Wake up to frost on the inside of your windows? You’re not alone. In a Winnipeg winter, it’s one of the most common questions we get. The good news: it’s usually fixable.
What causes it
Warm indoor air holds moisture. When that air touches a cold glass surface, the moisture turns into water droplets. Below freezing, it turns into frost. The colder the glass and the more humid the house, the worse it gets.
Where the condensation is tells you a lot
| Where you see it | What it usually means |
|---|---|
| Inside surface of the glass | Indoor humidity is high, the glass is cold, or both |
| Between the panes | The window’s seal has failed — the unit needs replacing |
| Outside surface | Normal; it’s a sign of a well-insulated window |
Quick fixes to try first
- Lower indoor humidity. Turn down the humidifier, especially on the coldest nights.
- Run exhaust fans. Use bathroom and kitchen fans during and after showers and cooking.
- Let air circulate. Open blinds and curtains during the day and keep vents near windows clear.
- Check your HRV or air exchanger if your home has one, and make sure it’s running and clean.
When it’s the window, not the house
If the fixes above don’t help, the window itself is likely the problem. Older or single-pane windows have very cold inside surfaces, so even normal humidity condenses on them. Fog between panes is a failed seal, and the window has lost much of its insulating value.
Left alone, constant moisture can damage sills, drywall and paint, and lead to mould.
The long-term fix
Modern energy-efficient windows keep the inside glass much warmer, which cuts down on condensation and frost. Arctic Star installs windows that are made in Canada and built for Manitoba winters, backed by a lifetime warranty. We install all winter long, one window at a time.
Tired of frost on the inside of your glass?
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