Homeowner Helpers: Reduce window condensation with these easy tips

Window condensation is a common problem in Ottawa homes in winter. And with the recent change in weather, chances are this is something you’re now seeing in your home.

Just like an ice-filled glass on a hot day will sweat in the heat, a window separating cold winter weather outside from warm air inside (especially in a house that has a lot of humidity) is prone to developing condensation.

There are a few things you can do to minimize that window condensation.


Remove screens to control window condensation

Many of today’s windows — particularly if they’re casement ones — have insect screens on the inside. This is done so that your windows can swing open.

The problem with interior screens in winter is that they can impede the warm air flow from your duct vents. Vents are located under windows specifically so they can direct air flow towards the windows. The warmer the glass is, the less window condensation you’ll get. That means you shouldn’t use deflectors to direct the air flow away from the window into the room instead.

And even if your screens are on the exterior, this study showed that leaving them up in winter can block 30 to 40 per cent of the heat gain you could get from the sun. Besides, snow and ice can accumulate between the screen and window, potentially damaging the frame, sill or screen itself.


Keep it moving

Just as screens can limit air flow around your windows, the same can be said for curtains and blinds. The more you can keep them open, the better the air circulation around the glass.

Similarly, if you have forced air heat, leave the furnace fan on “circulate” so the air keeps moving over the windows even when the heat is not cycling on. Ditto for your ceiling fans; leave them on 24/7 to keep air moving.window condensation

Humidity levels

If these simple steps are not enough, chances are the humidity level in your home is higher than it should be. Older homes were much “leakier” than the ones built or renovated today, which means they could breathe easier to let warm moist air escape and let drier cool air seep in.


New homes will typically include an HRV or heat recovery ventilator to help control humidity levels. If yours doesn’t, here is some guidance, as well as further tips on reducing humidity to control condensation.

Why you need to bother about window condensation

Window condensation is often a symptom of a larger problem and ignoring it can lead to the growth of mould, which has implications for your family’s health. If you’ve already got mould, here are some steps for dealing with it.

Originally published Nov. 21, 2018.


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