Moisture on Windows


Old 01-06-12, 02:05 PM
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Join Date: Oct 2005
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Question Moisture on Windows

I would be interested in anyones comments. To give the full picture I am in the Northeast and have a whole house humidifier. Additionally the house is heated by forced hot air.

We have double pain windows. During the winter months we slide down "storm windows" to replace screens. At this time of year I have noticed MOST (not all) of the storms have a significant and noticable amount of condensation/fog on the inside glass. It's been there for years and is not really a new problem. Possibly the number of windows with condensation has increased this year or is more noticable. One item of note, we recently did a significant upgrade to our attic insulation and ventilation. Which was poorly insulated when the home was built.

Whether this is a factor or not I am can't be sure. Is this condensation just a case of poor windows (approx 19 yrs old) that are leaking? Or is there something else that's a factor I am missing?

Thanks for your time.
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Old 01-06-12, 03:45 PM
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You likely have warm moist air leaking around (or through) your windows. Adding insulation might have raised the RH a little, causing the increase in condensation that you see.
Old 01-06-12, 04:29 PM
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Your storm windows do not enjoy the isolation that the space between the double pane windows do, thus there will be moisture that gets in there and needs a way to get out. Storm windows should have drain holes at the bottom to allow water to drain out. These holes can also help to ventilate the space between your windows and the storms and reduce the moisture content. Cold air is typically very dry. To help this drying process, open a couple of the storms a bit to see if they can dry out. Then close them to see if they continue to have a condensation problem or not. If they do, then XSleeper has the answer, humid air leaking out around your windows.

If your double pane windows are double hung, they do leak. If you have painted trim, the perimeter can be caulked and sealed. If stained trim, you might need to remove it and foam between the window and the framing.

As for the double hung portion leaking, some of the seals can be replaced, but unsure if that would be an improvement. A simple improvement that can also help pinpoint the source would be the plastic covers that shrink into place.

Old 01-06-12, 04:30 PM
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What he said..............the main windows are leaking warm moist air into the space with the storms. The cold storm glass then condenses the moisture.

What kind/brand of windows, age, manufacturer?? Whatever the device for sealing the sides, it is not working as it should. Also, if double hung, the latch should be latched. This pulls the two sashes more tightly, for less air migration.
Old 01-08-12, 07:49 AM
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Thanks for the replies thus far. To answer a few of the questions and items presented. The windows are Rivco and approx 19yrs old. They are double hung and double pane. Each of the windows affected by the condensation are latched. As Bud mentioned the storms do have weep holes in the sill. They definetly work as expected when rain enters during the summer months. Allowing the water to properly drain.

It sounds like the belief is the area around the window casing is allowing warm air to leak and condensate on the storms? Would the only (best) solution be to remove the casing trim? Insulate and then re-attach.
Old 01-08-12, 08:30 AM
Join Date: Oct 2008
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It is not just the window to construction framing that leaks, double hung windows, especially older ones, leak a little bit everywhere. If you dig when you shop for new windows you can find the mfgs number on air leakage, and that is just the window, not the trim and frame. And that is for new windows before the wood drys out, assuming there is wood. That is why the shrink plastic option was suggested as it would stop the net air flow of warm moist air around those window sashes.

Now, I have never pulled a window apart and tried to tune up all of the seals, but that might be an option. Some of the window pros might comment as to the potential success of this effort and the availability of needed materials.

Old 01-11-12, 08:16 AM
Join Date: Jan 2012
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This happens when the materials used around the edges of the window pane is too conductive (ex: aluminum or other conductive metals).
Even if the glass is energy efficient, the frame and spacer material may not be. The temperature can seep through and cause frost or condesation on the glass, which is what it sounds like you're describing. I found a little information at *****. There are some other links in there that explain it a little more.

Last edited by Shadeladie; 01-11-12 at 08:57 AM. Reason: Advertising and blogs not allowed

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