7 Ways to Reduce Window Condensation and Indoor Moisture

Your windows serve a number of practical purposes in your home, including the obvious sources of natural light infusion and the all-important wintertime function of heat retention.  But, also in the wintertime, the difference between the cold air outside, and the cosy comfort inside can result in another issue – moisture in the form of condensation.

So what are the sources of condensation, what’s to be done about it? Here’s window replacement expert Roone Unger of exovations.com to tackle these common questions …


Why are my new replacement windows getting condensation on the inside of the glass?

This is a very common question with homeowners not just after having windows replaced. Sometimes a homeowner may be considering replacing their windows in an effort to cure this problem. To answer these questions lets determine what causes window condensation.

Condensation is visible evidence of moisture in the air. It may appear as water, frost, or ice on the surface of windows and doors. This occurs more frequently during the winter months because of the extreme differences between the inside and outside air temperatures. The warmer the air, the more water the air can hold. This  means that the air in the center of any given room will hold more water than the air adjacent to the window or door walls, since this area is always cooler. When the warm, moisture-laden air moves toward the cooler window or door wall, it becomes cooler and cannot hold the moisture it held when it was warmer and is dropped. This effect appears as water on the glass and frames of windows and doors.

Windows do not cause condensation, they just happen to be the place where moisture is most visible. Condensation is a sign of excess moisture in the home.

Temporary sources of condensation

  • New Construction or Remodeling: Building materials contain a great deal of moisture. As soon as the heat is turned on, this moisture will flow out into the air and settle on door and window glass. This will usually disappear following the first heating season.
  • Humid Summers: During humid summers, houses absorb moisture. This will be apparent during the first few weeks of heating and then should dry out.
  • Temperature Change: Sharp, quick, and sudden drops in temperature especially during the heating season will create temporary condensation problems.

More permanent sources of condensation

  • Poor Ventilation: Insufficient attic ventilation and/or soffit ventilation is trap moisture in the home. Having sufficient soffit vents to allow air flow through the attic ventilation will allow moisture and humidity to escape
  • Excessive Humidity: Excessive humidity may be the result of poor ventilation but can also be a result of an imbalanced heating and air system or a need to add additional ventilation such as bathroom or kitchen exhaust vents.

Controlled ventilation and elimination of excessive indoor moisture can keep humidity within bounds.

Here are 7 suggestions to help reduce indoor moisture

1) Turn off or set back furnace humidifiers until sweating (condensation) stops. Remove pots of water on radiators or kerosene heaters.
2) Use exhaust fans or open windows slightly in kitchen, bathroom and laundry room during periods of high moisture production such as cooking, taking showers, washing and drying clothes. Clothes driers must be vented outside. Do not hang clothes to dry indoors.
3) Keep the basement as dry as possible by waterproofing floors and walls.
4) Make sure attic vents are unobstructed.
5) Place all house plants in one sunny room where the door can be kept shut and avoid over watering.
6) Opening windows slightly for a brief period of time will allow humid air to escape and drier air to enter.
7) Use a dehumidifier, properly sized, to reduce the humidity in the house.

Excessive indoor humidity and moisture are not the result of your new windows. You should use the amount and severity of window condensation as a sign that moisture damage may be taking place inside the walls or ceiling cavities of your home. This can lead to rotting wood, deteriorating insulation, and blistering exterior paint.


Thanks, Roone!

Roone Unger is co-owner of Exovations of Atlanta, a home exterior remodeling company focused on conducting business the way consumers want and expect.

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