Cavity Wall Insulation - would it help?

lisa701

I'm hoping someone here can offer me some advice.

We live in a 1930's semi which has cavity walls. Each year we have problems with condensation on the windows (upvc double glazed) and the outside walls feel cold. Unfortunately, any cupboards etc. left lying against the outside wall start to go mouldy as condensation forms between the wall and cupboard. Its only a problem in winter, during the rest of the year we have no issues with damp.

Last year was the worst. I think a big part of that was down to the fact we didnt switch the central heating on as we had a wood burner installed in the lounge. Each day I would clear any excess water from the windows and leave any air bricks uncovered etc. but the problem remained. I'm now having to remove my kitchen wall units on that side as they also developed mould on the backs.

I don't want another year of it, but also don't want the bill for switching central heating on just to reduce the problem. I wonder if there is any sort of insulation which may help us (and hopefully keep the house warmer). I've heard people get cavity wall insulation but that itself has got damp and caused major problems and thats worried me.

Thanks

sk240

Hi,

If you are getting problems with condensation on windows then insulation is not the problem, your problem is with not enough ventilation.
Cavity insulation is usually free these days so probably wouldn't hurt, but you would need to make sure the air bricks and other vents were not covered over.
Do you keep all of the doors closed etc, as this would reduce the cross airflow across the house.
Perhaps start leaving windows open a crack, or invest in a dehumidifier.

jimbo_the_jetset

If the problem is really affecting you that badly I would suggest getting a damp surveyor in to assess what the root cause of the problem is.

see here http://property-care.org/index.php?sobi2Search=Search+...+&field_type=all&field_sector=damp_control&SobiCatSelected_0=0&search.x=17&search.y=11&search=Search&option=com_sobi2&sobiCid=0&sobi2Task=search&reset=2&Itemid=382

Do you have positive ventilation in the kitchen and bathrooms? i.e. a fan which is vented outside?

Cavity wall insulation will stop the walls getting so cold and thus water condensing on them. The water vapour will however still be in the air and will go to the next coldest spot, windows or around air bricks. The problem appears to be the amount of water vapour within the house and ventilation

sare_2

It was my experience that having CVI, loft insulation and draughtproofing done made the condensation problem in our house worse. Not an expert in any way, but I assume it reduced the place for the moisture to go?
Wish we'd never done it. I have the same problems you've described every winter.

Yorkie1

The failure to heat the house throughout will have been one of the major causes of the condensation, taken with ventilation as mentioned. This is something to do with colder air being more likely to have moisture in it (or something like that - I know that lack of heating will often lead to mould problems).

Are you keeping lids on pans on the stove? Keeping doors shut when showering and afterwards? Extractor fan in the bathroom? How are you drying clothes? When you remove the water from windows, what are you doing with the wet cloths?

All of these contribute to the amount of humidity which will condense on cold walls.

All respected CWI installers will ensure that your airbricks are replaced with sleeved ones so that the CWI does not block the through flow of air.

I note that sare has had difficulties since doing the listed improvements. Houses are designed to breathe, and blocking up the draughts are as likely to have caused the condensation problems s/he mentions, as the CWI - if not more, because it removes the ventilation. CWI should not remove ventilation at all, simply make the wall less cold and therefore less likely to have condensation on it.

ed110220

sk240 wrote: »

Hi,

If you are getting problems with condensation on windows then insulation is not the problem, your problem is with not enough ventilation.
Cavity insulation is usually free these days so probably wouldn't hurt, but you would need to make sure the air bricks and other vents were not covered over.
Do you keep all of the doors closed etc, as this would reduce the cross airflow across the house.
Perhaps start leaving windows open a crack, or invest in a dehumidifier.

I disagree. The window glass is (or should be) the coldest surface in the room, so if condensation is going to form, it will form there first. It's not unusual to have a moderate amount of condensation on window panes and it's where it does the least harm.

If you get CWI your exterior walls will lose less heat so their inner surface will not be so cold, therefore less likely to suffer condensation.

I've noticed a massive difference in this way between my 1949 house with just rudimentary insulation and the Victorian flat I used to live in with no insulation: the latter suffered horrendous condensation all over the walls while the former just gets a bit on the glass.

Having said that, better ventilation will always help, but you have to balance that against heat loss...

lisa701

Thanks for all the replies.

We did have a damp survey carried out a few years ago but they couldnt find anything wrong. They did suggest that CWI might help but we would need to speak to a specialist company, and at the time funds were tight and no offers available so we didnt get it done.

All the air bricks are left uncovered and we do try and keep a window in each room left slightly open but locked but it doesnt make any difference. We also have an extractor fan in the kitchen and bathroom both of which are used regularly and I often open the window/door wide too when running the shower or boiling a pan to ensure even more air flow.

Think I will contact a few CWI companies and see what they say.

SmeegHeeeed

Same age house, same issues.
We had air vent tiles put in loft-roof to ensure air flow was good in loft.
Used a gut from homesmart to do the cavity walls (free) and extra in loft. I then put an extractor in the spare bathroom (electric one) that worlks with the lights. this year nothing, no condensation so far.

:T:T:T:T