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How to Stop Condensation on Windows

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How to Stop Condensation on Windows

By Ruth MacEachern

Product Manager

Feb 08, 2023

During the winter, it’s not unusual to see patches of condensation on your bedroom windows.  The condensation forms during the night, and the amount of water on the glass and windowsills by the morning may be surprising.

On its own, condensation on your windows is not a significant problem, but if it is not dealt with, the moisture can soak into wooden window frames, causing them to rot.  It is also important to remember that although condensation is most visible on windows, it can form on any cold surface in your home.  Suppose condensation is also developing on your walls and ceilings. In that case, it can quickly lead to patches of damp that damage plasterwork and offer the perfect environment for potentially harmful mould growth.

Where does condensation on windows come from?


The condensation on your windows in the morning is caused by warm, moist air coming into contact with a cold surface.  The amount of water vapour that the air can hold depends on temperature, and when the air cools, the moisture is released as droplets on the surface.

Many of our day-to-day activities contribute to the amount of moisture in the air.  Common sources of moisture release including cooking and bathing as well as drying clothes on radiators.

The main contributor to water vapour during the night is simply breathing!

Every time you breathe out during the night, some water vapour is carried in the air.  If your bedroom door and windows are closed, that moisture is trapped and will eventually come into contact with the cold surface of your windows, causing condensation.

Preventing condensation on windows

To reduce the amount of condensation that can form on your windows, it is important to reduce the humidity levels in your home. There are several ways that you can do this.

Improve your domestic ventilation

The most effective way of reducing condensation is to improve the ventilation in your home. 

Ideally, a home should have extractor fans located in the following rooms:

  • Bathrooms
  • WC’s
  • Kitchen
  • Laundry room / Utility Room

These “wet” rooms are the primary sources of moisture in your home’s air.  By installing sufficient ventilation in the form of extractor fans in those rooms and using them when you are cooking, bathing, or washing clothes, you prevent the moisture from those activities from escaping into the rest of your home, where it can cause condensation.

Whole house ventilation systems such as ATMOS – a Positive Input Ventilation System – help improve air circulation in your home.  This creates more even temperatures throughout your property and reduces the amount of time that moist air spends in contact with cold surfaces, and is the most effective way of preventing condensation from developing into worse problems such as damp patches and mould.

Reduce the amount of moisture in the air

The condensation that can form on your windows and walls comes from the water vapour released in your home.  There are steps you can take to reduce the amount of moisture that is released into the air.

Use pan lids when cooking and ensure that your kitchen extractor is working.  This reduces the amount of steam released from pans into your home.

Start filling your bath with cold water and add hot water.  By doing this, the amount of water that evaporates from a hot bath is reduced.

Avoid drying clothes and towels on radiators. If you pick up a damp towel or wet clothes, you can feel the difference in weight from the absorbed water. As the fabric dries on a radiator, all of that moisture is released into the air, which it will eventually lead to condensation.

Open windows when the weather is warm. Condensation can form on windows throughout the year but is most common in winter.  During late spring and summer, leaving your bedroom windows open overnight allows the moisture that you exhale during the night to escape from your room and reduces condensation.

Do you want to prevent condensation on your windows?

Are you waking up each morning to see condensation on your windows and worried about it leading to damp and mould?  We can help. We have ventilation specialists across the UK who can visit your home to perform a free survey that will identify the causes of condensation and advise you on the best way to prevent it.

Simply enter your postcode below and find a ventilation specialist in your area.

Need help with condensation, mould or damp problems?

One of our local experts will contact you to learn more about your problems, offer free expert advice and make recommendations for a permanent solution.

During the free survey we will

  • check Assess any condensation, damp or mould problems in your property
  • check Take readings of the relative humidity levels
  • check Identify any underlying problems and make recommendations for a permanent solution

Arrange a FREE Home Survey now