What Can Be Done About Condensation Between Window Panes?

Causes of Moisture Development

• Double paned windows, also called thermal panes or Insulated Glass Units, allow moisture penetration over time due to the stresses placed upon the windows during transport, installation and overall building frame settling in the post-construction period. Windows with a southern exposure are also prone to heat from the sun. The warmth excites the air molecules between the panes and puts pressure on the window's seal. Where the seal is compromised, moisture-laden air makes its way into the space between the panes and makes contact with colder outside panes.

Preventative Measures

• Manufacturers increase the condensation resistance of their windows in several ways. Some load the thermal pane spacer bar at the bottom of the window with a drying agent or desiccant. This material absorbs excess moisture for a period from several months to several years depending on the location of the window and the amount of humidity to which the window is exposed. Other measures include inert gas placement between glazings, low-emission coatings to warm the glass and insulating spacers to reduce heat flow.

Post Installation Safeguards

• Window glass may also warm during the winter by freely admitting sunlight through the window panes. Leave your drapes open on sunny winter days to allow the sunlight to shine through. Carefully select and regularly trim trees and shrubs so that they don't shade or obstruct solar energy. Don't allow interior window curtains, valances and blinds to inhibit the movement of air around window surfaces. Air circulation will reduce condensation occurrence.

Indoor Humidity Levels

• Take steps to prevent excess humidity in the home. An increase in ventilation will decrease condensation events. During the winter months, disconnect all humidifiers. Vent clothes dryers to the outside and keep the vents clear of snow and ice build-up. Equip high humidity areas such as bathrooms and kitchens with fans to carry moisture outside. Turn on your mechanical ventilation system or install a heat recovery ventilator system to enhance the circulation of air in your home.