Condensation on windows is one of the most common winter problems in UK homes. It happens when warm moist air inside the house hits cold glass and turns into droplets. If it is not managed it can lead to mould, musty smells and damage to window frames.
Why condensation appears in the morning
Overnight, rooms often cool down because the heating is off and the air is still. At the same time people are breathing in the room which adds moisture into the air. By morning you have a simple recipe: warm moist air inside and cold glass outside.
When that warm moist air touches a cold surface it cools quickly and the water in it turns into tiny droplets. This is what you see running down the inside of the window.
What makes it worse
- High indoor humidity – if humidity is above about sixty percent you are very likely to see condensation on cold mornings.
- Poor ventilation – closed trickle vents, sealed windows and no fresh air keep moisture trapped inside.
- Drying laundry indoors – a single load of washing can release more than two litres of water into the air.
- Heavy curtains close to the glass – this makes the air by the window even colder and more likely to turn to droplets.
Simple ways to reduce it
- Open bedroom windows for five to ten minutes each morning to let humid air escape.
- Keep trickle vents open on modern windows where possible.
- Avoid drying laundry in bedrooms and small rooms if you can.
- Move furniture a few centimetres away from cold external walls to improve airflow.
- Leave curtains slightly open at the top so warm air can reach the glass.
How a dehumidifier helps
A modern dehumidifier removes excess moisture from the air before it has a chance to settle on cold surfaces. Running one for a couple of hours in the morning or in the evening can reduce window condensation dramatically.
If you want to see some proven options that work well in UK homes, take a look at our page on the best dehumidifiers for UK homes.
When to take action
If you see condensation every morning and also notice black spots around frames, musty smells or peeling paint, it is a sign that humidity has been too high for a while. In that case tackling moisture should be a priority before the damage gets worse.
The good news is that small changes to ventilation, drying habits and dehumidifier use are usually enough to stop windows dripping every morning.