Window Condensation in Your Home

Window condensation can be a common problem, even on new energy efficient windows. It's not the fault of the window, unless its an old single pane window. The main cause is the moisture level is too high in your home - indoor environments should be between 30% and 50% relative humidity. “Relative Humidity” is the amount of water vapor the air contains compared to the maximum amount it could hold at a given temperature. The indoor relative humidity may need to be lower in winter to avoid condensation on your windows. If the temperature of the glass gets below the dew point of the air in your home, the air can no longer hold the water and it condenses on the cold glass.

We have some tips to control condensation:

1. If you have a humidifier, adjust your humidity level as the temperature outside drops below 30°F. These are recommended settings to avoid condensation.
- 35% at 30°F
- 30% at 10°F
- 25% at 0°F
- 20% at -10°F

2. Use the bathroom fan during and for 15 minutes after running hot water or showering. Make sure the fan is working efficiently. A fan timer can be set after leaving the room.

3. Turn on your kitchen exhaust fan when cooking and make sure your fan vents to the outside.

4. Open your blinds to let the warmer air from the room get to the windows. The cold air built up behind a blind holds less moisture and will promote condensation.

5. Turn on ceiling fans - this also gets warmer, drier air to the window surface.

6. Install a whole house ventilation system with an air exchanger and humidity control.

7. If you can not control humidity well enough to eliminate condensation, wipe your windows regularly so window frames and possibly the wall structure below the windows will not rot.