When a home has excessive humidity, it manifests itself into condensation on the coldest portion of a wall (usually the window). Very warm air causes more moisture to be retained. When the warm air in your home comes in contact with a cold surface, it is then cooled and moisture is released in the form of condensation.

No, condensation does not indicate a problem with a window. However, replacing drafty windows and doors with more air tight ones will reduce the airflow in your home.  Tighter homes retain more humidity.

Condensation is usually found at the meeting rail and at the bottom of the lower sash on the interior glass. When warm air cools, it falls down across the inside surface of the window while the air temperature is falling. The air contacts the meeting rail, which acts as a dam, slowing the air’s rate of fall and creating an opportunity for trapped water vapor to escape and form on the meeting rail. The air then moves over the edge of the meeting rail and again gains speed until it encounters the lower handle of the sash. The water vapor leaves again and lies at the bottom of the sash.

Humidity must be controlled and air circulation generated to reduce condensation. As it gets colder outside, the humidity level needs to decrease to control condensation.

Increasing ventilation and controlling sources of moisture will reduce humidity. The following steps will aid in the process:

Use exhaust fans in the kitchen, laundry room and bathrooms.
-    Vent gas burners, clothes dryers, etc. to the outdoors
-    Shut off furnace humidifiers and other humidifying devices in your home.
-    Open fireplace dampers to allow an escape route for moisture laden air
-    Open the windows every day and allow fresh air into your home.

Remember, better air circulation will help reduce condensation. Raising blinds and shades daily will increase air circulation.