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With the recent drop in temperatures in Edmonton, our staff at Classic Exteriors have been getting quite a few calls from our customers, asking why their windows are frosted up. Let us explain about the cause and what you can do to reduce window condensation at your home.

What Causes Window Condensation?

There are many factors that contribute to the frosting or fogging up of windows. Here is a basic summary of what happens:

When warm moist air inside of your home touches the cold surface of the window, the moisture sticks to the window. The temperature of that window then drops below the dew point and as a result, the moisture freezes to the window. Think of an ice cold can of pop on the hottest summer day. As soon as you put it on the table it starts to sweat and creates those water rings under it. The frost on your windows is the same basic principle.

In Alberta, a lot of times frost is a fact of life, and the moisture and water in your house may cause damage over time. If you do have frost formed on your windows, place a towel on the window sill when the weather is set to warm up so it catches the moisture as the frost melts off the glass.

How to Prevent Window Condensation?

To prevent the frost on the windows here are some tips and tricks that we recommend:

1. Adjust Humidity Level

If you have a dehumidifier, you can control the humidity level in your home based on the guideline below:

Outside Air Temperature     MAXIMUM Interior Humidity

0C to -5C                           40%

-5C to -17C                         30%

-17C to -28C                        15%

2. Proper Ventilation in Your Home

Modern homes and newly renovated homes are extremely well-sealed, which means all of the moisture you create in your day-to-day activities, such as taking showers, boiling water, and making coffee or tea, stays within your home and condenses on your cold windows. So, moving the air in your home is crucial so that the air is not standing still and will disallow the moisture to sit against the windows. Also, venting the moisture filled air outside will help control your moisture levels. Your bathroom and kitchen exhaust fans should be your best friends in cold winter months.

3. Keep Blinds Open

Avoid standing air by keeping blinds open or cracked just a bit at the bottom. When moist air gets trapped behind your curtains, it is certain to condense against the cold glass causing your window to frost.

4. Limit Your Moisture Sources

Try to limit the amount of water you boil, limit the showers to one a day, or if possible, avoid doing laundry on the coldest days. If your furnace has built-in humidifier, we suggest you turn it off. In addition, limit the amount of plants, pets and aquariums you have in your home.

5. Raise the Temperature Inside Your Home

Warmer air holds more moisture in it so when it touches the cooler windows the moisture just might stick in the air rather than condensing against the window.

6. Window Upgrades

Lastly, if you have single paned windows, you can consider upgrading to double or triple paned windows. This will not eliminate the problem, but the air gap in between the panes of glass will certainly slow down the cooling process and lessen the amount of frost.

If you are insulating your home, the moisture problem may become a new problem that you never had before. Your home likely had natural drafts; when we insulate and seal the home, we remove the moisture escape points and thus increase the humidity in your home which even with double or triple paned windows can still get frosty. Therefore, the tips to avoid or lessen window condensation mentioned are vital to newly insulated homes.

As homeowners, while you enjoy a comfortable home built by modern building practices and using energy-efficient windows to lower your energy bills, it is also important to understand how your homes react to the moisture and cool air, and take preventive measures to maintain your home in the best condition.

If you need further information about window condensation, please check out this article which explains window condensation including diagrams to help you understand how your home reacts to certain conditions.

Want to talk to our home renovation experts about window condensation or energy-efficient windows? Feel free to contact Classic Exteriors directly and we are happy to help!


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