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I live in a 10 year old house in Southern Wisconsin. The windows are double hung, double-pane low-e glass with self-storing storms. We get a lot of moisture condensing on the inside surface of the storms, but none on the inside of the double-pane. There has been so much moisture that some of the storms wood is deteriorating.
This was happening mostly last winter, though we just had a minor cold snap and it happened then too. We keep the moisture inside the home fairly low in the winter, like 20% or so.
The condensation is especially bad in the master bedroom, which is on the NW side of the second floor. There is almost no condensation on the lower floor, or on other second floor windows. The double-hung windows are the kind that pull out for cleaning.
My question is, could the double pane glass have lost it’s seal, or is the seal around the window frame bad? There is no visible moisture at all between the panes of the double-pane, and since there is no moisture on the interior window surface it doesn’t seem like just a matter of high interior humidity.
Any suggestions? Thanks in advance,
Phil
Replies
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Condensation occurs when warm, moist air bumps into a cold surface. I'd say your window is leaking warm, indoor air to the storm window.
*Ok, Fred, here goes:Lock on the door: yes, but the door is only closed at night.No sloped ceilings.The return air uses stud and joist spaces.Each bedroom has its own high-low return ductwork, so no return in the hall.Full unfinished basement, no crawlspace.Two children, 5 and 2 years.We had an Aprilaire installed last winter, but the problem predates that. I probably should also note that there is a master bath off the master bedroom, with a full tub and shower. There is a functional exhaust fan, which vents outside, not just into the attic. We use it pretty religeously in the winter months.Any clues?
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Before Freddy, Wizard of Weatherization, checks in, I'll take a stab at what he might say (I've been trying to understand his deductive thinking this past year or so):
First, parenthetical condemnation of the humidifier and stud bay returns.
Second, your house has a "stack effect" going, where warm, moist air (relative to the outside) is exiting through your leaky windows and outside air is infiltrating elsewhere. Also likely your air circulation system is imbalanced with inadequate returns on that floor, or the returns are sucking in outside air (heaven forbid they are in the ceiling joists?), pressurized the space and worsening the leakage. try leaving your bedroom door ajar at night to see whether it makes any difference.
Whether the condensation occurs on the window or storm doesn't tell you much -- condensation is just a question of temperature an humidity. When air of a certain humidity hit a cold enough surfaces, it sheds the excess water it can no longer hold. The storm, of course, is going to be pretty cold, a lot colder than the interior pane of a decent window next to it.
Now, why he asked about the children and the lock is most perplexing.
Do deal with this rot soon -- we have the same problem upstairs and I haven't yet explored how far the damage goes below the sill.
How'd I do? This is better than The Hound of the Baskervilles.
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Hmm, the overpressure theory does sound feasible, except for one more bit of data: yesterday was a beautiful fall day with temps in the low 70's. AC did not kick on all day, nor last night of course. Neither heat nor humidifier has been turned on yet, naturally. But this morning we had the worst condensation yet. There were no excessively strong winds either. So, I don't see what could have been causing the exfiltration. Still I admit I can't think of any other reason for such a moisture buildup between the storm and the window.
I'll try leaving the door open a few nights to see what happens.
What about replacing the windows with a better brand? The builder obviously cut some corners on some things, and I think the windows are one of them.
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Now, if it was so beautiful, why didn't you open the windows!!! This is the air conditioner philosophy that makes me so against central air -- once you have it the windows aren't used any more. OK, maybe you have allergies...
Stack effect could still provide the pressure. Also, if the air was humid (whether naturally or by humidifier) it would take little to cause condensation. We've had same weather (DC area) with substantial temp. drops at night. (Because the windows were open, the cats were extremely chummy by morning.)
*Here's a long shot:Any plumbing in or near the stud bay by/below this window? Maybe there is a minor leak that is fueling the moisture in this isolated area.Steve
*Or, to carry Freddy's line of thinking, perhaps his love life is too ... steamy.
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Oh, so THAT's why leaving the door open might solve the problem! And here I thought it had something to do with airflow.
Steve: nope, no plumbing in there.
Andrew: who says we didn't have the windows open? We did, but we closed them at night.
Ok, so last night we had no heating or AC going, bedroom door open, no wind, and no (ahem) steam production going on. This morning the windows were just as foggy as previously. I went around to the other windows, and it really seems to be just these two (Master BR and Master bath). So, it seemas to me that the seal on these two must be really wimpy or nonexistant.
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I live in a 10 year old house in Southern Wisconsin. The windows are double hung, double-pane low-e glass with self-storing storms. We get a lot of moisture condensing on the inside surface of the storms, but none on the inside of the double-pane. There has been so much moisture that some of the storms wood is deteriorating.
This was happening mostly last winter, though we just had a minor cold snap and it happened then too. We keep the moisture inside the home fairly low in the winter, like 20% or so.
The condensation is especially bad in the master bedroom, which is on the NW side of the second floor. There is almost no condensation on the lower floor, or on other second floor windows. The double-hung windows are the kind that pull out for cleaning.
My question is, could the double pane glass have lost it's seal, or is the seal around the window frame bad? There is no visible moisture at all between the panes of the double-pane, and since there is no moisture on the interior window surface it doesn't seem like just a matter of high interior humidity.
Any suggestions? Thanks in advance,
Phil