Damp (since cavity wall insulation)

jacobsdaduk

Hi,

A few years ago I had my home - built in the 1980's - cavity wall and loft insulated by The Mark Group.

Since then, I've noticed an increase in surface damp on the corners of some walls. It's made worse when cooking and although I try to keep the windows open when I cook it doesn't get any better.

I came across some advice on this website but none of it seems to help.

My question is: are we making the problem worse by keeping the heating low and switching it off at night? The reason I ask is that we don't like the house too warm and I'm wondering is this is making the damp problem worse i.e. stopping it from drying out.

Any advice would be appreciated.

Doozergirl

Sounds like you might have a ventilation and air circulation issue if it's moisture from cooking and appearing in corners. It is likley to be condensation, not 'damp'.

It could be clinging to cold spots - perhaps the wall insulation isn't reaching the corners.

You need good extraction, perhaps working automaticaly with high humidity levels rather than relying on being switched on when you're using the cooker, bathroom etc. Also check you have trickle vents on your windows and they're open.

Keeping rooms warm will keep moisture more in the air than condensing on the wall. Whether you do that is your choice.

Furts

jacobsdaduk wrote: »

Hi,

I came across some advice on this website but none of it seems to help.

My question is: are we making the problem worse by keeping the heating low and switching it off at night?

The website refers to increasing the heating to cure problems such as yours. This is good advice.

You have chosen to go contrary to this by switching off your heating at night, which is the time when problems occur. Hence the answer to your question is yes.

teneighty

And probably worth getting a good extractor fan in the kitchen, preferably extracting cooker hood (not recirculating). Far better than opening windows which just cools the house down and makes the condensation worse in my opinion.

tony6403

Given that you don't like the house too warm, a good quality dehumidifier will take out the moisture.

specialboy

http://www.vent-axia.com/product/locarbon-pozidry-positive-pressure-unit.html

We had one of these fitted a few years ago and haven't had any problems since.

Smiley_Dan

There could be multiple causes of this, you need to do more exploratory work. Is some damp bridging the insulation? Which insulant was used? Was some missed, creating a cold spot.

Heating and ventilating more is like using a sledgehammer to crack a nut. If energy saving was your goal of fitting CWI, it's not a solution.

macman

By 'surface damp' I assume you mean condensation? Nothing to do with 'drying out': warmer air holds more moisture in suspension, so by having the house cooler, more of the moisture will condense out at night onto the coolest surfaces-usually the outside walls. You need to improve the ventilation, since just breathing releases large amount of water, as does cooking.

changed_username

tony6403 wrote: »

Given that you don't like the house too warm, a good quality dehumidifier will take out the moisture.

I have a top of the range dehumidifier and when condensation appears on the windows (despite having the cookerhood on full power and saucepans covered etc) I just switch it on in Laundry Mode and within 5 minutes the condensation is gone.

Grenage

Condensation is down to too much moisture and not enough heat to hold it in the air; it's normally caused by people drying clothes indoors and a lack of ventilation.

Don't dry clothes indoors.
Do have a bathroom extractor fan that over-runs for 30 minutes.
Kitchen extractors are a bonus (ones that lead outside, not air filters).

Keeping the heating at a lower level for longer periods is normally better than having it on high for a few hours. We switched to keep our at 18C 24/7, regardless of occupation, and there was no cost increase in cost.

Dehumidifiers are a costly way of removing moisture - you're better off buying a heat-recovery ventilator if you fancy the hardware route.