to the dew point and the blown fibre stopping the water from drying out. Anyway, my house is covered in drill holes from putting the CWI in, and from many boroscope inspections, now i believe they are going to take chunks of wall out to remove the stuff. The wallpaper in the hallway is hanging off the wall. There are tide marks visible in the floor joists, looking from the cellar. My daughters bedroom is covered in black mould. I want to take this company to court in order to repair some of the damage they've caused. Does any one know of any precedent where a consumer has won a similar case? Cheers

We had it in our last house and would never get it again. It wasn't as bad as yours sounds, but we did have problems with mould on the back of furniture placed against outside walls, which only started AFTER the CWI was installed. The same company came to our door and when I mentioned that I knew the company because we had it done in our last house the guy couldn't get away quick enough...funny that!

I would recommend buying a dehumidifier.

poet123

We are having ours done next week. The OP mentioned 40mm as unsuitable for the procedure is that because it is too small or too big? Any tips from those who know what questions we should ask before we let them go ahead?

Yorkie1

It's too small. The front wall of my house had a gap which was less than 5cm, if I recall correctly, so has not been insulated. The side and rear walls had wider gaps and therefore were insulated.

BobQ

I have had it for 4 years. Concrete floors and cavities about 50mm installed with some kind of polystyrene beads. DPC replaced the old fashioned way by removing bricks, done 10 years ago.

Cannot say I have any condensation problems or any other issues and it has reduced heating costs.

Mrs_A_nonamous

Thanks Lesley74 - yes, we've got a dehumidifier, but we're fighting a losing battle now as water is collecting in the cavity and soaking into the underfloor joists (this was confirmed by CIGA).
I believe, in relation to the recommended width of the cavity, CIGA advice is not less than 50mm - in which case, Poet123, there are other recommended ways of insulating your home which may be more suitable for your particular case.
The point I'm trying to make is that some CWI companies will tell you that your house is suitable when it isn't (like ours) - there are very lucrative government schemes available to businesses to install this stuff. However, getting them to put things right is a different matter. Although CIGA have ordered them to pay for removal of CWI in my home (which is being done this wednesday), they are not admitting liability and will not compensate me for damages (I don't want to make money here, just sort out the terrible mess this has caused)
My advice to anyone going through this is to get it sorted and complain as soon as possible - It has been 3 years since the blown fibre was installed, and yes, we did notice improvements at first with a warmer house. But now the windows are running with water on the inside even if the heating isn't on, the wall ties are in need of replacing, salts are seeping out of the brick work, etc. etc. etc. If anyone has been successful in getting a company to pay for remedial work to put things right, please let me know.