All About Condensation: How to Reduce and Prevent Condensation

Condensation is a mystery to many homeowners, especially in the winter months when it’s most common. We’re here to break down your most pressing condensation concerns, and explore how humidity levels and ventilation factor in.

Surface Condensation

Homeowners have varying preferences for humidity levels inside the home during the cold months of the year and depending on those humidity levels, surface condensation can be expected.

For households with high indoor humidity levels, expect surface condensation. Be mindful that the presence of window condensation might signal that humidity levels are too high inside.

Examples of surface condensation include frost on door handles and hinges, doors that become frozen shut, water or ice on windows, damp spots or mildew on walls and ceiling, damp spots or mildew on closet walls, moisture on light fixtures, moisture on water closets, and moisture on cold water pipes, walls, and floors.

Wind Chill Temperature

Wind chill temperature and outdoor temperature should be considered collectively when it comes to preventing window condensation. However, traditional temperature metrics typically don’t include the wind chill factor.

The table above will help break down outside air temperatures, including wind chill, and healthy ranges of indoor relative humidity. Factoring in the wind chill can determine a more accurate recommendation of humidity levels inside the house. For example, the level of relative humidity should be reduced significantly when low wind chill temperatures are mixed with low temperatures.

Factors that Cause Condensation and Can Impact Window Performance

Air Circulation

If it’s cold outside and warm inside but windows are located in an area with poor warm air circulation, the indoor glass temperature will be colder than other areas of the home. This is problematic in that window condensation will form at humidity levels practical for the rest of the house but not at the level needed.


Drapes can restrict warm air flow, which can increase the risk of window condensation. The figures in Table 1 (above) are based on natural circulation of warm air flow without the use of heavy drapes or venetian blinds.

Rooms with Differing Humidity Levels

Different rooms will have varying humidity levels based on the activities performed in each room. For example, the kitchen and bathroom usually have higher humidity levels because of daily events like cooking and showering. Window condensation is much more likely in these rooms.

Window Orientation

Where windows are placed can have an impact on condensation. Windows that are exposed to prevailing winds will be colder than other windows in the house, which will cause condensation at humidity levels more appropriate for the windows that are not exposed to wind.


Depending on external factors outside of the house, certain windows are more exposed and in turn, more vulnerable to direct wind. Other windows might have windbreaks like landscaping, buildings and other large peripheral objects.

Reduce Condensation by Controlling Humidity

A major component in reducing condensation is to reduce humidity levels inside the home. The most effective way to reduce built-up moisture is to increase ventilation. Circulating the dry, cold air outdoors with the warm, humid air indoors will reduce moisture levels.

To control humidity and increase ventilation, try the following:

Keep windows and doors open for short periods of time to let moisture leave the house, turn on the kitchen fan when cooking and vent the fan directly outdoors, keep bathroom doors shut and turn on exhaust fan when showering.

Vent clothes dryers to the outdoors, hang up wet clothes outside instead of indoors to eliminate moisture, turn off any humidifying device, and occasionally open the damper to the fireplace. Leave bedroom and bathroom doors open, and don’t block hot or cold air registers with furniture or appliances.

Maintain room temperature of 50 degrees Fahrenheit (10 degrees Celsius) even when unoccupied, wipe up snow on the floors before it melts, run exhaust fans when mopping floors, and avoid mopping on extremely cold days.

In homes with a fresh air intake into the cold air return duct of the heating system, make sure to keep the intake damper open and unobstructed. Homes without a fresh air intake system should install one.

Leave drapes and blinds open during the daytime, raise them 4” off the ground at night to let air flow against the glass. To avoid extreme temperatures between blinds and window glass and as a result, window glass breakage, leave blinds partially open if the fabric blind is designed to fit from jamb to jamb.


Reflect Window & Door offers expert glass replacement, repair, and installation services throughout Edmonton and surrounding areas in Alberta. We’re proud to offer a wide range of glass services for both residential homes as well as commercial businesses.

If you’re ready to begin your glass replacement project, or you’d like to learn more about Reflect Window & Door, please get in touch with us today.