How to Cure Sweating Windows
Ask Danny, Doors and Windows, Heating and Cooling by Danny Lipford
I live in Greenwood, Arkansas. When the temp gets around 35 or below, the 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. Would a dehumidifier help? I read that too much humidity would cause it. I even noticed it was sweating on the metal strip at the bottom of the front door last night. 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 a cold window or metal threshold, 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:
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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.
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Vent gas fireplaces, or limit their use, and don’t use older unvented gas space heaters.
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Cut down on cooking that produces excess steam.
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Lower your thermostat to 66-68 degrees.
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Be sure your clothes dryer is vented properly to the outside.
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Seal up any cracks around windows and doors.
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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.
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If you are still having problems, consider installing a dehumidifier.
12 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?