Why your windows stream with condensation — and how to manage it
Morning condensation is cold glass meeting warm, moist air. Here’s what causes it, and the practical steps — windows included — that help keep it under control.
If you’re wiping down the windows most mornings, you’re not alone. Condensation is one of the most common complaints we hear from Canterbury and Wellington homeowners — and it’s usually a sign your windows are doing a poor job of holding heat.
Why it happens
The air inside your home carries moisture — from cooking, showers, drying washing and simply breathing. When that warm, moist air meets a cold surface, the moisture condenses into water. The coldest surface in most rooms is the window, which is why the glass and sills get wet first.
The colder the glass and frame, the worse it gets. Single-glazed windows and aluminium frames sit cold, so they stream the most.
How better windows help
Double glazing keeps the inside pane warmer, so moisture is far less likely to condense on it. Warm-edge spacers reduce the cold line around the edge of the glass where condensation usually starts. And insulating uPVC frames don’t sit as cold as aluminium, so they sweat less.
It’s important to be honest here: better windows help manage condensation, they don’t eliminate it. Ventilation and heating matter too.
The full picture
- Warmer glass and frames — the job good windows do.
- Ventilation — move moist air out, especially after showers and cooking.
- Steady heating — keeps surfaces above the temperature where condensation forms.
If your windows are the weak point, replacing or retrofitting to double-glazed uPVC is the single biggest step you can take toward a drier home.