Really bad condensation problem

[Crag]

Hiya,

I'd be grateful if someone could advise on how to rectify the condensation problem I have.

I live in a 60s built semi house, with recently professionally installed cavity wall & loft installation and 10 year old double glazing. I have always had a really bad problem with condensation in the autumn/winter months and this year is no different - it literally drips down the windows (upstairs only mind) and pools on the window sills once the heating has been on. Surely this shouldn't be the case even if there is a big difference in temperature between outdoors and indoors?

Looking at neighbouring properties nobody seems to have the same problem (or at least not to the same extent) as I do.

Once again, grateful for any advice and views.

Thanks.

[Rusty Nail]

I had the same problem with a ground floor flat i bought in December last year. the double glazed windows were relativly new, but the condensation had been so bad that the wooden window ledge had mould on it. When i removed the window ledges i discovered a 10mm air gap below the window direct to outside.

I used external silicone to seal the gaps and injected expanding foam into the space once the new window ledges were fitted.

End on condensation problem.

[Andrew Gabriel]

The windows are probably the coldest surfaces in the house, and therefore the points where excess moisture is going to condense out. So the question is why do you have excess moisture in the air? Possible causes are lack of ventilation, or a source of excessive moisture. Showers and cloths drying are possible sources. Might be worth getting a humidity guage (small one for a greenhouse will only cost a few quid) to see what the humidity is in the rooms affected (don't measure near the window).

[Curious]

Cooking with gas, tumble dryer not vented to the outside, no extractor fan in bathroom/kitchen, and generally poor ventilation, are possible factors to consider. Bedrooms are prone to condensation because we breath water vapour out all the time, probably equivalent to between 250ml and 500ml of water each per night. Double glazing doesn't necessarily prevent condensation. The sealed units may have failed but I don't know how you can check for that. If you can't find the cause(s) and fix them, you could consider dehumidifiers.

[Ed Sirett]

I've met this before a couple of times in the era of property. The DG has removed the draughts and the required minimum ventilation. I'd hazard a strong guess that the DG units don't have trickle vents?

You'll just have to improve the ventilation and/or add extractor fans in the bathroom and kitchen.

[Dave Plowman (News)]

You must have a source of water vapour in the house - far greater than the ventilation can cope with. So you need to increase the ventilation in the areas it is usually caused in - things like bathrooms and kitchens. Unvented tumble driers and cooking are the usual suspects. An extracting cooker hood should sort both. And leave at least some of the ventilators above the new windows open - especially in bathrooms and kitchens, etc.

[Dave Plowman (News)]

Aren't these required by 'law' these days?

[Dave Plowman (News)]

Ah - just re-read the post and noted the older double glazing. New double glazing requires ventilators above each window. So it sounds like simple lack of ventilation.

[Curious]

Mmmmm, that's interesting. None of the DG in my neighbourhood, including mine, installed by a variety of firms in the last couple of years, has any ventilators.

[Crag]

On Sat, 18 Nov 2006 08:56:24 GMT Crag wrote in news:Xns987F5B0DB7914gd0azdcdu@212.23.3.119:

Thanks for all the replies. Will look into improving the ventilation in all the rooms upstairs...

[Andrew Gabriel]

When I had mine done (just before Part L came in), trickle vents were only required if the windows didn't have a lockable trickle/ slightly open position, which most do. The installer said LA's and housing assocations insisted their properties has trickle vents in the DG because tennants tended to do things which generated excessive moisture resulting in damp, but private households usually preferred their windows without. It made negligable difference to price.

[Crag]

On Sat, 18 Nov 2006 11:32:17 GMT Crag wrote in news:Xns987F757C36C7gd0azdcdu@212.23.3.119:

Thanks for all the replies. Is it possible to have trickle vents fitted into DG after they're fitted? Are there any PVCu installers that offer such a service?

[Rob]

And as an ex-LA/HA worker, I can put on record that residents have been known to stuff the trickle vents with tissue ;-)

I do wonder what social housing tenants do that private occupiers don't ..!

[Dave Plowman (News)]

Ah. My only experience of UPC double glazing is the unit I bought from Screwfix and installed myself. It came with fitted but closable vents above the window and something about it being a requirement

[Dave Plowman (News)]

Some, at least, appear to be an add on unit which would require enlargement of the opening, or a smaller window.

[Guy King]

The message from "Dave Plowman (News)" contains these words:

Yes, but possibly not when they were installed.

[Guy King]

The message from Rob contains these words:

The front walls of the houses round here have vents fitted because of the gas cooker and the gas boilers in the kitchens. Many of these are blocked - some with tape, some with foam. In some cases it isn't important because the boiler's been replaced with a balanced flue unit and the cooker's either got enough ventilation from elsewhere or is electric. However, in many others it's still needed. So far no one seems to have died from it.

I can see why they do it - the howling gale round your withers when you're washing up is bad enough, but on really cold nights the back of the washing machine can freeze.

[Ed Sirett]

Be at home more for a start. Do more indoor drying of clothes. Have a greater population density per unit volume of the dwelling. etc.

[Ed Sirett]

Mine don't (installed 1992) but then most rooms have an air brick.

[Owain]

Breed like rabbits, leading to

Owain