Wet windows

ritaotaySeptember 27, 2005

Years ago I replaced my old aluminum storm windows with vinyl storms... Every winter since then, on the second floor, water appears on the inside of the inside windows and on the inside of the storm windows then the storms freeze over...

Ok, I was told that the problem was too much humidly in the house... Since then, in the winter, I keep the humidifier set at about 20% until I start getting zapped ( static electricity ) from everything in the house then turn it up a notch or two until it goes away then turn it back down when the windows get wet again and I keep repeating the process until spring comes... All winter long I'm wiping water off the inside windows and watching the ice grow on the inside of the storm windows...

One year I put plastic on the window frames, on the inside, that worked for about a month and then the inside windows got wet and the storms froze over again... If I leave the storm windows open it helps but I can't afford to pay $400. or $500. a month for heating bills... The bedrooms are on the second floor so completely shutting off the heat vents is out of the question... One of the windows is painted shut and it still happens, although the storm doesn't have as much ice as the others...

Well, it's starting again, no ice, just water on the inside windows and on the inside of the storms ... Only I DO NOT have the heat or the humidifier on yet... It only went down to about 45 degrees last night, we were gone all day and most of the night so it wasn't anything we're doing...

I love my house but I can't go through this again and I really don't want to go through the hassle of moving but I'm beginning to think it's my only option... Please, any suggestions?


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No add-on storm window totally seals out moisture. That's why storm windows, whether aluminum or vinyl have weep holes (small vent openings) at the bottom of their frames to allow condensation and moisture to escape. It's not unusual for these to get painted or caulked over ... or plugged up with dirt or even spider webs. Go outside and check the bottom edge of the storm frames to see if those openings are plugged up. If they are, that could be the cause of your problems. Take a scratch awl or even a long nail and poke it through the hole to clear them out. If you're lucky, that will cure or at least alleviate your moisture problem

    Bookmark   September 27, 2005 at 1:33PM
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Well with them being on the second floor and me being a little old lady ( LOL ) I didn't check the from the outside... What I did do was take a 6 oz. glass of water and poured it between two of the windows, the one that get the most ice build up in the winter ( south side ) and the one that gets the least ( east )...

Now here's the odd thing... When I poured the water in the south facing window it drained as fast and I poured it, you can actually see day light under the whole storm window frame, all the way across.... On the window facing east, the one that gets the least amount of ice, it took about 30 seconds for most of it to drain and I had a little puddle in one corner, about a table spoon... Does that mean I should seal up the south facing window for the winter, just part of it?


    Bookmark   September 27, 2005 at 5:21PM
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Hi Rita,

A few questions....

Are these single pane or double pane windows? Storms?

Do you notice a relationship between the time of day and the amount of moisture on the windows?

Is there a difference between upstairs and downstairs windows and the amount of condensation on the window?

What sort of heat do you use and is there a noticeable difference between the upstairs and downstairs when heating the house?

How warm do you keep your home in winter?

How do you measure the relative humidity in your home?

How old is your home and do you know how well it is insulated?

Do you remove the storms in the summer, or are they permanent?



    Bookmark   September 28, 2005 at 7:46AM
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That's an awful lot of questions Oberon, but you may be right in analyzing all the factors to do a more 'scientific' analysis. Nevertheless, the south-facing window shouldn't be showing daylight all across the bottom-- that allows for excessive moisture to seep inside and get trapped. And when cold, moist outside air reaches warm window glass ... it freezes, especially overnight. While Oberon may have other ideas after hearing the answers to his questions, I'd still apply a bead of caulk along the inside bottom (outside would be better) of the frame. Make sure you leave about a quarter inch gap in the caulk in at least two places (try to locate the weep holes) so condensation can drain when the sun hits it during the day.

    Bookmark   September 28, 2005 at 9:06AM
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Mike, there are no weep holes, on any of the windows, just a straight vinyl U shape thingy that you can slide up and down to make the window fit....

Oberon: Single pane windows and single pane storms.

Yes, the windows usually get wet at night, in the winter it stays there all day and night.

I have natural gas heat and yes there is a difference between the upstairs and downstairs temperatures... Hubby says he can't really tell the difference but I can... If I had to guess I'd say, in the winter, there is about a 5 to 10 degree difference, with the upstairs being cooler.

The thermostat is set at 72 in the winter with a 4 degree variation... ( that's the way it works, it can get up to 76 before the furnace shuts off and down to 68 before it comes back on. )

I have a humidistat on the humidifier ( Lobb ) and two 'free standing' ones I use, one in the computer room, first floor, and one in my bedroom, upstairs.

The house was built in 1956 and I would guess some of the wall insulation has compressed over the years but, when I had the roof redone last year, the roofer said he could still see the wall insulation in the dormer walls. ( Looks like white fluffy stuff, not fiberglass. )

The storms and screens are permanent...

Oh, I do have and use exhaust fans in the bathrooms and kitchen.


    Bookmark   September 28, 2005 at 12:04PM
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I guess I should have stated earlier that 'weep holes' aren't readily noticeable vents or openings֖ On aluminum storms, they're usually nothing more than a small 'kink' in the bottom edge of the frame ("the thingy you can slide up and down"). You loosen the screws and slide the 'thingy' down to fit snugly to your sill, thereby limiting how much moisture gets between the two panes of glass, and it won't close up the weep holes. I would imagine your vinyl storms should be pretty much the same.

    Bookmark   September 29, 2005 at 8:45AM
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Hi Rita,

Sorry it took me so long to reply - but, here goes...

The short answer is that you have too much moisture in your house - for your particular situation. Someone else, in a different situation, might have much more moisture in their air and yet they don't have problems with condensation on their windows. I will attempt to explain exactly why.

You mentioned in your earlier post that when you take your relative humidity (RH) down to about 20%, the condensation problem disappears, but when you allow the RH to rise again it returns. Well, there are a couple of ways to affect the RH in your home - which is what you have already realized is related to the problem.

A few moisture-related concepts...

Relative humidity is called "relative" for a reason. RH is a comparison of the amount of moisture in your air versus the temperature of the air. Basically, warm air can carry much more moisture than can cool air. When air, with a specific amount of moisture content, is at the temperature where it reaches 100% saturation, the air must begin to release moisture. 100% saturation is also 100% relative humidity. 100% RH is also known as the Dew Point.

When your local weatherman tells you that the dew point is 65 degrees, he is saying that when the air temperature reaches the dew point the air will be 100% saturated with moisture and that the excess moisture will be "released" by the air. The result is morning dew on the ground, on your car, on the exterior of your home and windows, etc. If the evening temperature does not reach 65 degrees (or cooler of course), then the air will not be fully saturated and you will see no morning dew.

Rita, you mention that your home has some temperature fluctuation in the winter - from 68 to 76 degrees. That really is a very large variation and is a bit wide for what I think most HVAC folks would consider normal. From a safetry standpoint (and I am far from an expert in this area), when was the last time you had your furnace professionally cleaned and inspected? It may be absolutely fine, but I sure would like the opinion of an HVAC pro on the operation of your system...again, I am not expert in that area, and could be totally off-base here.

Imagine that the air in your home carries a certain volume of moisture in the air. When the temperature is at 68 degrees, your RH is going to read much higher than it will at 76 degrees. Generally, RH and dew point are calculated using the metric system - gm/m3 (the 3 is actually "cubed") which isn't important except that I am going to do a few rough calculations to (hopefully) explain part of what I was saying.

If your air temperature is 68 degrees, then your saturated vapor density (or dew point or 100% humidity) is about 17.4 gm/m3. Meaning that if your in home temperature is 68 degrees then your air can hold 17.4 grams of moisture for every cubic meter of air.

If you have that much moisture then you will have 100% RH in your home. But, raise the temperature to 76 degrees and then the RH drops down to about 78% - for the same amount of moisture, but a higher temperature.

If we look at it from the other direction, then at 76 degrees, 20% RH means that you have only 4.5 grams of water per cubic meter. If you lower the temperature to 68 degrees, with the same volume of water, then the RH has increased to about 26% - still very low.

Okay, now what the heck does all that mean, and how the heck do we help you to avoid that water on your windows? Well, we will get to that shortly, but unfortunately, I have to leave for awhile and I cannot finish at this moment. Also, this thing is so long that it is not a bad idea to follow up with another post...makes reading it easier.

Rita, I hope that what I have said so far makes some sense...and hopefully, when I finish this thing it will all come together. My point in going this indepth, is that I have a feeling from your earlier posts that you are someone who likes to know WHY something is happening and is not content to simply know that it is happening. My feeling is that you are not someone who doesn't care about the "why's".

Anyway, more later.

    Bookmark   September 30, 2005 at 7:47AM
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We just built a new solarium with ten storm windows and a skylight. It will not be heated and we have very cold winters here. I don't know yet if there will be condensation problems but would like to know if there is, what we can do about it???

    Bookmark   September 30, 2005 at 6:55PM
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Mike, nope, no weep holes at all... The flat vinyl U shaped thingy rests on a flat piece of aluminum trim on all but one window, the south facing one which is just painted wood... That's the one that gets the wettest... I've tried sliding the U shaped thingy down a bit more ( no screws in them either ) but it just won't budge.... Guess I'll have to get out the duct tape for that window... LOL

Oberon I understand what you are saying, I have a soggy second floor... LOL. As for the temperature fluctuations, it's worked that way since the furnace was installed about 10 years ago... There is a gizmo on the thermostat that I can adjust but when I turn it down, for a lower variance, the furnace stays on a lot longer... BTW, it's the same type thermostat that was originally installed when the house was built, a round one, no brand name on it... I don't remember having this problem when I had the aluminum storms but they rattled and were out so of date that I had assumed that I was loosing heat... After looking at my old gas bills I found out I wasn't using any more gas... But that's neither here nor there... I'd like to find a way to keep the windows clear of moisture and ice so I can see out of them in the winter without burning any more gas...


    Bookmark   October 1, 2005 at 5:16PM
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Hi again Rita,

Heat always travels to cold and wet always travels to dry - (unless acted on by an outside force).

In the winter, the outside air is cold and dry. Cold air does not hold moisture very well. Your inside air, by contrast, is warm and moist - moist being relative to the outside air in this case. That warm and moist inside air wants very badly to equalize with the cool dry outside air, so it is looking for a way to escape from your home.

In the middle of summer, pull a can of something cold and frosty out of the refrigerator and notice how quickly the can becomes wet on the outside. This is condensation caused by the contact between the warm, moist summer air and the cold can. The surface of the can is below the dew point. Trying to stop moisture from forming on the can is impossible because it is some very basic physical laws at work.

Unfortunately, those same physical laws are affecting your windows in the winter when you get moisture forming on the surface of the glass. As Mike pointed out, that gap in the bottom of the south-facing window is like an open invitation for your nice warm inside air to go outside...and in the process, it is drawing lots of nice warm, moist air to that particular window. The warm air is contacting that window and, like the can out of the refrigerator, that window surface is below the dew point of the air inside your home...thus, condensation on the glass surface.

With a single pane window, when the temperature is 0 degrees outside (F), the face of that glass inside is only about 16 degrees. At 16 degrees, it doesn't take much moisture in the inside air to cause condensation on the surface of the glass. And btw, these are center-of-glass readings. Edge readings will be lower generally by several degrees.

If you add a "tight" storm window, then the surface of the inside of the window may be about 40 degrees or so, when the outside temp reaches zero.. This is variable of course - I would guess that the south window probably won't quite reach 40 degrees because of that gap at the bottom of the storm. This means that the south-facing window might exhibit worse moisture problems than other windows.

At 40 degrees, it takes only about 6-1/2 grams per square meter of moisture in the air to reach that 100% RH level, which means that an RH reading of only 30% at 75 degrees is sufficient to have moisture on your windowswhich is consistent with your earlier observation that at 20% RH your windows remained dry, but when you allowed the RH to rise, even a little bit, then you saw water forming on the windows again.

Rita, I hope that the information that I have offered wasnÂt way overboard, but your posts, including the answers to my questions, told me that you were someone who really paid attention to the details, so I have attempted to include many of the "details". Also, I offered a rather in depth explanation because realistically, you have limited choices and I was hoping to be able to illustrate exactly why this is so.

Ultimately, there are two things you can do to help prevent moisture from gathering on your windows  first, you can attempt to increase the temperature of the windows to a mark above the dew point, and second, you can attempt to block the warm, moist air from reaching the glass.

You have already done the second when you used the plastic window film in the past. The fact that you had moisture even then indicates that you may have had a slight leak in the plastic and/or that it was really cold outside as well!

In order to raise the dew point of the windows themselves, you will have to assist your homeÂs heating system by using small fans or, even better, small forced air heaters, close to, and directly facing the glass. I suspect this is not a practical solution, except for maybe the very worst offenders. This "solution" should warm the glass enough to avoid moisture build-up, but at an obvious cost in your energy usage, but it may not do a thing for the water and ice build-up on the storm windows  only on the inside glass.

I would suggest that the plastic window covering (combined with tightening up your storms as Mike suggested) would be the best possible "solution" for your situation. It is far from perfect, I realize, but unfortunately there really isnÂt an easy or inexpensive fix for winter condensation on windows. I wish I could offer something better.

    Bookmark   October 3, 2005 at 7:12AM
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Oberon you are the man!!! Rita I can tell you that Oberon is one of the best people in the Nation when it comes to glass and it's affects. You can find no better source than he can offer. I also suggest a new thermostat!!

    Bookmark   October 3, 2005 at 10:10PM
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Well... Guess I'm just S.O.L.... LOL

Thanks Oberon, I appreciate all the effort and knowledge you've put in to your replies, you've made it clear to me that, with the windows I have now, I'm fighting a loosing battle with the ice build up on the storms... lol

I will try your suggestions this winter and start saving up my pennies for new double pain windows... Yes, with 21 windows it will be a pain... LOL

Thanks All!!!

    Bookmark   October 3, 2005 at 11:10PM
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Thanks Guy! I am at a loss for words! lol

Rita, you are very welcome and I hope that it works out for you.

    Bookmark   October 5, 2005 at 7:45AM
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