Mold on Window Casings


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Old 01-22-05, 08:03 AM
jcook48420
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Mold on Window Casings

I have a mold problem on almost all my window casings in the winter. They are made of wood and moisture builds up on the windows during the winter. I live in a tri level and this problem is on the main floor and the upstairs but not in the downstairs family room. We have put in a new furnace with humidifier and air purifier on it but the problem is not solved. Any suggestions would be greatly appreciated. Thank you.
 
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Old 01-22-05, 03:55 PM
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Dear friend,

Sadly, your problem is likely due to a number of contributing factors.

1). Inefficient windows.

Windows that have a high U-factor (measure of thermal conductivity) are not very energy efficient in cold climates. Basically, what happens is they conduct the cold to the inside of your house, where moisture can condense. It is similar to the sweat that forms on the outside of a glass of ice water. This moisture is the reason why you have mold on your woodwork.

This problem may be exasperated by inefficient glass (single pane vs thermal pane) (clear glass thermal pane vs high performance thermal pane) and so on. Thermal panes are warmest in the center of the glass and coldest on the edge. (They are even colder on the bottom edge, since cold air falls down the glass to the bottom.) It is likely that your mold is worse around the edge of the glass, right?

Another factor is your drapery. Keeping the drapes pulled may make you feel warmer, but it actually makes your windows even colder, since they are not being warmed by the ambient air in your house. Colder windows mean more condensation. Pulled drapery also blocks air flow over the windows. (Most houses with forced air heat have heat registers located near or below the windows for this very reason). Air from your heat registers needs to flow over your windows in order to keep them warm and dry.

2). High humidity inside the house.

Running a humidifier is counterproductive to your desire to reduce mold. Mold spores are present everywhere, but they will only become active, or grow, when the humidity reaches a certain level that is conducive to their growth. I would suggest buying several de-humidifiers instead. The reason you do not have the problem in the lower level is likely because warm moist air rises, or you have an imbalanced cold-air return system.

High humidity will increase the likelihood of condensation on your glass and woodwork since high humidity will raise the dewpoint.

3). Poor installation.

I would doubt that this is a problem, but it is something you could check. Remove a piece of casing (the 2 1/4" trim that surrounds your window) and see if there is any fiberglass insulation around the window frame.

Abnormally drafty windows could be causing an unusual amount of cold air to enter your home around the window frames. When this cold air hits the warm air in your house, it will condense. It could also lower the temperature of your woodwork sufficiently to cause your problem.

4). It's too damn cold outside!

No matter how good a window is, it will sweat if: a) it is cold enough outside. b). if there is moisture in the air. (all air has moisture).

If your mold problem goes right up to the glass of your windows, my guess is that the humidity in your house it too high.

If the mold is only on the casing, (the trim that you have to cut around when you paint your walls) then it may be a lack of insulation.

We recently replaced all the windows in a house that was only 8 years old. It sounds like they had the exact same problem that you have. I hope something I've said will help you diagnose your problem.
 
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Old 01-23-05, 06:39 AM
jcook48420
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Thank you so much for all the suggestions. We will look into them and see if we can come up with something short of replacing all the windows at this time. We have only lived here for four years and each year it gets worse. We are in a very cold climate and lately we have been hit with extremely cold temps. and snow. Thank you again.
 
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Old 01-28-05, 07:41 AM
mcp
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I'm having similar problems but different factors.

The house is 40 years old. All windows are double pane. Only the casement windows are sweating (to the point of puddling on the coldest days). All the windows seem very solid and tightly sealed.

1. I replaced the glass in 2 of 4 casements with low-e argon filled glass, hoping this would help. It didn't. It's the same as before.

2. The windows aren't drafty at all. The seal really seams tight on all of my casements. I feel no leaking air at all.

3. Two of the windows are directly over heat registers, and one has no shades or drapes. They both equally sweat.

4. None of the double hung windows have this problem. Not even a slight fog. Totally dry.

I know it's going to sweat when it's really cold (like it is now), but I get condesation even when it's in the 30's outside. Would replacing the entire window be the next step? They're wood. Would new wood windows be better?
 
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Old 01-28-05, 09:37 AM
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MCP,

The glass in casement windows is usually set back several inches farther than it is in double hungs. It's amazing what a difference a couple inches can make in the temperature of the glass, and in the airflow.

You mentioned that you had the glass replaced with low-e argon IGU's. (insulating glass unit) Between the 2 panes of glass, there is a "spacer bar". You can see it when you look around the edge of the IGU. The spacer bar can be made of several different materials. The most common is aluminum. Aluminum conducts cold. And since cold air falls, the bottom of your window is the coldest. Air rising from your heat register also "misses" the bottom edge of your window, because warm air rises, and casement window glass is usually set back at least 4 or 5" from your wall surface. So the bottom of the window is where you will notice the most condensation.

Take a look at the IGU's in your double hungs, and examine the spacer bar in them. Is it aluminum? or is it a black rubber looking product? Often, the black spacer bar is a brand called Swiggle, and it is a little better than aluminum because it is not metal and will thus conduct less cold on the IGU edge.

Replacing the glass is likely not the solution. We often use a product called "heat mirror", which is one of the most efficient glass options, and sometimes our heat mirror glass will also get moisture on the bottom.

If you do replace your windows, and you want to avoid the sweat, I would suggest the Pella architectural series. Their casements have an IGU on the outside, and then an additional "storm" window on the inside. (you often see these windows with the optional mini-blinds installed between the glass). I've never seen one sweat, likely because of the 3rd pane of glass, which acts as a buffer to the comparatively colder outer glass.
 
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Old 01-28-05, 12:21 PM
mcp
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I'm pretty sure it's aluminum in the casements, and I'm not sure about the double hung.

How much better are the heat mirrors than what I most likely have? Again, I'm getting puddles of water with the temperatures we have now (in the teens). Is it worth trying on one window? Can I order them from someone and put them in myself?
 
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Old 01-28-05, 01:27 PM
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It is hard for me to say how much better heat mirror is. If you have Adobe Acrobat, the following .pdf, on page 28, might explain it best. (They take a long time to load.) Look at the chart that compares the standard IG to Heat Mirror TC88. http://www.southwall.com/products/pr...tionBinder.pdf

The sale and distribution of Heat Mirror is limited to licensed dealers only, so you might have a hard time finding it. Perhaps calling around to a few glass houses and asking might not hurt. Otherwise, look at: http://www.southwall.com/fabricators.htm and see if any of those dealers are in your area. I'm not sure whether they will sell retail or not, you'll have to find that out yourself. We get ours from one of their fabricators, Thermal Line Windows in Mandan, ND, but then we are one of their dealers.

Southwall technologies also has a new product called Superglass Quad, which is supposed to be the cat's meow. It is so new that there are very few dealers out there right now, but perhaps you'll be hearing about it more in the future.

As far as changing the glass yourself is concerned, I'd have to say that it probably is not something you could do yourself. I'd recommend calling a Glass house and getting an estimate.
 
 

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