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Window condensation – what causes it and how to reduce it.

Comments (0) Advice, Window Maintainence

What causes condensation?

Condensation forms when warm or humid air contacts a cold surface. Moisture is in the air all around us and warmer air can hold more moisture. When the air around us cools it contracts and condenses,  and when the temperature drops, the first place you will see any condensation is on the windows.

Windows are the coldest surfaces indoors as they are our portal to the outside world. During colder months, indoor air is much warmer and holds more moisture than the outdoor air which is colder and dry. Warm and humid indoor air cools and contracts as it comes into contact with the cooler windows, the moisture then condenses on the glass.

Why is indoor air humid?

Everyday activities cause indoor air humidity such as taking a shower,  having a bath, cooking, washing dishes, doing your laundry, cleaning and even breathing. These all add moisture to the air in your home, in some cases, as much as 1.6kg of moisture per day per person!

Here is a breakdown of how much moisture is released from some normal day-to-day activities:

  • Cooking with gas cooker: 3,000 g/day
  • Cooking with electricity: 2 000 g/day
  • Dishwashing: 400 g/day
  • Washing clothes: 500 g/day
  • Drying clothes indoors: 1,500 g/day
  • 15-minute shower: 600 g

Therefore, keeping your house well ventilated is crucial and however much we want to keep the warm air in its vital we let the moisture out and maintain regular airflow. This can help prevent future  problems  such as rot or mould which are bad for you and your home.

I have condensation on my windows – are bad seals or indoor humidity causing the problem?  

Try running your finger through the area where the condensation is formed, if your finger gets wet and leaves a trail through the condensation, it’s on the room side of the glass – thus telling you that condensation is forming because of excessive indoor humidity and poor ventilation in your home and windows. In this case  it is unlikely to be your seals.

If the condensation is actually in your window, then this could be to do with your seals and they might need replacing. Over time seals can become worn from weathering. If you have this problem please do not hesitate to get in touch with one of our experts who can offer a free survey to determine the best treatment.

How can we reduce indoor humidity?

  1. Increase ventilation -Open a window in each room for just a few minutes each day, letting humid air escape and fresh, dry air in. Your heat loss will be minimal. Also, when you are drying clothes indoors try and open a window, even if just slightly, to help with air flow and to let some of that excess moisture out.
  2. Increase ventilation– Installing an extractor fan in your bathroom could help, as well as keeping your windows open when you have a shower or bath. Ensure your extractor fan is on when cooking will also help, and if you have a tumble dryer, make sure it either has a shoot to the outdoors, or, if it is modern tumble dryer and can absorb the moisture for you, then make sure to dispose of the water regularly.
  3. Move your plants -If you notice larger amounts of condensation where you have plants, then it can help to – move them away from your windows as they release moisture into the air .
  4. Spring clean!– Try cleaning the fogged windows to remove any build-up that isn’t condensation on the glass.
  5. Restoring old windows – This can be a big help with ventilation and is relatively inexpensive. Restoring windows can not only help keep valuable hot air inside, but can also aid the circulation of moisture if fitted with small ventilators. It can also mean your seals can be replaced and therefore help with moisture control, especially if you have condensation between the panes.

Why is condensation bad?

Condensation can reduce the lifespan of a window as it will encourage the growth of mould which can damage the frame.  It can also be taken as evidence that the humidity inside your home is excessive which can be a health concern. So, although it is a problem which most households will see at some point, and is often no more than a warning to open a window, if neglected it can lead to more serious problems.

We suggest trying our top tips as above however if you see no improvement and the problem reoccurs, then give us a call and we can offer you a free consultation to find the best and most cost-effective solution for your windows.


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