Excessive condensation on Windows throughout winter

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Posted by: from Bradford
11/2/2012 at 10:16:36 AM

Looking for suggestions on how to resolve this issue. We have been in the home for seven years and it's been an issue since day one. As soon as it gets a little cold, we have condensation build up on our windows. I see the same issue throughout our area, with many different builders. Not sure if it would be the windows themselves, but our humidity in the home is high - our winter levels are like summer values.

Do you believe a de-humitifiry would assist? We have tried to keep our bathroom fans on and the fan on the furnace running that seems to help a little. We keep a few windows open as well and that helps a little as well. Any suggestions would be great.

Thinking of getting a De-humitifiry + small one and see if that helps at all, then possible look into a version for the home down the road.


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Date/Time11/2/2012 at 3:29:07 PM

Good Afternoon:

I had a similar problem with a home that was built in the mid 90's. It had aluminum windows and baseboard heat. I alleviated the problem by installing two ceiling fans: one in the rec room downstairs and the other over the stairway leading upstairs. These fans never shut off and they kept the house quite a bit dryer. We have boats which condense up quite a bit and we resove the issue with fans and a dehumidifier. A small one will not do the job except in a localized area. Air movement and extraction of the air will be the only solution to your problem.

I would get a reputable furnace installer in to give you a quote on a central dehumidifier that is capable of the square footage of your home. Also, installing fans will help as well.

Another issue is even heat in the house. If you have a situation of dampness and condensation, then there is the possibility of mould starting. Make sure that you pull any large items such as dressers, if they are on an outside wall, away from the wall a couple of inches. That will allow air movement behind them. Check as well, any closets that are on an outside wall, for they, if closed will not have enough circulation of keep dry. Once the humidity issue has been lowered then you will not be as prone to mould starting. If you have any signs of mould at present and it has not penetrated into the gyprock, take a solution of 10 % bleach and water 90%, spray, allow to stand for a couple of minutes and then wipe dry.

Good luck resolving your problem.


Meadowood Homes

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Dennis from Kelly Interior's in Georgetown
Date/Time11/2/2012 at 3:34:34 PM

I have installed a whole home de-humidifier and it has resolved the problem you have.

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Date/Time11/2/2012 at 3:35:42 PM

Hello Davis,

The humidity is generally higher in the fall and the winter time. However the condensation problem is only caused by your poor windows. The glass is cooler than in the summertime so the higher humidity condenses immediately when it hits the glass surface. Only if your glass has the same temperature like your room, it would not condensate. That means, when you replace your old windows with new isolating glass windows you won't have this problem anymore. De-humitifiry would help, however it would not solve your problem.

Please educate yourself a bit more here:


3D-Tile-Design - Bertram Tasch

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Date/Time11/2/2012 at 3:54:43 PM

I would suggest a de-humidifier model that attaches to your furnace duct work.

But you didnt mention what type of windows in home, could be them also.

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Date/Time11/2/2012 at 3:57:05 PM

Sounds like you have researched a little on the condensation already.

The best thing for windows is air circulation. Older homes never had these problems because they were not as wrapped, weatgher proofed, insulated, vapor barrier and air tight as our new homes.

Make sure too that heavy blinds don't restrict air movement. As well you could look into the type of glass in your windows.(do your windows have lowe-e glass, argon gas injected as well as type of spacer bar used in the sealed unit) when glass is cold outside and the house is warm it will create a dew point.

Aluminum or steel framed windows are allowing a cold transfer which creates even more condensation. Single pane glass adds even more window condensation. Vinyl windows with the right glass (sealed unit with Lowe-E) can help sufficiently reduce this problem.

You can tell if your windows have Lowe_E glass just by looking at your window during the brightest time of day. They should look tinted and extremely hard to see through.

Hope this is helpful

Excessive condensation on Windows throughout winter
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Date/Time11/2/2012 at 7:51:10 PM

First off, humidity levels are always lower in the winter time. That is why most homes have a central humidifier attached to the furnace, to raise the humidity level in the winter. Do you have a humidifier? If so it's set to high and should be turned off in the summer time.

Your bathroom is another source of humidity as you know. Try replacing the fan on/off switch with a timer switch. Also is your fan actually pulling air out of the room? Hold a tissue up to the grate and see if it sticks.

Old leaking windows will condesate very easily as previously mentioned. Creating air flow over them helps with the condensation, but doesn't solve the problem.

Do you have a sump pump in your basement or a high water table? The extra humidity may be coming from your basement. That is were I would put a portable de-humidifier first to see if that helps your situation.

Try placing a humidity meter in various places in the home at the same time, you might be able to narrow down were the highest levels are. A whole home de-humidifier will help and proabley solve the problem, but I would be interested in finding the source and fixing it properly.

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Date/Time11/2/2012 at 8:53:36 PM

We have dealt with this problem with new homes up to 10 yearsw old and have found that there extreme gaps behind the calking of the windows. This needs to be filled with foam then re-caulked. We then asked customers to put in a humidifier which helped get rid of the moisture and ice build up on the windows.


Michael Sorrenti

Muskoka Wood Decks & Fencing

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Date/Time11/3/2012 at 9:41:29 AM

A de-humidifier wouldn't hurt. Fall is the worse time for condensation on windows as humidity gathers in your home all summer and when the weather turns cold it deposts on the coldest place in your house(your windows) are your windows flush with the inside walls or are they set out. If you have builders windows that certainly would not help either.

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Date/Time11/3/2012 at 12:37:06 PM

Hi there,

We know that condensation occurs when cold meets hot. If this I on going, my suggestion would be to spend the 300.00 on a thermal energy audit report, make sure there using flix equipment for thermal imaging, and provide a full report, this will determine if the glass if your windows have lost its Argon gas, this could be the main cause. Before you go out and buy that humidifier.

Good luck

Joey (Tiger) Arruda

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Date/Time11/3/2012 at 1:30:05 PM

I would suggest having a company that installs windows address your dilemma. I am a carpenter and can not correctly advise you.

Thank you

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Beatrice from Bio Solutions Inc in Coquitlam
Date/Time11/5/2012 at 11:34:02 AM

It's hard for any of us to properly diagnose the situation online. There are MANY variables missing from the equation that you may not be aware of as possible factors. But you are on the right track. The age of your home is one of the single most important factors, but what you always must consider is that your house operates as a system, and fixing one issue or upgrading one component may not solve the problem but may just serve as a band-aid.

Start with minor improvements following advice from to winterize your house. As you work through the articles and checklists you mat start to see where you can improve these systems yourself before you need to hire a contractor.

Your single best weapon against condensation, and maintain good air quality in the home, is ventilation (but close the windows on rainy days). Keep those fans running until the relative humidity falls below 50% as anything higher contributes to mould, dust mites, and other insects. Spiders are a great clue to where you may have moisture issue as they go where there is food and insects tend to be around wet wood. I could really go on forever but I'll let the CMHC do the talking. You will find ample information there.

Good Luck!

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