01/14/2015
Condensation and Its Causes
Condensation is visible evidence of excessive moisture in the air. It may appear as water, frost, or ice on the surface of windows and doors. 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 windows, doors, or exterior walls, where the air 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 at the warmer temperature. The moisture is dropped from the air, and appears as water on the cooler surfaces. This occurs more frequently during the winter months because of the extreme difference between the inside and outside temperatures. If you wish to avoid condensation during the winter months, maintaining a 25 – 35 percent indoor relative humidity is advisable.
Ventilation is a very effective way to remove excessive moisture from the air, which is why old, poorly insulated single-glazed windows often do not have condensation problems. New homes, which are constructed to meet current insulation and energy conservation requirements, as well as older homes which have new attic and basement insulation, are often so air-tight they present a new problem: excess moisture in the home.
All homes will, on occasion, have temporary condensation, which is the result of one of three occurrences:
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 doors and windows. This moisture 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, until the house dries out.
Temperature Changes: Sharp and sudden drops in temperature, especially during the heating season, will create temporary condensation.
If you have a high level of moisture in your home resulting in condensation, it will not likely be corrected simply by installing new windows. Remember that storm windows and storm doors do not cause condensation and, therefore, cannot cure condensation.
