Say goodbye to window condensation!

Say goodbye to window condensation!

What to do when you notice condensation on your windows? Here are some tips to wipe it out.

What causes condensation on windows?

Windows fog up when warm, moisture-laden air comes into contact with a cold glass surface.

Water vapour then turns into liquid or ice on windowpanes.

The risk of condensation inevitably increases as the temperature decreases outside. So don’t be surprised if there is more fog on your windows in the winter than in the summer.

That infamous humidity level

Several factors can affect humidity inside a home.

Air drying your clothes, taking a shower, boiling water while cooking, washing the dishes and doing laundry are all activities that can increase the humidity level inside your home.

Construction defects (a damp basement is often the culprit) or even a faulty ventilation or air exchange system may also be to blame.

The right mix of humidity and outdoor temperature

Use a hygrometer to measure the humidity levels in your home.

You will then be able make adjustments based on the humidity level, outdoor temperature and recommended indoor temperature settings.

Outdoor temperature

Indoor humidity controlled with an indoor temperature of 21 oC and below

-7 oC


-12 oC


-18 oC


-24 oC


-29 oC

20 %

High-performance windows and doors

Windows and doors are the first to feel the effects of cold weather outside. All the more reason to make sure they are well insulated.

Your seal of quality against condensation is the ENERGYSTAR certification.

There are several models on the market, but triple-glazed windows are the best line of defence against condensation.

Thermal windows (or double-glazed) are also effective, especially those with plastic film insulation stretched between the two panes of glass.

Single-paned windows are not recommended to withstand Canada’s harsh winters. This type of window collects more condensation. Furthermore, its acoustic performance, i.e., its ability to block noise, leaves much to be desired.

If your windows do not need to be replaced

Remove window screens and store them during the winter.

Always keep curtains and blinds open during the day so the sun can do its job of warming window surfaces.

Let the air flow!

Open windows to let in some fresh air, weather permitting. This will reduce humidity inside.

Leave all the doors open too and let fresh air flow everywhere.

Check to make sure that bathroom and kitchen fans are working properly and are effectively removing moisture. Verify that exterior vents are not blocked.

Consider installing an air exchange system if your home does not already have one.

Lower the temperature, but…

Turn down the heat when you go out, but not too much!

If the temperature is too cold, window surfaces will get cool and this could cause them to fog up.

If you have poorly insulated areas in the home, it’s time to caulk them. This will prevent air drafts that lead to condensation.