Frequently Asked Questions
What is this water on my windows?
Water or frost on windows is condensation. Condensation is formed when warm moist air comes in contact with cooler dry air. An example of this is when a bathroom mirror “steams up” after a hot shower. Just like that mirror, the inside or outside of your window can sweat or fog because of temperature differentials.
Are my windows to blame?
Faulty windows do not cause condensation. Glass is usually the first place you notice condensation because glass surfaces have the lowest temperature of any surface in a house. Modern windows and doors generally have a lower air-infiltration rate than the older products. Also, when new framing is installed, with insulation and full caulking around the perimeter, the house is tighter than in the past has a lower rate of air-change. Consequently, condensation problems that were not apparent before may surface.
Then what's the cause?
The moisture in the air causes condensation. The reason you may observe more condensation in your home is because of modern energy-efficient homebuilding techniques and products.
The insulation and construction materials used today are designed to keep cold air outside. This is especially true of new windows. While energy-efficient designs and weather-stripping keep cold air outside, they also keep warm moist air inside. Older window designs were less efficient and consequently allowed moisture to escape.
If you didn’t have as much condensation before replacing your old windows, it’s probably because they were drafty. Good windows and insulation all create barriers to the air exchange of a home. When combined with the additional water vapor (moisture) from showers, cooking, or from clothes dryers not vented to the outside, the result is excess moisture and a high relative indoor humidity level.
The following may cause condensation to form on a window:
Air Circulation - a window may be in an area in which there is poor circulation of warm air. This means that the temperature of the inside glass surface is colder than in other parts of the home and this may cause condensation to form at humidity levels which are practical for the rest of the home.
Drapes - by drawing heavy drapes over a window, or patio door, the possibility of condensation can be increased because the flow of warm air is restricted.
Interior insulating devices - insulating blinds, shutters, or similar devices, applied to the interior of windows, can contribute to condensation problems when moist indoor air is trapped between the device and the window.
Varying Humidity Levels - remember that the humidity in some rooms, kitchens and bathrooms in particular, can be higher than in other areas of the home, thus encouraging condensation to form on the windows in these rooms.
Orientation - if windows are exposed to prevailing winds, then they will be slightly colder than the other windows in the home and may cause condensation to form at humidity levels which are practical for the rest of the home.
Exposure - some windows in the home may be protected by other buildings, trees, etc, which form a windbreak, while other are totally exposed to the wind and, therefore, colder.
How can condensation be reduced?
The key lies in controlling the humidity inside your home. First, let’s understand where the moisture comes from. During the hot humid summer, your house absorbs moisture. The same principle applies to a newly constructed or remodeled home, due to the abundance of moisture from the building materials used in construction.
During the beginning of the winter when you start to heat your home, condensation occurs. After a few weeks, your home will begin to dry out and you’ll see less condensation. Opening a window briefly is a quick temporary solution. The drier cold air will enter the room while the moist air is allowed to escape.
Other solutions that may reduce condensation include:
Cracking open a window or door daily to air out your house.
Opening a window or running exhaust fans longer in the kitchen, bathroom and laundry room.
Opening drapes and blinds, allowing air to circulate against windows.
Turning off any humidifying devices in your home.
Installing and using a dehumidifier.
When should I be concerned?
Window condensation should only occur when there are extreme temperature differences between indoor and outdoor spaces. In addition, there should only be a fairly small amount of water on the glass. Condensation will be seen on the inside of a window during winter months, and will present itself on the outside of a window during summer months.
If you find condensation between the two layers of glass in an insulated window, the airtight seal has probably been broken and the glass will need to be replaced.
If there is too much moisture inside the home, you will see evidence during both the cold and warm seasons. Moisture spots on the ceiling or walls, peeling paint, rotting wood, delaminating plywood, moisture on exterior walls, and fungus, mold or mildew growth are signs of a more serious moisture problem. Should you experience these symptoms, an expert heating & cooling contractor should be contacted in order to solve the problem.