Condensation Causes and Cures

Condensation forms when warm, moist air touches a surface that is colder than the dew point of the warm air. As that air becomes colder and its temperature drops below its dew point, it must release excess moisture to reach its new, lower dew point. It releases moisture in the form of water, which appears on the colder surface.

A common example of moisture condensation is when a glass of ice water “sweats” when you bring it outside in the summer. When the warm, moist air touches the cold glass, the temperature of the air drops below its dew point, forcing the air to release moisture in the form of water on the sides of the glass. There are many things in our homes that put moisture into the air. Normal breathing and perspiration add 3 pints of water to the air every day for each person in your home. In fact, every activity that uses water adds more moisture to the air including cooking, taking showers, dishwashing, and doing laundry.

What If Condensation Appears on Your New Harvey Windows?

Your new Harvey windows are designed to prevent air infiltration into and out of your home. Your old, drafty windows allowed the moisture in your home to escape (along with your heat)! Your new Harvey windows are tight and do not allow the moisture in your home to escape. You need to control the humidity in your home.

Controlling Indoor Humidity

Homes are now made tighter than ever. They are well insulated and no longer “breathe” on their own. Steps must be taken to ventilate the house, allowing moisture and humidity to escape. With proper ventilation, you can eliminate condensation before it causes any major damage to your home.

Steps to control the humidity in your home include:

  • Venting gas burners and clothes dryers to the outside
  • Installing exhaust fans in the kitchen, bathrooms, and laundry rooms
  • Controlling or covering other sources of humidity (radiator water pans, fish tanks, large numbers of plants, etc.)
  • Installing a dehumidifier
  • Opening fireplace damper
  • Ventilating the crawl space or basement: Install foundation vents or leave a basement window cracked in the fall or early winter to ventilate your basement or crawlspace
  • Ventilating the attic: Because of vapor pressure, the moist warm air from your home can go right through your ceiling into your attic. If your attic is not ventilated, the humid air will condense on the cold underside of your roof. This condensation can start to rot the roof boards, cause ice dams, or drip down onto the ceiling below and damage your plaster, paint, and attic insulation.
Condensation In Your Home - A Warning Sign

Condensation can occur wherever warm, moist air comes in contact with a colder surface, which is why it usually happens during the winter. During winter, the air in your house is much warmer than the air outside.

Condensation usually is first noticed on your windows because they are the most visible areas of your house. Condensation on your windows means that the air in your house has too much moisture in it. Your indoor humidity is too high. While you notice condensation first on your windows, it could mean that your excessive indoor humidity is causing damage elsewhere in places you can’t see, such as your walls, ceilings, floors, and your attic roof. Excessive indoor humidity can cause blistering and peeling paint, warping and rotting wood, as well as the formation of mildew.

Condensation vs. Seal Failure

It’s very important to note that condensation is not an indicator of a seal failure in your windows. If there is fogging, hazing, or moisture occurring between the insulated glass panes that cannot be touched or wiped away, that could be an indication of a failed seal. If this happens, please contact our field service department and we will promptly respond.

Temporary Condensation

Wood, plaster, cement, and other building materials used in new construction and remodeling produce a great deal of moisture. A new home or addition will have excessive moisture from the new foundation. Concrete does not dry completely for up to one year. Rapid drops in temperature can also create temporary condensation problems during the heating season.

In order to provide you with accurate information on condensation, the following sources were used.

  • Moisture Condensation; published by the University of Illinois at Urbana-Champaign
  • The Condensation Problem – Here are the Causes and Cures; by H.B. Dickens, published by the Canadian National Research Council
  • Fundamentals of Residential Attic Ventilation; published by H C Products, Princeville, Illinois
  • Moisture Condensation in Well-Insulated Homes; published by Dow Chemical Co., Pittsburgh, Pennsylvania
  • Condensation on Window

    Condensation Causes and Cures