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Condensation on Windows

Submitted by Lorene Bartos, UNL Extension Educator

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Does moisture appear on your windows this time of year? Moisture condensation on windows is caused by excess humidity or water. Condensation on windows is caused because the air temperature is cool on one side and warm on the other. The condensation problem may seem to occur more often today than in the past because of the energy efficient measures being taken when building new homes. In the past, in older homes the techniques used to seal a home and weather-stripping and insulation allowed the home to breathe.

Daily tasks in the home adding several pints of moisture to the humidity level include:

  • taking showers and baths
  • cooking
  • using the dishwasher, washing machine, clothes dryer, etc.
  • running the humidifier
  • crawl spaces not insulated properly

If this problem occurs in your home there are some steps to take to help elevate the problem. To decrease the humidity level in the home:

* Measure the humidity level in your home using a hygrometer. The relative humidity in a home should be between 30 and 50 percent (30 to 40% is best).

* Run exhaust fans when showering or cooking.

* Check your humidifier to make sure it is working correctly or do not run it.

* Vent the attic and crawl spaces.

* Vent all appliances outside.

* Cover dirt crawl spaces with a moisture barrier.

* Store extra firewood outside.

* Leaving the window open a crack will also help with ventilation and reduce condensation.

If condensation does occur on windows, dry the area to keep it from getting mildew or moldy. If hard surfaces become moldy clean first with a dish washing detergent (not dish washer detergent) and then treat with a bleach solution of 3/4 to 1 cup of bleach to gallon of water. Mold will only occur when there is excess moisture.

Take time to check your window areas during these cold spells and take steps to reduce the humidity in your home.



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(This resource was updated December 2008 and appeared in the Lincoln Journal Star Newspaper Sunday edition. For information on reproducing this article or using any photographs or graphics, read the Terms of Use statement)

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