condensation on Double glazed widows

[isoupdragon]

Hi guys, any ideas on why two of our double glazed windows are running with condensation? I have only experienced this before in a cottage we lived in that had single pane windows - not experienced it with double glazed before! The two windows in question also have black mildew growing around the frames and on the edges where they fit the walls. I like to leave my windows open as often as possible and since it is only these two windows that seem affected, I'm hoping there may be a way of fixing them without replacing the whole window (I't a big window!!) A friend did say something about the seals and the Argon gas????? Hope that might mean something to someone Any suggestions would be great, Thanks

 

[big-all]

john d will be along with his link i wont steal his thunder
but ventilation not drying washing and closing doors when showering/cooking and ventilation comes into the equasion

 

[isoupdragon]

Thanks for the thought but the windows I have problems with are both Bedroom windows. I don't dry things in the house (except with a condenser dryer downstairs in an outbuilding that serves as a utility) and have an extractor fan in the bathroom upstairs for when the shower is used.An extractor fan in the kitchen, and the door is usually shut while I'm cooking otherwise the dog and cats want to help I try to open the windows for as long as possible through the day (even when it's cold) and I'm the only one here! I can't think why only these two windows are affected in the whole house

Thanks again

 

[Richard C]

Are the rooms heated? Do you have cavity walls? Does it only happen at night or all the time? Are they bedrooms that are slept in with the windows closed? Do you know the history of the windows; i.e. are they original, replacement, are the openings original or were they formed as a result of later building works, age of windows?

 

[isoupdragon]

Hiya. Yes, both rooms are heated but only for 2 hours Am and 3 hrs in the evening. Both bedrooms are slept in (us in one and my teen in the other) but they are opened in the morning for the fresh air but even then I have to use a squeedgy to wipe of the condensation and then dry off the windows and ledges! The house has cavity wall insulation throughout, and as far as I'm aware, the windows are not that old. We bought the house 4 years ago and I think they were done about 3 years previous to that (might be worth digging out the papers). not in an extension or anything like that, they are both in the original part of the house. The other bedroom, where my 3 kids sleep does not experience this problem despite the number of them in the room and yes it is much worse overnight! We have tried sleeping with the bedroom doors open thinking that might help the circulation, but it doesn't seem to

 

[Richard C]

Hiya. Yes, both rooms are heated but only for 2 hours Am and 3 hrs in the evening. Both bedrooms are slept in (us in one and my teen in the other) but they are opened in the morning for the fresh air but even then I have to use a squeedgy to wipe of the condensation and then dry off the windows and ledges! The other bedroom, where my 3 kids sleep does not experience this problem despite the number of them in the room and yes it is much worse overnight!

You have a lot of people in your house; humans generate a surprising amount of moisture by breathing/sweating etc & the older/bigger the person, the more moisture generated. With modern, air tight double glazing, you should always have a small window partially open in each bedroom at least for part of the night. It could also be that because of the way your heating the rooms, the ambient temperature isn’t getting high enough to raise the dew point before the room is used for sleeping.

We have tried sleeping with the bedroom doors open thinking that might help the circulation, but it doesn't seem to

Leaving the doors open won’t help much, it will just distribute the ambient moisture around the property, you need some windows open.

The only other cause of excess moisture could be that you have a breach between the inner & outer cavities in the two rooms in question as a result of poorly installed double glazing. This would allow moisture to migrate form the outer cavity to the inside of the property but my guess is your problem is down to lack of natural ventilation.

 

[isoupdragon]

Thanks for all your help - not sure what else I can do on the ventilation point as I have windows open often as possbile, but at least now I'm hopefull it's not the expense of having to replace the actual windows

thanks again