How to Stop Condensation on Windows

Waking up to water running down the inside of your windows is one of the most common — and most fixable — moisture problems in a home. This guide explains why it happens and the practical steps that actually stop it.

General guidance. Persistent condensation that’s causing mould or damage may point to a wider ventilation or building issue worth getting checked.

Why condensation forms on windows

Warm air holds more moisture than cold air. Your indoor air picks up moisture from cooking, showering, drying clothes and simply breathing. When that warm, moist air touches a cold window, it cools, can no longer hold the moisture, and it condenses into droplets on the glass.

That’s why it’s worst:

in winter (cold glass),
in the morning (moisture built up overnight),
in bedrooms, kitchens and bathrooms (where moisture is produced), and
on single glazing or cold frames.

How to stop condensation on windows

1. Ventilate moisture at the source

Use extractor fans when cooking and showering, open windows briefly each day, and keep trickle vents open so humid air can escape rather than settling on cold glass.

2. Reduce the moisture you create

Cover pans when cooking, dry washing outdoors or in a ventilated room, and avoid drying clothes on radiators — a major hidden source of indoor moisture.

3. Keep a steady background warmth

Consistent, gentle heating raises surface temperatures, so moisture is less likely to condense. Short bursts of high heat in an otherwise cold home tend to make condensation worse.

4. Wipe, and improve over time

Wipe morning condensation off glass and sills so it can’t pool and feed mould. Over the longer term, better insulation and glazing reduce the cold surfaces that cause it.

Condensation, mould and damp

Left unmanaged, window condensation keeps sills and frames damp and leads to black mould on frames, sealant and nearby walls. If that’s already happening, see how to get rid of mould on walls and the bigger picture in condensation explained.

If condensation and mould persist despite good habits, the property’s ventilation or fabric may need attention — an independent damp and mould surveyor can advise. Renting? See your rights as a tenant.

Frequently asked questions

Why do I get condensation on the inside of my windows?

Warm indoor air holds moisture; when it touches cold glass it cools and the moisture condenses into water droplets. It's most common in mornings, in winter, and in bedrooms, kitchens and bathrooms where moisture is produced.

How do I stop condensation on windows?

Reduce indoor moisture, ventilate it away (extractor fans, trickle vents, brief window opening), and keep a steady background warmth so surfaces are less cold. Wipe existing condensation so it can't feed mould.

Is condensation on windows a problem?

A little is normal, but persistent condensation keeps sills and frames wet and leads to mould and damage over time. It's also a sign your home has more moisture, or less ventilation, than is ideal.

Does condensation mean I have damp?

Condensation is itself a form of damp — the most common one in homes. It's different from rising or penetrating damp, which involve water entering the building. See the types of damp explained.