Why your windows get condensation and how to stop it

You wake up, go to look out of the window but are confronted with a view obscured by a film of water droplets.

Damp autumn or winter mornings are when you are most likely to see this.

Condensation forming on either the inside or outside of your window depends on a few factors but ultimately it is caused by a difference in air temperature and humidity.

There are some things you can do to try and prevent condensation, especially if it's happening on the inside of your house.

The air around us holds moisture and the amount can depend on the weather conditions outside but also things like whether you are cooking or showering for example.

Cold air holds less moisture than warm air. So if the air temperature drops it will get to a point when it can no longer hold any more and becomes 100% saturated. The temperature at which this happens is known as the 'dew point' temperature.

Once air has cooled down to its dew point you will start to get water droplets forming on any colder surface.

We commonly see this as dew on grass or on your car windows in the morning after a cool night.

If you are getting condensation on the outside of your window, this probably means you have got double glazing or highly efficient windows.

It is quite common and proof that your windows are doing a good job of keeping the heat inside your home.

The window insulation means that the outside pane of glass isn't being warmed up by the heat from inside and stays cold.

On a typically humid and still night, the air very close to the outside of the window is cooling down below its dew point temperature with water vapour eventually condensing into droplets on the cold glass.

Exterior condensation will evaporate once air temperatures start to rise through the morning or there is sunshine to burn it off.

Condensation on the inside of windows essentially happens when a glass window isn't very efficient and allows heat to escape, thereby getting colder on the inside.

Your room will be full of warm humid air but as the temperature drops overnight and the glass gets colder, a thin layer of air next to the glass window is also cooling down.

Eventually the water vapour in the air cools so much that it condenses into water drops on the window pane.

Condensation on the inside can depend on how humid it is in your house and how good your ventilation is.

Cooking, showering or drying clothes inside will all increase the amount of water vapour.

Inside condensation can be easier to manage.

Try and avoid it getting too humid inside a room so open windows and increase ventilation when cooking or showering.

Avoid drying clothes inside too as this increases moisture build up.

You could also try and not use curtains or blinds that might block moisture close to the window.

Dehumidifiers can be useful to reduce the amount of moisture in a room and would cut down the amount of condensation.

Most experts recommend that you remove the condensation from your windows regularly with a dry cloth to prevent water damage to the frames and conditions where mould can grow.

It is much harder to stop condensation on the outside of your windows. Ultimately it is a sign that windows are working effectively in keeping heat inside your home.

You may only find it occurs on some of the windows depending on their orientation to the rising sun or if they are sheltered.

Again you could try and keep them as dry as possible by wiping after rainfall or apply a coating to repel water drops.