Why do I have condensation on my windows?

Let’s talk about one of the biggest topics of conversation regarding windows… condensation on the internal glass surface.

In this article, we are going to discuss what causes condensation to appear on the internal surface of your glass and how you can reduce and manage it.

Let’s dive in….

It’s not fun to wake up to see wet and moisture-covered windows and glass caused by condensation, so before we discuss how to reduce condensation on your windows, it’s important to understand what it is and how it’s caused!

What is Condensation?

Condensation is caused by the presence of excess moisture that forms water droplets when it comes into contact with a cold surface, in the case of our windows that surface is the glass.

In warmer air, the molecules within it are spread out, as the air gets colder the molecules come close together, and as they get closer and closer they become a visible liquid. This is known as the ‘Dew Point’.

A great example of this would be the condensation you see on your bathroom mirror after a shower or bath.

It’s worth remembering that condensation as we’ve just discussed can form on any cold surface such as blinds or even furniture which is rested against a cold wall

What causes condensation on the inside surface of the glass?

Condensation on the interior of windows occurs when warm, humid air meets the cold surface of the glass. This is especially common in the winter when the outside air is cold and dry, and the indoor air is warm and humid. Even everyday activities such as showering, cooking, and sleeping can contribute to the issue and increase humidity levels.

Your initial reaction may be that your windows are at fault, if this is the case, we may have some good news for your wallet – It’s probably not your windows!

UPVC windows are meticulously designed to be as airtight and energy efficient as possible, great news for your energy bills, but not so great for the level of humidity in your home. The lack of ventilation in your home increases the humidity level which therefore increases the condensation issue. Think of condensation on your windows as an indicator to reduce the humidity in your home before bigger issues occur. Below is a list of just some of the things that may be contributing to your condensation issue:

- Showering
- Drying clothes
- Lack of ventilation
- The extractor fan is not being used
- Leaving internal doors closed
- Furniture touching walls
- Poor insulation

Now we know what’s causing the issue, how can we reduce it?

Reducing Winter Window Condensation Inside Your Home

Condensation on the interior side of your windows is most common in the winter. But it can happen at any time of the year, factors such as window location, which direction it faces and even the trees located nearby can have an effect. Either way, there is lots we can do to improve the situation, try these simple ways to help cut down on the humidity in your home:

1) Use Kitchen and Bathroom Extractor Fans (… for longer)

Every time you cook or shower, huge amounts of moisture are released into the air. Sometimes it’s tough for moisture to easily escape from your home – especially if you have a new build home that’s tightly sealed and retains even more moisture than older homes. When cooking, keep excess humidity contained by covering pots and pans.

Run the extractor fan to help remove moisture from the air. The same goes for bathroom fans. Leave the bathroom fan on during and after a shower to help circulate humid air out of your home. We recommend running extractor fans for about 20 minutes after you cook or shower.

2) Dry clothes in well-ventilated rooms

During the winter months, it’s nearly impossible to dry clothes outside, so when doing so inside, make sure you choose a room that’s well-ventilated or with an opening window, you can even pick a room with an extractor fan such as the main bathroom.

3) Leave Interior Doors Open and Circulate the Air

Another way to help reduce window condensation is by circulating the air around your home. Leave interior doors open throughout your home to prevent humidity from building up in one space. You can also circulate air by opening your windows. This will let out some of the moist air that may be trapped in your home.

Top Tip:
Use the night latch on your window lock to secure the window slightly open allowing some airflow.

4) Use a Dehumidifier

In extreme cases, one way to reduce air moisture in your home is to use a dehumidifier. Dehumidifiers are electrical devices that help extract water from the air. Many people purchase dehumidifiers to eliminate musty odours and prevent mildew, mould and bacteria, but dehumidifiers can also be used to reduce condensation on windows.


To summarise…

To summarise, condensation on your windows is fairly common, and in many cases, it doesn’t mean your windows are faulty, the most likely cause of the condensation is a lifestyle and general living within your home.

Additions such as additional trickle vents or new windows will not solve the issue in most cases, but some awareness of what causes humidity and condensation will go a long way to improve the situation.

We hope the above has been useful for you and answered some questions about the topic of condensation.


If you have any further questions about condensation or window repairs in general or wish to speak to a member of the team then don’t hesitate to get in touch with us at 01455 850282 or shoot us an email!

We look forward to helping you soon, and remember - Why Replace... We Repair...