Understanding Condensation

Learn What Condensation Is and How You Can Address It In Your Home.

Condensation (water vapor or moisture in the air) is a sign of excess humidity inside the home. Condensation occurs when moist air comes in contact with the colder surface, such as a window or mirror. Although the surface of a window may be the first place you notice condensation forming, the window is not the problem. Windows, in this case, merely provide a visible sign that excess humidity or moisture is present in the house. Warm air holds more moisture than cool air. When that warm, moist air comes in contact with a cooler surface, the moisture suspended in the warm air transfers to the cooler surface as condensation.

Understanding Condensation 101 Video
A screen capture from Atrium Condensation 101 video

Learn more about the causes of condensation on windows in your home, as well as ways to reduce or eliminate it.

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Dealing With Condensation In The Home


What causes moisture inside a home?


Window glass with condensation on it.
Window glass with condensation on it.

Indoor moisture in the air is caused by a variety of factors. Common household activities such as cooking, showering, using the washing machine or dishwasher and other activities that use hot water all add moisture to the air. Newer homes are often more subject to condensation because they are constructed with better weather tight materials than older homes. Weather stripping, improved insulation, vapor barriers and modern construction techniques are designed to reduce air leakage. But at the same time, these materials and techniques can also seal moisture inside the home. In newer, more weather tight homes, it is important to be aware of humidity levels and to provide adequate ventilation to reduce humidity levels.

Lower Condensation In Your Home


  • Turn on indoor ceiling fans
  • Make sure appliances such as clothes dryers vent outside
  • Use the exhaust fan when cooking or showering
  • Refrain from using humidifiers
  • Install a dehumidifier
  • Open windows and doors occasionally to allow interior moisture to escape
Condensation Causes and Cures – ( pdf | 45 KB )

Newer Homes and Condensation


Newer homes are often more subject to condensation because they are constructed with better weather-tight materials than older homes. Weather stripping, improved insulation, vapor barriers and modern construction techniques are designed to reduce air leakage. But at the same time, these materials and techniques can also seal moisture inside the home. In newer, more weather tight homes, simply be aware of humidity levels and provide adequate ventilation to reduce interior moisture.

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Windows 101 Video Series

Enjoy our collection of animated educational videos covering a variety of topics including condensation, window styles, window options, warranties, window/building codes and more.

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