Double glazing / condensation

Haych

Soz, think this could be a long story but here goes.......

About five or six years ago I had all the windows in the house replaced by a reputable (or so I thought) and local company.  I know people who have used them and I've not heard any complaints.

The installation was a bodge job in my opinion and I had to call them back many times due to excessively loud wind noise after the installation - even a mild breeze would result in the windows howling.

After about the fifth or sixth visit I finally spoke to somebody in the company who seemed to know what he was talking about - when the new windows were installed the installers left the cavities open and just covered over them internally with uPVC cladding so when breeze entered through the air bricks it was blowing through the cavity and finding its way out via the new frames somehow.

He rectified the situation by removing all the cladding and squirting copious amounts of expanding foam into the cavities before tidying it all up again.  This made things better but didn't eradicate the problem completely.  He then added an extra piece of external quadrant around the frames which has finally made the wind noise abate, or as good as.

That's just a bit of a back story and not the reason I'm posting - I just thought it might serve useful information for my next question/problem.

Despite the windows being A++ energy rating (or that's what they claimed them to be) I get an awful lot of internal condensation on the window panes, even when the weather is only slightly chilly outside - I'm talking about 10C or so and condensation will start to form.  The old windows used to as well but they were cheap, old, and well shot when I moved in.

I keep the house well ventilated and even keeping the bathroom window open on night vent works well at keeping the room ventilated and dry, so the other rooms shouldn't hold excessive moisture.

I also don't notice any other houses in the neighbourhood having condensation on the windows, and I do look.  In any other house I've lived in I've never noticed a similar problem, even comparing to my folks house whose windows are 30+ years old and they don't have any issue with condensation forming.

So, naturally I'm starting to believe that the windows have a massive thermal bridge somewhere in the design and the warm air inside the house is condensing on the cold glass surface, particularly around the edges of the windows, the bottom edge of the glass can have several inches of condensation on a really cold morning.

That can't be right for a modern double glazing system, can it?

In anticipation of being asked, none of the windows have trickle vents - but then neither do my folks windows and as I've stated, they don't get any condensation at all.

The windows are still under guarantee so I'm wondering whether this is normal and whether I should make myself a nuisance to the window company again.

TIA

EDIT: If I leave the windows open on night vent (second locking position) they will still condense.

Fretwired

This might help - I get a bit of condensation every now and then.

http://www.windowsonlineuk.co.uk/blog/double-glazing-get-condensation-inside/

Haych

Fretwired said:

This might help - I get a bit of condensation every now and then.

http://www.windowsonlineuk.co.uk/blog/double-glazing-get-condensation-inside/

Hmm, interesting stuff - thanks for the linky.  It's helped to explain a few things.

ronnyb

I live in a bungalow and condensation and steamy windows, particularly in winter is always a problem. Houses now are well insulated and this makes the problem worse because the moist air has nowhere to go. Good ventilation is a must but reducing the amount of moisture has an effect. Don't leave wet washing about to dry and try and reduce the amount of steam when cooking. Have plenty of ventilation in the bathroom when showering or bathing. The worst room in our house for condensation on the windows is the bedroom where me and Mrs Ronny sleep. It faces east so tends to be colder and a lot of moisture is produced when breathing. We leave the bedroom door ajar and leave the windows on vent so it does reduce it. We also have a dehumidifier which does work. The amount of water collected in it if i leave it on all day is quite substantial, easily a litre.      

Haych

I have been thinking of purchasing a dehumidifier for a while.  If the issue I'm having is a natural phenomenon of better glazing then I will be acquiring one in the next few weeks I reckon.

Thanks

Jimbro66

If you are getting condensation on the inside of the windows when the outside temperature is 10 degrees it does rather suggest that air humidity is quite high in your house despite you trying to keep it well ventilated. If you don't already have one it might be worth getting a hygrometer to measure the % relative humidity. You can get combined digital thermometer-hygrometers from Amazon for about a tenner.

If you then find humidity is high you can either take more action to reduce it or (the more expensive option) get a dehumidifier and run it frequently.

If the hygrometer shows the relative humidity to be low/medium you can then look at the effectiveness of the double glazing. If the sealed units are not misted inside they should be OK. Did your d/g units have Argon fill?

Our double glazing only shows internal condensation if the outside temperature is very low (below zero) or when Mrs 66 has four saucepans boiling on the hob with the extractor fan switched off because "it's too noisy"

mbe

I suck it up with a Karcher window vac if the bedroom window is steamed up in the morning. The window is quite large but it only takes about 5 minutes to clear it and it stays free of mist for the rest of the day.

Haych

Jimbro66 said:

If you are getting condensation on the inside of the windows when the outside temperature is 10 degrees it does rather suggest that air humidity is quite high in your house despite you trying to keep it well ventilated. If you don't already have one it might be worth getting a hygrometer to measure the % relative humidity. You can get combined digital thermometer-hygrometers from Amazon for about a tenner.

If you then find humidity is high you can either take more action to reduce it or (the more expensive option) get a dehumidifier and run it frequently.

If the hygrometer shows the relative humidity to be low/medium you can then look at the effectiveness of the double glazing. If the sealed units are not misted inside they should be OK. Did your d/g units have Argon fill?

Our double glazing only shows internal condensation if the outside temperature is very low (below zero) or when Mrs 66 has four saucepans boiling on the hob with the extractor fan switched off because "it's too noisy"

Useful information and advice, thank you - I'll look into it.  Yes the units are argon filled, or that's what they claimed in any case.

mbe said:

I suck it up with a Karcher window vac if the bedroom window is steamed up in the morning. The window is quite large but it only takes about 5 minutes to clear it and it stays free of mist for the rest of the day.

Another great idea, cheers

WezV

Condensation and high humidity were an issue in my house until recently.   An old one with solid walls, modern double glazing and poor ventilation

A PIV unit in the loft has completely solved it.   Humidity has been consistently 50-60% since it was installed - we have no condensation, even on the single glazed original external door

Emp_Fab

Just to clarify, are you talking about condensation that you can wipe up - i.e. on the room side of the window glass, or condensation inside the cavity between the two panes ?

fftc

WezV said:

Condensation and high humidity were an issue in my house until recently.   An old one with solid walls, modern double glazing and poor ventilation

A PIV unit in the loft has completely solved it.   Humidity has been consistently 50-60% since it was installed - we have no condensation, even on the single glazed original external door

Been thinking about getting one of these systems installed.
Did you fit it yourself or have someone in to do it? What sort of cost are you looking at?

JAYJO

i bought a dehumidifier a few years ago. I keep it in the bedroom. I will move it to the hall downstairs or where ever it seems worse. Its a good size(for large 4 bedroom house) and has castors ,dosent need emptying as often but still surprising how much water it quickly collects. You can feel the difference when its running . I would recommend one. All windows need doing in our house.I would recommend  one with a timer.

Fuengi

If I'm reading your OP correctly the windows are installed on the outer skin of brickwork with the cavity to the inner side?

If so this will potentially create a cold bridge. Ideally the window should be set across the cavity with thermal closers around it. 

If you have an insulated cavity the outside skin is cold. 

Haych

Fuengi said:

If I'm reading your OP correctly the windows are installed on the outer skin of brickwork with the cavity to the inner side?

If so this will potentially create a cold bridge. Ideally the window should be set across the cavity with thermal closers around it. 

If you have an insulated cavity the outside skin is cold. 

Yep, that’s about the size of it. 

Fuengi

Haych said:

Fuengi said:

If I'm reading your OP correctly the windows are installed on the outer skin of brickwork with the cavity to the inner side?

If so this will potentially create a cold bridge. Ideally the window should be set across the cavity with thermal closers around it. 

If you have an insulated cavity the outside skin is cold. 

Yep, that’s about the size of it. 

Ok. You could try to add a bit of insulation in the reveal if you can run it into the edge of the frame? 

Say 25mm of insulated plasterboard all the way around, skim and paint. That would partially stop the cold bridge.

On top of that you could clad around the window externally with plastic or timber. Anything that adds thermal capacity to the cold spots will help.

I think you need to try to drive the dew point back towards the outside. At the moment cold air is meeting the warm air in your house and hence some of the moisture.

Google 'Dew Point in houses' for a better understanding. 

ToneControl

I suspect that having the central heating switched off at night and during the day, or having a cold bedroom generally will also increase condensation in a bedroom

bobblehat

fftc said:

WezV said:

Condensation and high humidity were an issue in my house until recently.   An old one with solid walls, modern double glazing and poor ventilation

A PIV unit in the loft has completely solved it.   Humidity has been consistently 50-60% since it was installed - we have no condensation, even on the single glazed original external door

Been thinking about getting one of these systems installed.
Did you fit it yourself or have someone in to do it? What sort of cost are you looking at?


Fairly easy to install yourself.  Just need a 240v mains connection in the loft and cut a 10" hole in the landing ceiling.The unit can sit on joists or on a board.  Unit costs vary but start at around £250. All units do essentially the same job so don't bother with more expensive options and fancy controls.

The condensation on the windows is a result of the high humidity levels in the house. The only way to combat it is to reduce the humidity eg. Fit extract fans in the bathroom and kitchen (and use them) , don't dry clothes indoors or on radiators.Alternatively as above fit a PIV unit in the loft.(Positive Input Ventilation) .This essentially pressurizes  your house and forces the moist air out.Cheap to run and very effective. 
Another thing often overlooked is the temperature in the house. Cold air holds less moisture so your better off turning up your heating a degree or two if you have condensation issues.

uncledick

mbe said:

I suck it up with a Karcher window vac if the bedroom window is steamed up in the morning. The window is quite large but it only takes about 5 minutes to clear it and it stays free of mist for the rest of the day.

+1 for this.  Brilliant tool and was less than £40 on Black Friday.