moisture build up on windows- outside
#1
07-04-05, 06:18 AM
Join Date: Apr 2003
Location: ga
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moisture build up on windows- outside
I recently moved into a 30+ yr old brick home with updated central heating/air unit and hardwood floors. The unit is located under the house which has a 3-4 ft crawl space. The house has been well kept and maintained. Recently there has been moisture buildup on the exterior of the glass windows and doors. It doesn't appear to be just morning dew but is there all day and night. Is this a common thing for a house this age at this time of the year or do I have a problem somewhere? Or is my problem weather related? I live in metro Atlanta.
#3
07-04-05, 06:46 AM
Group Moderator
If the condensation can be wiped off with your finger, then it it temperature/humidity related. The temperature of the glass may be below the dew point due to your air conditioning, which would create "sweat" or a foggy appearance around the glass.
I would just guess that the conditions would have to be just right for this to happen. 1). High humidity / dewpoint in the 80's. 2). Your air conditioner is set low, or your vents are right below the windows in question. 3). There is very little wind, which would usually serve to "dry" this condensation off the exterior of the windows. I would also guess that windows that are in direct sunlight might not be subject to condensation, since the sun should warm the glass sufficiently to prevent condensation.
That's my theory.
I would just guess that the conditions would have to be just right for this to happen. 1). High humidity / dewpoint in the 80's. 2). Your air conditioner is set low, or your vents are right below the windows in question. 3). There is very little wind, which would usually serve to "dry" this condensation off the exterior of the windows. I would also guess that windows that are in direct sunlight might not be subject to condensation, since the sun should warm the glass sufficiently to prevent condensation.
That's my theory.
#5
07-06-05, 08:18 AM
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The windows are dbl pane and the weather conditions that you mentioned have recently been what you said. The moisture is on the outside and can be wiped off. This is first home for me and wifey. She worried about it but I didn't. 
It's always good to get a second opinion. Thanks for the info. 
It's always good to get a second opinion. Thanks for the info. 
#6
07-07-05, 03:58 AM
condensation
XSleeper is right on. Perfect answer.
Actually, seeing outside condensation on dual pane, LowE windows is a natural occurance and absolutely no reason for alarm.
As XSleeper said, there are particular atmospheric and environmental issues involved, even how cloudy it is at night can affect the formation of condensation on the exterior of windows....or if you happen to have a tree on that side of the house, for example.
Remember that heat always goes to cold. Cold is the "natural" state of things and heat is "artifically" produced. It is warm outside, and that heat wants to get into your house because it is cooler inside.
Well, the whole point of having thermal windows is to keep the cool and the warm on opposite sides of your window. The LowE coating is designed to do precisely that, and in the case of your windows it is working perfectly.
The temperature between the lites of your dual pane window is probably very close to the temperature inside your home because the inner lite does not have a LowE coating and the air between the lites can reach equilibrium with the air temperature in the house.
The outer lite has the LowE coating which blocks much of the exterior heat from passing through the glass. But, the LowE coating, being a series of metallic layers, will cool based on the temperature of the home and subsequently may keep the outer lite somewhat cooler than the dew point of the surrounding air - as XSleeper pointed out - thus allowing moisture from the exterior air to condense on the surface of the glass.
Actually, seeing outside condensation on dual pane, LowE windows is a natural occurance and absolutely no reason for alarm.
As XSleeper said, there are particular atmospheric and environmental issues involved, even how cloudy it is at night can affect the formation of condensation on the exterior of windows....or if you happen to have a tree on that side of the house, for example.
Remember that heat always goes to cold. Cold is the "natural" state of things and heat is "artifically" produced. It is warm outside, and that heat wants to get into your house because it is cooler inside.
Well, the whole point of having thermal windows is to keep the cool and the warm on opposite sides of your window. The LowE coating is designed to do precisely that, and in the case of your windows it is working perfectly.
The temperature between the lites of your dual pane window is probably very close to the temperature inside your home because the inner lite does not have a LowE coating and the air between the lites can reach equilibrium with the air temperature in the house.
The outer lite has the LowE coating which blocks much of the exterior heat from passing through the glass. But, the LowE coating, being a series of metallic layers, will cool based on the temperature of the home and subsequently may keep the outer lite somewhat cooler than the dew point of the surrounding air - as XSleeper pointed out - thus allowing moisture from the exterior air to condense on the surface of the glass.
