How to stop condensation on windows from ruining your home

mould on window with condendation
(Image credit: Getty)

Understanding how to stop condensation on windows is important for several reasons. Firstly, water running down your windows is just not a good look, but it is also a cause of damp, mould and mildew in a home. It can also cause damage to your window frames and cills, as well as your walls.

Window condensation occurs when any excess moisture hanging around in the air in your home condenses on the inside of windows. 

There are several reasons why you might have too much moisture in your home, but it is commonly caused by a lack of good ventilation, which means excess moisture can't being extracted from the air. It can also be caused by inadequate insulation, causing the damp air to hit a cold window, creating water droplets. 

Condensation can occur on walls and other surfaces, but many homeowners notice it on windows as it causes a 'steamed up' effect or, perhaps worse, water streaming down the panes and pooling on the window cills. 

In this guide, we explain, with the help of experts in the field, how to deal with condensation on windows and what you can do to prevent this from happening in the future.

How to stop condensation on windows

In an ideal world you wouldn't have a condensation problem to deal with in the first place — and this is where preventative measures come into play. 

There are a few easy ways to reduce the chances of condensation on windows, some are short-term solutions and others are long-term ways to prevent the problem from occurring in the future. 

Before getting into how to how to stop condensation, it is useful to understand why it occurs in a little more detail. 

"There are three factors that determine whether condensation forms on your windows: the level of moisture in the air, the air temperature of the room and the surface temperature of the windows," says Chris Michael, managing director of UK air treatment specialist Meaco. "The more moisture there is in the air, the more likely it is that condensation will form. Much of this moisture is difficult to avoid though, as it comes from day-to-day activities such as drying clothes indoors, boiling vegetables, turning on the kettle, bathing, showering, and even breathing.

"The warmer a room is, the more moisture the air can hold, and the colder windows are, the greater the difference will be to be between the air temperature and this surface temperature. A greater difference increases the chance of condensation forming. When windows are colder, less moisture is required for condensation to happen, which is why we see less condensation in warmer weather when windows aren’t as cold," continues Chris.

"To prevent condensation on windows, there are three main steps to take: ventilation, insulation and clearing moisture," explains Louis McGee, glazing expert at Cloudy2Clear.

We asked a range of experts for their top tips on the best way to prevent, reduce and solve window condensation so you can look forward to opening your curtains in the morning rather than dreading what you'll find. 

1. Throw open windows and doors

One of the cheapest and easiest ways of reducing window condensation is to let fresh air flow around your home. 

"Simply opening a window and airing a room for 10-15 minutes a day will make a massive difference to the build-up of moisture in the home and is enough to exchange the air in an average sized room," says Ryan Schofield, managing director of Thames Valley Window Company.

That said, you do need to think of the downsides of relying too heavily on this method.

"Opening a window is a simple act that can help remove condensation, but this is only a temporary fix and has added repercussions," warns Chris Michael. "The new air coming in from outside could be colder, requiring your heating system to work harder which will increase heating bills. Additionally, outside air may not be as clean and could bring in allergens and pollutants.

"You also need to consider how safe it is to leave a window open, and whether the air coming in is actually dryer than the air going out. Average relative humidity (RH) in the UK is often high enough throughout the year to create mould in your home (above 68% RH), and is certainly high enough to cause condensation."

buiding regulations part f covers ventilation

Aim to open windows on a daily basis to get a good air flow through the house.  (Image credit: getty images)

2. Look for simple ways to reduce moisture levels

Have a think about those everyday activities that take place in your home that cause additional moisture and aim to either reduce them or take steps to offset this additional moisture when it occurs. 

"Actions like putting lids on saucepans when cooking, doing an extra spin cycle when using the washing machine to avoid excessively damp clothes drying, and using the best bathroom extractor fans you can find when showering can help a lot," advises Chris Michael. "However, producing moisture is impossible for us to avoid entirely."

Drying clothes outside, where possible, will really help reduce indoor moisture levels. Also ensure vented tumble dryers are adequately vented outdoors.

steamy kitchen

Even taking simple steps such as reducing the amount of cooking steam allowed to escape into your home can help.  (Image credit: Getty Images)

3. Buy an inexpensive moisture collector

Another cost-effective way of cutting down on condensation is to buy a couple of moisture collectors or absorbers and place them in those areas of the home most prone to excess moisture.

These are basically small plastic boxes containing (usually refillable) gel or crystals which absorb moisture. When placed near a window they will absorb the moisture before it has chance to settle on the windows. 

You can pick up something like the highly rated ANSIO Pack of 5 Condensation Removers on Amazon for just £9.75. 

Associate editor Natasha Brinsmead tried the Unibond Aero 360 (available on Amazon) and said it dramatically reduced the amount of water pouring down her windows. However, while it reduced condensation it didn't stop the problem entirely.

4. Invest in a dehumidifier

For many people, the very best way to reduce and even eliminate window condensation is to bite the bullet and invest in a dehumidifier — but just how do dehumidifiers work?

For dealing with most home condensation problems, compressor dehumidifiers tend to be the best option (as opposed to desiccant).

"This type of dehumidifier draws in the air and compressors have a cold-coils system, like a fridge," explains Chris Michael. "These types of dehumidifiers are often also referred to as ‘refrigeration dehumidifiers’. They have two sets of coils, the first cools to create the condensation, which is collected into the water tank, the second warms the dry air back to just above room temperature. This helps to create the dry air needed to combat condensation, mould and damp problems."

"The best way to reduce condensation is using a compressor-driven dehumidifier equipped to deal with European climates, which can be very cold or warm and have high humidity levels," advises Joe Pascoe, CMO/CCO at Wood's Professional.  

With Black Friday just around the corner, take advantages of some of the early deals currently available. You can save £103 on the electriQ 25L Low-Energy Smart Laundry Dehumidifier and HEPA UV Air Purifier from Appliances Direct right now or 11% off the Meaco Portable Dehumidifier DD8L from Amazon

MeacoDry Arete® One 20L Dehumidifier/Air Purifier

A dehumidifier, such as this one from Meaco, can have a huge effect on reducing window condensation.  (Image credit: Meaco)

5. Mop or hoover up condensation quickly

If you do find condensation on your windows, despite your best efforts, it is important to deal with it quickly to avoid it causing damp or damage to the woodwork around your windows or you walls. Window vacuums are a quick means of removing condensation from windows in the morning.

"Cleaning up condensation with a Kärcher Window Vac can get instant results with a simple swipe," suggests Rossi Salvatore, assistant product manager at Kärcher. 

"Kärcher Window Vacs are also a great time-saver as the powerful and rechargeable lithium-ion battery can clean up to 75 windows on one charge — getting the job done three times faster than conventional cleaning methods. What’s more, window vacuums can be used on any flat surface in the home including windows, showers, and mirrors, ensuring they all stay spotless and streak-free."

Right now, you can pick up the Kärcher WV 2 Plus Window Vac from Amazon for £49.99 — 33% lower than usual. 

6. Keep your heating at a low and constant level

Warm up the house by putting central heating on to reduce the dew point (the point at which moisture from the air turns into water droplets). This works best by having the heating on low constantly, rather than turning it on only when the house feels cold. A steady, warm temperature is best, but as a minimum make sure your heating turns on when the house is at its coldest. 

"Issues with condensation are intensified by sudden rises and drops in temperature, as each fluctuation causes water to evaporate and condense when your central heating turns on and off," explains Louis McGee, glazing expert at Cloudy2Clear.

"Rather than allowing your heating to swing between hot and cold, keep your heating on a constant low temperature. This will help to prevent damp from forming in your home."

7. Consider installing a PIV system 

"Positive input ventilation (PIV) is designed to control condensation and offers a highly effective solution to eradicate mould and improve indoor air quality," says Natasha King, RMI production manager from Vent-Axia

PIV units are generally installed in the loft, with a distribution diffuser mounted in the ceiling in the room below. The continual supply and slight positive pressure result in the air in the property being continually diluted, displaced and replaced to create a healthier indoor air quality. 

"PIV systems dilute moisture in the air and provide fresh, filtered, tempered air into the home that is drier than the inside air. PIV with additional heating function also helps increase the incoming air temperature. This creates a healthy indoor environment and reduces the risk of condensation and mould, benefiting both the occupants and the structure of the building."

8. Think about upgrading your home insulation

For less efficient houses, one of the best investments to make is to look at the best types of insulation

While this could include cavity, internal or external wall solutions, as well as looking at how your loft and roof are insulated, don't overlook the effect that proper draught proofing can have. Even adding something like the Yotache Foam Seal Tape from Amazon can make a difference. 

Draught proofing windows is an efficient and cost effective way to ensure your house stays warmer for longer. 

9. Consider window replacement or repair

This is a more extreme option, but better insulated windows – in the form of highly efficient double glazing or triple glazing – deliver greater thermal performance and reduce cold spots. If yours are old and past their best, then this could be a good option.

“As well as significantly reducing noise pollution, triple glazing is an excellent solution to condensation. Due to the difference in U-values between double-glazed windows and walls, cold patches can appear in your home," claims Allan Reid of Art Windows & Doors.

"This problem is further exacerbated by modern wall insulation, as the windows become even colder than the rest of the house. Triple glazing offers the best solution, as it dramatically decreases the difference in U-value between your walls and windows.”

However, condensation outside windows can just as easily appear with highly efficient double and triple-glazed units — this is not condensation to be worried about as it won't cause damp and mould internally. 

new build home with uPVC grey windows

Upgrading your windows or glazing can, in some cases, help with condensation — although this is not a cheap option.  (Image credit: Rehau)

10. Design in a MVHR system

MVHR (mechanical ventilation with heat recovery) systems are now being installed in many more self builds and there is a good reason why. 

"As we build better insulated, more airtight homes, the need for suitably designed ventilation systems (that go beyond more traditional methods such as trickle vents and bathroom and kitchen extractors), to deliver fresh air, is even more important," explains expert in sustainable building methods and energy efficiency Tim Pullen.

"The benefits of MVHR systems can also be numerous; from helping to improve air quality for those with allergies and respiratory diseases, to reducing issues such as condensation and mould, which blight many homes."

FAQs

Why am I getting so much condensation on my windows?

"Condensation on the inside of our windows and doors is the result of water vapour having nowhere to go," advises Ryan Schofield. "Water vapour is caused by everyday things such as breathing, cooking, drying clothes, bathing/showering, etc. We can generate 1-2 litres of water vapour every day simply through breathing! 

"A three-person household can generate approximately 180 litres – more than a bath tub of water – every day. It is essential, therefore, that the correct amount of airing and ventilation occurs."

"Condensation is a common problem but if undetected, it can result in damage to furniture, mould growth, mite infestation, unhealthy living conditions, poor indoor air quality and damage to the structure of the building," says Vent-Axia's Natasha King.

Should I wipe condensation from windows?

"On surfaces like windows, mirrors, shower screens or tiles, condensation will remain visible but can be wiped away, however on wood or plaster, the moisture from condensation can be absorbed into the material and over time will create damp patches which may cause damage to sills, frames and surrounding walls," explains Rossi Salvatore from Kärcher. 

If condensation is not removed from walls and window cills this can lead to timber rotting and having to look at removing mould from walls.

Will fitting new windows help?

"Although it may not be welcome, it’s important to be assured that condensation on the inside and/or outside of your windows is proof that your windows are doing their job of preventing heat loss. What you are seeing is energy efficiency in action," says Ryan Schofield.

"Often, we replace our windows because they are no longer energy efficient. They may be old windows with single glazing, or double-glazed windows that are long past their best. Condensation doesn’t get a chance to build up because enough air passes through the frames. So, if you have condensation on your windows, it is in fact a sign that your windows are doing what they need to be doing, as opposed to if they aren’t energy efficient and have air passing through them, then they may need replacing."

Do curtains and blinds make condensation worse?

Blinds and curtains can trap moisture between them and windows, increasing the chances of condensation. The best way to avoid this issue is to open blinds and windows early in the morning and especially if you have blinds in kitchens and bathrooms while cooking or showering. 

Great deals on products to stop window condensation

Amy Reeves

Assistant Editor Amy began working for Homebuilding & Renovating in 2018. She has an interest in sustainable building methods and always has her eye on the latest design ideas. Amy has interviewed countless self builders, renovators and extenders about their experiences for Homebuilding & Renovating magazine. She is currently renovating a mid-century home, together with her partner, on a DIY basis, and has recently fitted her own kitchen.