Condensation on inside of home glass

Old 04-18-07, 01:33 PM
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Condensation on inside of home glass

I had a home built in September 2003 and have dual pane windows. Since the very first winter we have had major condensation on the inside glass, (not inside of the glass, but the part that is inside of the house).
I called the builder to check it out, because there was ICE forming on my windows and the condensation covered over half of the window. They looked at it, but said that it may be because it was a new house and there may be moisture in the foundation. This problem should reduce over time and I shouldn't be worried about it. The next year, I had the same amount of condensation and ICE on my windows.
We keep our heater at 70 degrees until we go to bed then it goes down to 65 degrees. We don't run a humidifier either. There is only 4 people in the house and we do not take long hot showers or do laundry everyday.
I keep getting the same response from the builder that there is nothing that they can do, because they don't know why this is happening.
What can I do to fix this problem? I have black mold on the window ledge inside of my house and do not want my family to get sick.
Thank you
Old 04-18-07, 03:31 PM
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There is a direct corolation between the inside temp/humidity and outside temps and the insulation value of the glass with regard to condensation. For any given outside temp, glass with poor insulation value will cause condensation considerably more quickly. I had an article in a trade magazine that had a graph, very telling, but I can't find it. Your windows are double glass, but are they Lo-E, or argon or other gas filled, etc?? Lo-E/argon had the best of double glass windows, triple glazed with additional coatings went way up. Plain double glass did not rate much above single glass. What is the humidity level in the house when you have problems??
Old 04-18-07, 03:46 PM
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There are several factors at play here.

First and foremost, the humidity in the home is too high and needs to be reduced. That is the bottom line. Second, the glass is cold... so the insulating glass units (IGU's) evidentally do not have a very good u-factor. Could also be cheap inefficient builders' grade windows. There also could be air infiltration around the windows which would make the window colder than normal. You didn't say what type of windows they are- aluminum, vinyl, wood, but that may have something to do with it too. Third, the colder it gets outside, the greater the chance for condensation, especially when it's too humid in the home. Fourth, there may be a problem with air exchange, causing the humidity levels to skyrocket when the house is closed up in the winter.

If you keep the drapes or blinds pulled, or you do not have forced air heat moving air over the windows, this would also aggravate the problem because the windows would get colder and colder, increasing the liklihood of condensation.

My first inclination would be to suggest you contact an HVAC specialist who can help diagnose why the humidity levels are so high. In all liklihood you need more fresh air introduced to the home via air exchange. And if your heater has a humidifier hooked up to it, it needs to be shut off!
Old 04-18-07, 03:51 PM
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The experts usually recommend that humidity be maintained between 35-55% year round with temperature around 70 degrees. You can pick up a hygrometer where they sell thermometers. Humidity will vary from room to room, with kitchen and baths being higher. Running vent/fan units during and after showers for about 20 minutes will reduce humidity. Running vent/fan during cooking and afterward for 10-15 minutes will reduce humidity in the kitchen. Excess humidity levels can be reduced with dehumidifier. Fans will improve air circulation so that heat is evenly circulated.

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