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Get The Drop On Window Condensation

Category: Blog, Service & Maintenance, Tips and Tutorials

Simple ways to prevent window condensation in your home.

You know the scene. Tim and Lex stranded as their breathing starts to quicken, the car windows begin to fog, and T-Rex attacks. Rose’s hand sliding down the steamy window in Titanic. Or when Uma Thurman puts a line through Kill Bill’s name on the fogged up window at the sword maker’s place.

Window condensation – it’s great for adding drama.

But you don’t want that kind of drama at home, so let’s take a look at some simple ways you can prevent condensation on your windows.

Picture of a fogged up window with condensation on it.

Photo by AJ Jean on Unsplash

Three types of window condensation

Don’t want the drama of window condensation and wondering what you can do about it? The answer depends on what type of window condensation you are dealing with.

1. Interior window condensation

This blog article is about condensation that forms on windows on the inside of your house, also known as interior window condensation. Interior window condensation is characterised as foggy windows that you can draw on with your finger.
  • Seen as droplets of water on the inside of the window
  • Does not indicate there is anything wrong with your windows
  • Wipe away condensation when you see it
  • Reduce humidity in your home to prevent it occurring
  • Can cause damage if excessive

The other two types of window condensation are:

2. Exterior window condensation

  • Seen as droplets of water on the outside of the window
  • Does not indicate there is anything wrong with your windows
  • Wipe away condensation or let it evaporate naturally
  • Can appear even on energy efficient windows

3. Window condensation between your double glazing

  • Seen as moisture in between the two panes of glass in an insulated window
  • Indicates a problem with the airtight seal on your IGU (Insulated Glass Unit)
  • Moisture does not tend to evaporate due to limited airflow between the two pieces of glass
  • Window replacement is the ideal solution



  • Condensation on windows occurs when the air in the room is warm and humid, but your windows are cool
  • Droplets of water form on the inside of your windows – not to be confused with leaking windows
  • Commonly occurs in winter, and in rooms with insufficient ventilation
  • Can be prevented by improving ventilation in the room to reduce humidity


What is interior window condensation?

Common during winter and in rooms with insufficient ventilation, interior window condensation is noticeable when your windows become foggy and droplets of water form on them.

This happens because the temperature of your windows are cooler than the humid, warm air that is in your room.

As the warm air comes into contact with the colder surface of your windows, the air cools and its moisture condenses on your windows.

What causes interior window condensation?

Condensation is usually first noticed on windows and glass panel sliding doors because they tend to have the lowest temperature of any of the visible surfaces in your house. Because of this they are often singled out as the cause, but in reality they act as a warning sign that humidity may be too high in your home.

Indoor air humidity can be caused by everyday living:

  • Putting the kettle on to boil
  • Airing clothes out to dry inside your home on rainy days
  • Having hot showers
  • Fish tanks and indoor house plants;
  • and even breathing

So consider window condensation as a symptom and not a cause of high humidity in your home.

Is interior window condensation bad?

Condensation on windows in itself is not bad. It’s simply a tell-tale sign that the humidity in your home may be too high.

But high humidity in your home can lead to health issues and maintenance problems:

  • Bacteria and mould can take hold in humid conditions, and spending too much time in a high humidity environment may cause respiratory problems or trigger allergies
  • Excess moisture from high humidity can cause peeling wallpaper, damp patches, stains and discolouration of your walls and ceilings, and can even damage window sills if the water droplets continuously pool there

Controlling the humidity levels in your home is important for creating a comfortable living environment, saving on energy costs, and reducing health and maintenance related issues.

A little fog on your windows is OK, but you should investigate the cause and take corrective action if you notice excessive condensation on your windows and cold walls.

A typical house may produce in excess of 20L of water vapour per day!

How to stop interior window condensation

The best way to control condensation is to keep the relative humidity low. Following are several easy steps you can take to reduce moisture in your home and stop window condensation.

7 tips to prevent interior window condensation:

  1. Open windows slightly to improve ventilation
  2. Close bathroom doors when having a shower to prevent moisture in the air from escaping into colder rooms
  3. Use exhaust fans during and after showers and baths, and when cooking
  4. Ensure exhaust fans are vented externally and not just into your roof cavity
  5. Keep your windows open when using a clothes dryer, or dry clothes outside in a sunny spot
  6. Cover up your aquarium to prevent excess moisture in the air
  7. Ensure your windows are correctly and adequately sealed

The Australian Glass & Window Association (AGWA) also provide useful information on managing window condensation.


About the Author

Dempsey O'Callaghan - Service Manager

Dempsey O’Callaghan is the Service Manager at Jason Windows. Our Servicing and Spare Parts Team include 13 specialised Service Technicians fully trained on over 150 unique service tasks which may arise in the course of their day. It takes several years to master all of the facets of our Service Technician roles and many of our Service Technicians are also qualified glaziers. Our Servicing Support Team work behind the scenes to ensure that an average of 100 jobs are booked in and scheduled each day.

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