Condensation, Frost & Ice on Windows

Condensation may appear on your window at different times depending on the humidity (the amount of water vapour in the air) and the temperature inside your home and at the surface of the window. Condensation usually appears on windows before any other surface because windows contain the least amount of insulation, are part of your homeʼs exterior wall, and react quickly to temperature changes inside and outside.

You can control condensation by reducing the amount of moisture (or humidity) inside your home when outside temperatures drop and the window surface becomes cool.

Many everyday activities add moisture to the air in your home, including cooking, showering and doing the laundry. Other household items that add moisture to the air in your home include plants, fish tanks and humidifiers.

Reducing Condensation

There are many ways to reduce condensation and control the moisture content in your home. The following tips can help you reduce the amount of moisture in your home and condensation on your windows:

  • Vent moist air outside and bring fresh dry air inside (i.e., bathroom fans and kitchen range hoods) to remove high concentrations of moisture
  • Run your home’s ventilation system continuously or as part of a timed circulation mode
    Run the furnace fan continuously during periods of extreme cold to evenly distribute heat throughout your home
  • Keep window drapes or blinds open or partially open during cold weather (especially at night) so that indoor air can move along the window to decrease the amount of condensation that collects on the window (closed drapes and blinds restrict air flow near windows).
  • Keep air and heating vents located near windows uncovered. The movement of warm air along the window surface reduces the potential for condensation to build up.
  • Make sure air and heating vents are deflecting the movement of air towards the window by adjusting the direction of the vent.