All air contains a certain amount of moisture. Indoor humidity is generated by many household activities including cooking, heating system, humidifiers, showers and moping floors. Every activity that involves water adds to the humidity level in your home. 

Climates are also a factor in condensation. In homes where the January temperature drops below 2 C there is greater temperature differences affecting the glass in your home, thus more likely for condensation to occur. It is typical to experience a bit more condensation to occur at the start of each heating (winter) season, compared to the rest of the season.

With homes becoming more energy efficient through high-performance insulation, moisture-barrier materials and airtight construction it is another contributor to household condensation. As homes are more tightly sealed keeping the cold out it also keeps the moisture in creating higher humidity levels and more condensation.


  • Proper air circulation near windows. The reason heat sources (i.e. central heating vents, or electric baseboards) are located beneath windows is that it allows air flow across the glass surface with helps to keep it warmer. Nearby furniture, closed drapes and blinds can block air flow and cause cool air to accumulate around the window thus leading to condensation on the glass.
  • Use a dehumidifier to remove excess moisture in a basement


Condensation or "sweating" on windows is caused by excess humidity or moisture in the air in a home. When the moisture in the air comes into contact with cooler surfaces, such as a mirror or window, the air condenses into water droplets called condensation. Condensation increases as the weather gets colder and the humidity in the home increases. Condensation can even occur on the outside of windows.

  • Be sure that all sources of ventilation to the outside is in working order. After each humidity producing activity make sure to turn on kitchen, bathroom or laundry room exhaust fans to vent excess moisture.
  • Periodically air out your home. For a few minutes each day open your windows a little bit, thus will allow stale moist air to escape while allowing fresh dry air to enter your home without compromising on your heating.
  • Check humidifier settings. The table shows recommended or comfortable levels for indoor humidity during the window months. a humistat or psychrometer can measure indoor humidity levels.




Relative Humidity

-29 C15%
-23 C20%
-18 C25%
-12 C30%
-7 C35% - 40%