What Causes Condensation On Windows?

Condensation on windows is a common concern, particularly in the colder months when we keep warm air in and cold air out by reducing ventilation in our homes. 

Condensation can be annoying and inconvenient, but taking steps to tackle it can reduce serious structural and health problems in the future. In this guide, we show you a few tips to combat condensation yourself and how we can help with the more permanent solution of double glazed windows. 

What is condensation?

Put simply, when gas or vapour changes into a liquid, that’s condensation. Although we can’t see it, the surrounding air in our homes always contains water vapour. If you watch the steam from a boiling kettle, it gradually disappears as it is absorbed into the atmosphere.

If the temperature of an object (glass, grass, metal for example) falls below its ‘Dew Point’ temperature, water vapour from the atmosphere liquefies into water droplets on its surface. The term gets its name from morning dew on the grass, a result of heat moving upwards on cold nights and the temperature of the ground dropping below the air temperature, with the water vapour forming dew. A similar example is breathing on a mirror – the saturated exhaled air is a higher temperature than the mirror is at room temperature.

So each time you put the kettle on, take a shower, use the tumble dryer, water houseplants or even exhale, you are unsuspectingly adding water vapour into your home. 

What causes condensation in a house?

Before our energy-efficient modern houses existed, homes featured air vents, chimneys and poorly fitted doors or windows that allowed air to circulate freely and naturally around the property. Homes today trap moisture inside, and this lack of ventilation causes condensation. 

What causes condensation on the inside of windows?

Condensation on windows occurs when warm, moist air and cold windows collide. But it doesn’t just gather on windows, it can also occur anywhere cooler than the air temperature in a damp room, including the inside of wardrobes and on north-facing walls. 

Condensation between the panes of glass of double or triple glazed happens when the seals on the sealed unit begin to fail and more moisture is drawn into the unit. Between the panes of multi-paned glass is crystalline desiccant, the absorbent material that you also find in sachets in new bags and shoes. If this becomes oversaturated condensation then forms inside the unit. 

You might notice frequent condensation on your bedroom windows in the morning. You might be surprised to know this because two sleeping adults produce approximately a litre of water in 8 hours!

Can condensation on the inside of windows be dangerous? 

At the very least, condensation will obscure the view through the window, but paint and varnish can peel, and leaving the water to pool around the sills and frames can cause metal to rust and wood to mould and warp. 

Condensation can also cause mould that manifests as black spots on walls and ceilings. This needs to be addressed as soon as possible, as breathing in mould spores can be very bad for your health, and can lead to minor respiratory problems. 

What causes condensation in new double glazed windows?

New windows should never have internal condensation, so if you experience this there is an issue with the seals which should be covered under the manufacturer’s warranty.

What causes condensation on the outside of windows?

In the summertime, if you see condensation on the outside of your windows in the morning, this is perfectly normal so there’s no need to panic. This is because the temperature of the air is warmingly quickly against the cold glass, but it will clear when the glass is warmed by the sun.

How to stop condensation on windows 

Thankfully, there are many ways to curb condensation, from simple solutions to long-term options. 

1. Open windows 

It might sound very straightforward, but opening your windows even a tiny bit will help reduce the room’s humidity and prevent condensation. You don’t need to open them all night long; just half an hour after you wake up, have a bath or shower, or cook will make all the difference. Don’t forget to open curtains and blinds as well, to prevent mould and improve air circulation around the window. 

2. Fit an extractor or ventilation fan 

It’s a great idea to have an extractor or ventilation fan fitted in your kitchen and bathroom as these are rooms that regularly produce a lot of water vapour. 

3. Invest in a dehumidifier 

Dehumidifiers are great at collecting water from the air, keeping rooms free from damp and mould and reducing clothes drying time. According to Home Air Guides, an average-sized humidifier for residential space collects up to 20 litres of water over a day. The cost to run a dehumidifier isn’t as high as you might think, Ideal Home calculates that a 20 litre dehumidifier with a wattage of 480w costs just under 16p for an hour’s usage. 

4. Laundry tips

Ideally, dry your washing outdoors on a bright day. If you’re drying clothes inside, keep the laundry room door open, the room well ventilated and double up with a dehumidifier. And never dry clothes on radiators – use a drying rack. 

5. Keep the heating on 

With the energy crisis upon us, keeping the heating on may not appeal, but a low temperature all the time is better to reduce condensation than turning off the heating at night and then having radiators on high when you wake up. 

6. Invest in moisture-loving house plants 

Did you know that humidity-loving houseplants, such as orchids, bromeliads and tillandsia, absorb moisture from the air?

How double glazing can help reduce condensation 

One of the best solutions to permanently eliminate condensation is to choose double glazed windows. 

The glass in a single glazed window is vulnerable to cold temperatures, which is why they often attract condensation. If the window has a wooden frame, this is also susceptible to damage.

As the glass is warmer in double glazed windows, they help reduce condensation as the gap of air inside the glazing works hard to keep the internal pane of glass nearer to room temperature, stopping the water vapour from reaching its dew point.

Not only are double glazed windows less likely to experience condensation, they are more energy efficient and will keep your rooms warmer. That means more heat, less condensation, and smaller energy bills. 

As brilliant as they are at reducing condensation, double glazing doesn’t eliminate it completely, but by using them combined with the tips above you will notice a huge difference. Another bonus of modern windows is that they can be left open securely, as they have multi-point lock settings.

If you would like to find out more about our double glazed windows, please get in touch, we’ll be happy to help. 

In summary 

Condensation is not only annoying, but it can lead to damage to your home and your health. Finding the cause of the problem is the first step to take, then to combat condensation you need to improve ventilation, remove moisture and consider installing double glazed windows.  

How we can help

We have been helping people have warmer, more secure homes with our quality windows for over 40 years and are here to assist if you’re experiencing condensation in your home. 

Our A-rated windows are accredited by the British Fenestration Rating Council (BFRC) for their energy efficiency and are available in a wide range of colours and styles. We offer a 10 year guarantee on all the products manufactured at our site in Bristol and installed by us, to give you complete peace of mind. 

If you need any help or advice, then please get in touch

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