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How to Cure Sweating Windows
By: Danny Lipford 
When the temp gets around 35 or below, my windows sweat really bad. It freezes around the frame and I have to scrape it off. Our home is 11 years old, but the windows have done this since it was new. My husband says it is the gas fireplace that we use that does it. I read that too much humidity would cause it, would a dehumidifier help? I have to go around every day and dry the windows. Can you help? -Carol
Carol,
We get a lot of questions about windows sweating in the winter. Here’s what’s happening and why.
When air warms, it expands which allows it to hold more moisture. As it cools down, it contracts until it reaches the saturation point and releases this excess water in the form of condensation.
Common daily activities in your home—such as cooking, showering, using unvented gas heat, and even breathing—add moisture to the air. When this warm humid air comes in contact with cold window glass, it cools and condenses.
To reduce this problem you need to either lower the amount of moisture in the air inside your home, or prevent it from coming in contact with cold surfaces. Here are some suggestions that might help:
- Run a vent fan in the bathroom when you shower or bath, and leave it on for 15 minutes afterward. Be sure it is vented to the outside and has a high enough capacity for the room. Also, be sure there is a large enough gap under the bathroom door to allow air to enter.
- Vent gas fireplaces, or limit their use, and don’t use older unvented gas space heaters.
- Cut down on cooking that produces excess steam.
- Lower your thermostat to 66°-68° F.
- Be sure your clothes dryer is vented properly to the outside.
- Seal up any cracks around windows.
- Replace older single pane windows with double or triple pane vinyl ones (avoid metal window frames since they conduct cold), or add storm windows to the outside of your house.
- If you are still having problems, consider installing a dehumidifier.
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34 Comments on “How to Cure Sweating Windows”
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August 3rd, 2008 at 12:08 pm
I have a double pain window that is cracked on one side. Is there a way to take the one glass pane out and replace it?
November 9th, 2008 at 11:52 am
I live in Sandwich, IL. 60548, and have a bad window sweating problem in th winter. Also my excaust vent fans in two bath room collect water in the hoses and dips back in the house thru the ceiling. When its real cold the underside of the roof get a layer of frost. What can I do to fix these problem. I checked the humidity in the house and it is between 50 to 60% temp outside is 38.
Thank you for your time
Robert Wilson
November 19th, 2008 at 7:45 am
I have excessive moisture condensing and freezing in my 100-year-old Kentucky home with “cheap” double-pane replacement windows. Mold was appearing on the back of some of my living room furniture. I finally placed a dehumidifier in my living room. It helps a lot, cutting down on the amount of window dripping, although I don’t like its appearance & having to run it so much (and emptying it manually).
I think the primary source of my excessive moisture is my earthen cellar and crawl space underneath. A complete, sealed, heavy plastic moisture barrier should be installed beneath my house to keep dampness from rising from the moist dirt up into my house.
I currently don’t have the funds, nor the ability, to physically access the problem area, nor the knowledge to effectively attach a total barrier. Somehow this house has already survived a century of dampness, so I keep my fingers crossed that the dehumidifier will extend its life a little longer.
December 21st, 2008 at 8:10 am
We have all new double pane vinyl windows. They are sweating excessively. What can we do?
January 15th, 2009 at 11:45 am
Are the answers to above questions available?
January 15th, 2009 at 11:46 am
Dear Dan,
Today it is -10 F here in Burlington, WI. But this happens at 30 F as well.
I have double pane windows, the indoor humidy is at 39% and we have water on the windows constantly. The windows today have oblong moisture areas in the middle of each window. WE have done the technique of opening windows to combat the moisture, but see that as leaving the door open and paying to heat the outside. Not a good answer. What we have done is to place small fans to dirently ventilate the norhtern exposed windoows, which are large picture windows.
My question is what causes the oblong moisture area in a window? Is it that the low e-glass with I think is the Argon gas, has gone out or no longer works. The window are about 15 years old.
Any ideas.
Thank you for your time.
Bob Edgington
January 24th, 2009 at 5:14 pm
I live in the Florida Keys and recently had hurricane windows instuled but they sweat alot and what can be done to stop this?
January 25th, 2009 at 9:08 pm
We have lived in our home 4 years now and never had a sweating problem until this year. We live in Star Idaho. The only thing that we did differently this year from any other year was that we closed the vents under the house in the crawl space. which is what I thought we were supposed to do in the winter to help cut down on heating costs. Could this be why we’re now getting terrible sweating windows all of a sudden? Or could we have a plugged vent somewhere?
October 24th, 2009 at 3:48 pm
Where are the answers to the questions above about sweating double-paned vinyl windows?
Ben Erickson Says:October 26th, 2009 at 11:31 am
Hi Kim,
The section under each article on our website is reserved for comments from visitors. While we can’t respond to the thousands of comments and questions we received, we do read every one. There are several more articles on double pane windows on our website that might help. Try clicking on the ones in the “Related Articles” section to the left of the article above, or use the search box on our site to find them.
November 1st, 2009 at 5:00 pm
my ceiling sweat in the winter time and leave mold and a wipe it down what cause this and how can I fix the problem.
November 5th, 2009 at 11:46 am
our office is located in Tampa Fl. We have offices along the front of our building with large windows at each office. We have noticed that the wall below the windows are getting saturated. I can only guess that the windows are sweating at times really bad. lately we have noticed that the mats in each of our offices are molding underneath. our ac system shuts down at night and turns on early in the morning. Do you think that this fluctuation of temp could be causing this problem?
November 27th, 2009 at 10:29 pm
We built a brand new house less than three years ago and the back side of the house, the windows sweat really, really bad.
Can you help us with what to do. Our house is so very energy efficient that our power bill (total electric) with gas logs only that we only burn in extreme cold, never exceeds around $ 150.00 per month. Heat pump is under the house and is 13 sears. Windows are double pane insulated windows. House is total brick to the top of the house and the house is around 2,500 square feet. My wife and I are the only occupants besides our grandson who my wife keeps Mondays thru Thursdays (2 yrs old). We have asked everyone but nobody seemes to be able to help us.
Thanks for your advice!!
Keith Word
Ben Erickson Says:November 30th, 2009 at 11:25 am
Hi Keith,
If the gas logs aren’t vented, that could be part of your problem, since gas generates a lot of moisture when burned. Try the other solutions listed above, such as installing and using fans vented to the outside in the bathroom when showering, and see if that helps.
January 4th, 2010 at 1:43 pm
Hi
We installed several windows in our home and they are sweating. They are double pane hurd windows. Our moisture is only 14%. What else can cause sweating? Can the seals cause it?
Richard Spanton Jr
March 1st, 2010 at 10:12 am
SWEATING WINDOW PROBLEM SOLVED!!!!!!!!!!!!!!!!
YAHOOOOOOOOOOOOOOOOOOOOO
I too would get excessive window sweating on ALL windows in my house.
When I built my house I failed to properly apply the house wrap and tape around the windows and all seams. This was allowing cold air to flow around the perimeter of the window within the rough opening. The lose fiberglass insulation I inserted between the window and the Rough opening had little affect. The window would easily get much colder than the inside temperature which would encourage sweating.
Finally I contacted Ken of Ken Spears Construction of DeKalb County Illinois.
He suggested the following.
-Remove the window trim from around the window.
-Remove all of the lose fiberglass insulation between the rough opening and the window and any house-wrap paper which might be in the space.
-Spray Window ”Insulation Foam Sealant between for Windows & Doors” between the window and the rough opening.
-Replace the window trim.
PROBLEM SOLVED!!!!!!!!!!!!!!!!!!!
June 29th, 2010 at 8:13 am
I live in TN. Recently “conditioned my crawlspace” to include: Installing 6 mil vapor barrier on entire ground surface; sealed all vents; installed E-Z Breathe ventilation system to reduce humidity. NOW, I have begun having a problem with my windows sweating on the exterior.
What can I do to eliminate the window condensation?
Thanks,
Mike
Ben Erickson Says:June 29th, 2010 at 9:09 am
Hi Mike,
I would check the humidity in your home with a hygrometer to see if you might have gotten the humidity too low. It should be somewhere between 30-50 percent. Other options include cutting back on the AC, installing insulated glass windows or storm windows. Good luck with your project!
November 6th, 2010 at 8:59 am
We have double pane windows throughout our home, but they still sweat on the inside bad in the winter. What can we do ourselves to fix the problem?
November 23rd, 2010 at 2:00 pm
Hi Mike
Of course the question come up as winter is here in the NW.
We have double pane aluminin window on one side of the house and these are the ones that sweat on the inside. Our
old wooden ones with the storm windows do not. We only have the problem when it get cold. Is there anything that can be placed over the metal to keep this from happening?
Regards
Joann
November 29th, 2010 at 6:45 pm
Is there a spray or gel that can be applied to windows in the winter to prevent excessive sweating?????
Ben Erickson Says:November 30th, 2010 at 8:20 am
Hi David,
I don’t know of a surface coating that can be applied to windows to prevent sweating.
Ben Erickson Says:November 30th, 2010 at 9:11 am
Hi Joann,
Metal is a much better conductor of heat and cold than vinyl or wood, which is why your metal frame windows are the ones that are having problems with condensation. I don’t know of anything that you could put over the frames to help.
December 14th, 2010 at 4:27 pm
Could defogging spray used in swimming goggles to prevent fogging be applied to windows? I’m just wondering after reading these last 3 comments. Our windows are sweating like crazy, wiping every morning is not nice. also having the heater on all the time is just very expensive.
Ben Erickson Says:December 16th, 2010 at 8:35 am
Hi Hulan,
While it might keep your bathroom mirror from fogging after a shower, I don’t think a defogging spray would help reduce condensation on windows. The suggestions in the article above are about all I know to do about it.
December 29th, 2010 at 10:52 am
I’m with Kim on 10/24/09. Where are the answers about double pane argon filled, best that you can buy windows, WHY ARE THEY SWEATING? I get all the RH jazz and my house is well in the limits for moisture. In the time that you spent telling her to look somewhere else you could have answered her and the many other people with the SAME question. Have you heard of copy and paste or do you just not know thw answer? Thousands of dollars for replacement windows (17 windows to be exact)and they are worse than the 1932 single pane windows I replaced. Not kidding. Just an FYI, my windows were installed using the spray foam between the rough openings like Richard Wild (3/1/10).
So how about it are there enough people interested yet to give us an answer? I actually have water dripping off of my window locks.
Ben Erickson Says:January 4th, 2011 at 4:10 pm
Hi Steve,
Condensation on the inside of windows when the temperature outside drops is nothing new. I seasonally had that problem on the rattling old single pane wood windows in my 1850s house, have it now on the tighter single pane wood windows on my 1960s house, and have seen it on double pane windows on newer houses as well. The suggestions we offered in the article above about reducing humidity, providing venting inside the house, and installing insulating windows are all important; but they may not always solve the problem.
The reason is that while insulated windows reduce the transfer of heat and cold through the glass (which reduces condensation), improved weather stripping on the windows (and tighter new house construction in general) lower air infiltration around the window, which reduces the exchange of humid inside air for dryer outside air. In other words, by making a house tighter, insulated windows (and other energy saving measures) can cause an increase in inside humidity. That makes air exchange systems, venting, and humidity reduction even more important in newer homes to prevent window condensation. Keep in mind that a bath or kitchen vent fan has to have outside air available to draw from in order to expel humid inside air.
Personally, I’ve had the worst problems when a cold front moves through, dropping the temperature and humidity rapidly outside while the air inside is still at the prefrontal, high humidity levels. Once the front has passed and the humidity begins to equalize, the condensation usually goes away. In a tighter new home, the adjustment period will be longer.
You can find more information on dealing with window condensation on the JELD-WEN Windows and Doors website in their article on Condensation: Windows and Patio Doors.
November 3rd, 2011 at 10:52 am
Steve,
To have a partial answer to your question, What brand are your windows? Call them for in depth details to see actually how much of the argon gas they use. You’re gonna be disappointed to know most companies use less than and up to 50% of argon gases in there windows and in time, Will leak out. I worked for a Triple pane Krypton gas-filled Company. What’s gonna need to happen for everyone is, check the types of window Frames and spacers used in the panes.
If you have vinyl-type frames and your windows are sweating, One cause is that those vinyl tubings are hollow with no insulation. You wouldn’t really be able to tell unless you broke a corner of it open or call the Company who made them. Having hollow vinyl frames can still produce major heat/cold buildup, which will not only transfer in and out of your home, but to the windows too depending on the type of spacers/glazing strip (between glass and frame) Which leads into another possibility.
Typical windows will have metal spacers between the glass and frame Thus, still transferring tons of cold to the window and any buildup in the frame will most likely be released through the spacer as well. The ways to check what type you have is to look between the panes around the glass/sill and you’ll see either a metal type, vinyl type or Plastic/rubber material (I have faith you can tell the difference between them) OR call the Manufacture. You can seek to install different types but I’m no technician so I can’t help you there.
Goodluck all.
November 16th, 2011 at 8:15 am
i have double pane vinyl windows. they didn’t sweat last winter, in May we got a new heater. I just found out that the idiot who measured and installed it said we could only get an 85% effective one because of the small space in our basement. We had another heater/AC guy come out and look for us and he said that we got a very ineffective heater and could have gotten the 100% effective one and also the installer, gave us a heater that circulate air differently. so now all windows drips water onto the ledge and we also need a chimney liner because the heater is so ineffective it will cause moisture throughtout the house, so GOD willing we have to get another new better heater with our income tax next year. I don’t turn my humidifier on at all, i have to keep changing the towels on the sills because they soak thru and my shades are all wet and the windows started to get mold. Any help or suggestions to get me thru this winter with this awful heater and dripping we windows would be greatly appreciated. thank you
November 18th, 2011 at 2:16 pm
I have triple low e windows,air exchanger system in our new house.We get a large amount of sweating on our windows.I also have the humidifier system because we have hardwood floors.Temperature setting in house is 68-69 and humidifier is on the required percentile for the outside temp.Nothing seems to help this sweating issue on the windows.What’s your thought on this ?
November 29th, 2011 at 2:41 pm
Hi ijut moved ito my apt an it is cold out side and warm in side so our metal frame around our windows are sweating alot, also there is now black mold from where the water sits. What do we do?
December 2nd, 2011 at 8:29 am
Hi can you tell me if i need a humidifier or dehumidifier,the house is an end one and is really cold in the winter.I have been finding mould on my clothes in the wardrobe and they smell.It doesnt smell in the bedroom but as soon as i open the wardrobe it does.Some of my bags that are kept in the wardrobe have mould in them.The sofa has some green mould appearing on it too.
December 14th, 2011 at 1:01 am
Hello only the one wall in my bedroom gets all sweaty and mold starts to grow on the wall and on the selling that is also the wall that the window what can i do to stop this from happening it only happens in the winter the mold that grows is very black i have 3 kids how bad is the black mold for the health if at all please let me know what i can do I have tryed the stop mold sprays the do not work for long
December 26th, 2011 at 9:04 pm
Please help !! I built a 30×30 room ,8 ft walls 12 different walls,it is self supportting ,has a center hole ,colunm about 3 ft long and 2 ft opening . I heat with a unvented fire place ,keep it 58 to 62 inside my osb is wanting to sweat in places ,i have a rock wall thatss has 3 different water falls ,however i dont run it in the winter cause it really made it sweat vey bad ! would a dehumiderfier help ??