top of page

Why Is There Frost on the Inside of My Windows?

frost inside home window panes

Although frosty windows make for a beautiful winter image, they can actually harm your home. Frost on the inside of your windows can signal a problem with your home’s humidity, airflow and windows. Here’s a look at what causes window frost, why it’s a problem and what you can do about it.

Causes Of Window Frost

Frost is caused by condensation, which happens when warm air touches a cold surface. Warm air holds more moisture than cold air. Therefore, when it meets a cool surface — like a window during winter — the air quickly cools, turning the water vapour into droplets that freeze on the windows.

Why Frost Is a Problem

Ice build-up on your windows and sills can cause aesthetic and structural problems. When the frost melts, the water can sit on the window frame and discolour the finish, warp and rot the wood, crack the paint and cause mould and mildew growth. The water can also trickle down into the walls, rotting your drywall, studs and insulation, leading to the growth of harmful black mould.

Preventing Window Frost

Fortunately, you can take several steps to prevent window frost, including:

  • Controlling humidity. Ensure your furnace humidifier is set correctly. If needed, place a portable dehumidifier in problem rooms.

  • Increasing airflow. Install ventilator fans in all bathrooms, the kitchen and the laundry room. Run them every time you cook, shower or do laundry, and ensure the air is vented outside and not to the attic. Switch your ceiling fans to winter mode to circulate warm air trapped near the ceiling. Moreover, consider installing a heat recovery ventilator (HRV) to bring fresh air from outside without opening windows and doors.

  • Replacing your windows. Single-pane windows are much more vulnerable to window frost than double- or triple-glazed windows. Older, drafty windows also encourage frost. Investing in new weatherstrip and using caulk to fill cracks and gaps may help. However, in most cases, it’s worthwhile to invest in energy-efficient double- or triple-glazed windows. Multi-glazed windows with argon gas and Low-E coatings can further increase your home’s efficiency and eliminate condensation.

Window Replacement and Installation in Northwest Canada

At All-West Glass, we carry a wide selection of high-performance, double- and triple-glazed residential windows installed by our team of professionally trained, insured and bonded glaziers. Contact us today in Edmonton, Whitehorse, Yellowknife or one of our 18 locations to get your window replacement started.

bottom of page