What is condensation?
Condensation is fog that suddenly appears in the cold weather on the glass of windows and sliding glass doors. It can block out the view, drip on the floor, and freeze on glass. It’s annoying! It’s natural to blame the windows, but you shouldn’t.
What causes window condensation?
Window condensation is the result of excess humidity in your home. The glass only provides a cold surface on which the humidity can visibly condense. The fog on your windows is a form of condensation; so is the water that forms on glass of iced tea in the summer, and on the bathroom mirrors and walls after a hot shower. Condensation usually occurs first on the windows because glass surfaces have the lowest temperature of any of the interior surfaces in the house. When the warm, moist air comes into contact with cooler surfaces, the moisture condenses.
This is important because your foggy windows and sliding glass doors are trying to tell you to reduce indoor humidity before it causes hidden, costly problems elsewhere in your home – problems like peeling paint, rotting wood, buckling floors, insulation deterioration, mildew, even moisture spots in ceilings and walls. Foggy windows and sliding glass doors are the indicators, the warning signs, that humidity could be damaging your home.
How can my home have indoor humidity?
Humidity is water vapor or moisture in the air. All air contains a certain amount of moisture, even indoors.
Where does the moisture come from?
Many things generate indoor moisture like humidifiers, heating systems, and even plants. Cooking three meals a day adds four to five pints of water in the air and each shower contributes half a pint. In fact, every activity that uses water (like dishwashing, mopping floors, doing laundry, etc.) adds moisture to the air. The more water vapor in the air, the higher indoor humidity and high indoor humidity means condensation.
How much indoor humidity is too much?
The householder can use the windows and sliding glass doors as a guide to the proper level of humidity within the house. If objectionable condensation occurs on the inside surface of the windows, the humidity level is too high. To avoid excess condensation, the following winter humidity is recommended in the house.
Outside-Inside Relative Temperature Humidity:
-20° F: 15-20%