Cavity wall insulation causing damp/ mould problems?

yellowcrocus

Does anyone have any experience of this?

In 2007 we bought and renovated a 1930's semi, which had no damp problems except a small patch inside a walk in cupboard on an outside wall. After applying new plaster to everywhere we have had no further issues with damp until we got free cavity wall insulation along with everyone else on my street in Autumn 2010. While filling the cavity walls the company used silicone to block up most of the airbricks I can see on the outside of the house. Since then the council sponsored insulation company have changed hands.

Ever since, we have had terrible condensation on the windows in the mornings and on the bottom of the walls, and have had black mould growing on the windows and in patches on the plaster around the house. We had the new insulation people round who, after repeatedly denying any fault, eventually admitted off the record that the previous company had done a terrible job. They left many holes in the insulation, which was causing condensation to collect on the cold spots. They refilled the cavity, cleaned off the mould spots, and gave us £100 compensation.

After the refilling of the cavity, the problem has got worse. The mould is growing very quickly now and has stained the paintwork in several spots around the house. The silicone around all the windows is stained black. There are actual puddles collecting under the windows overnight, when I wipe over my window frames in the morning, the cloth is dripping wet. Far from saving me any money, I am actually wasting more energy as I have to keep the windows open to allow the compensation to escape. I am extremely worried about this as I need to sell my house this year and obviously any sign of damp/ mould is a huge no no to buyers. In addition to this, I have an asthmatic child and a young baby and I am concerned about their health.

Does anyone have any experience with cavity wall insulation who could advise me on the likelihood of the liability of the insulation company or on any remedies for my problem?

Thanks.

art_for_arts_sake

If your airbricks are still blocked then your house isn't getting the ventilation it needs. Did the company remove the silicon sealant when they came back or is it still there? It used to be common, even though incorrect, practice for some insulation companies to block airbricks. Also, some products used for insulation only needs to become slightly damp to cause internal damp problems. http://www.askjeff.co.uk/cavity.html

yellowcrocus

Thanks for your reply, I forgot I had written this (it's my age! )

The airbricks are still siliconed up, as the weather gets colder both the condensation and the mould are getting worse and worse. I am going to contact the city council (who commisioned the insulation company) and express my concerns about my children's health. Hopefully I can get them to remove the silicone and install some air vents.

UncleZen

There would be no point in unblocking the air bricks, the air has nowhere to go because the cavity is full of insulation. When the cavity is full of insulation there is no ventilation to be had (except on new builds where the insulation is fixed to the inner wall and a gap is left to the outer wall for 1) ventilation and 2) keeps the wet outer wall away from the insulation).
Ask yourself this. If the design of the house is such that ventilation is required in the cavity, do you think filling the cavity a good idea?

tony6403

Cavity walls are not vented.
Airbricks are for
- underfloor ventilation ; these should go right through the structure so that their effectiveness is not reduced by allowing the air flow to escape into the cavity.
- combustion air for fuel burning appliances (airbricks sealed from the cavity)
- on older properties larders and bathrooms/bedrooms might have vents but again not into the cavity.
Improvements can be made by not drying clothes on radiators , using an extractor fan in kitchen and bathroom , reasonable ventilation .
But, even your breath can cause your bedroom windows to stream with condensation.
We found that a dehumidifier eliminated the problems that we had.

ian103

we are currently using 2 dehumidifiers in our house, 1 in the lounge and one in the hall, the house feels lots better for them, not sure how much they cost us to run as combined theyre notionally 400w but they only run occasionally through the day / night. we put the one in our lounge after finding a patch of condensation on the wall - I suspect the issue is probably poor workmanship when build and when cavity filled. We extract about 1 litre of water a day from both machines. And yes the house feels warmer and drier. In the fullness of time I intend to fit a Nuaire positive vent system but as we already had the 2 dehumidifiers thats what we are using

thebaldwindowfitter

can you tell us how often you have your heating on in the house and what type of heating it is is the condensation mainly in bedrooms do you dry clothes in these rooms

UncleZen

tony6403 wrote: »

Cavity walls are not vented..

Ours most definately are, we have solid floors and the air bricks are above the dpc.

spratster

i had problems with damp and mould growth after cavity wall and loft insulation , tried bleeching and redecorating etc and it kept comeing back ?
a friend told me about a local firm in the leeds area called cavaid !
they came out , surveyed my house and recomended venting the soffits ?
got the job done and now so far ,fingers crossed, i dont get the damp/mould and minimal condensation !
oh and they vented my loft hatch aswell lol apparently to allow
air to circulate again ??
works for me , and cost me less than £200 probably saved that on paint and bleech

new_owner

spratster wrote: »

got the job done and now so far ,fingers crossed, i dont get the damp/mould and minimal condensation !
oh and they vented my loft hatch aswell lol apparently to allow
air to circulate again ??
works for me , and cost me less than £200 probably saved that on paint and bleech

I hate to think of the heat £ loss now your venting through your loft hatch. Sounds like you property was not suitable or correctly vented.

Yorkie1

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