How to stop condensation on windows – 11 expert ways

Experts recommend better ventilation, regulating heating, anti-condensation paint and more, if you're curious about how to stop condensation on windows overnight.

A mid-century style living room with wood flooring and large windows
(Image credit: Peter Fehrentz/ More Moebel)

Condensation on windows is common in all types of homes. Though not just reserved for winter, it's more prominent at that time of year, as the cool weather outside leaves window panes and the air pockets in-between double glazing at a much lower temperature compared to the airflow inside our homes. Here's how to stop condensation in your home – more specifically, on your windows.

Condensation on the inside of windows is actually different from other forms of dampness, such as rain and rising damp. It is water released when air is cooled to its dewpoint temperature and unable to carry so much moisture as vapor – the opposite process to evaporation.

So this can happen indoors whenever warm, damp air comes into contact with colder objects, like windows. If not dealt with, condensation will have you reaching for the best cleaning products and looking for ways to get rid of mold quickly and at worst, dealing with wood decay or an unhealthy living environment.

James Mokler, Retail Assistant Product Manager at Kärcher (opens in new tab) explains, 'The build-up of condensation occurs when the air inside of the room is warmer than the surface temperature of the window (or any surface). As most are turning up their heating during the colder months and keeping up with daily activities such as cooking, showering, even breathing, condensation builds up faster and at a more frequent rate.'

Building and construction expert, Thomas Goodman at MyJobQuote (opens in new tab) adds, 'Typically appearing on windows and doors, condensation can also form in unventilated spaces such as wardrobes and cupboards and cause damp. In fact, condensation is the most common cause of damp in buildings and, if left untreated, can cause black mold, which is harmful to our health.'

Condensation on window panes and mold caused by condensation on walls

Condensation has formed on windowpanes (left); condensation-related mould on walls (right)

Is condensation on windows bad?

'Unwanted moisture in homes can cause structural and aesthetic damage such as mold, damp walls, and ceilings, rotting windowsills and frames, and can be costly to fix if not dealt with early on. Mold and damp also pose a health risk. According to the NHS website (opens in new tab), if there is damp and mold in a home, the occupants are more likely to have respiratory problems such as asthma and allergies leaving babies, children, and the elderly most at risk*.'

There are ways to tackle condensation on windows that can successfully get the moisture balance back in your home, to prevent future condensation on the inside of different types of windows.

Douglas Kent, technical and research director for the Society for the Protection of Ancient Buildings (SPAB), gives us his expert guidance and insights on the causes of condensation in houses and how to avoid them. 

How to stop condensation on windows

In homes old or new, simple lifestyle changes that lower humidity and/or keep surface temperatures above dewpoint will be more practical and a less expensive long-term solution than installing whole-house ventilation systems. 

'Preventing condensation will help keep your home free from damp and mold and can even save you money in the long run, as the longer you leave condensation the worse the problem will inevitably gets,' says Goodman. 

Try these tips below:

1. Ventilate your home

The key is to generate less moisture but some is of course inevitable. So, open windows where you can and avoid draft-proofing windows in kitchens and bathrooms. 

This is especially important if you live in a small, open-plan flat without an efficient extractor fan or air bricks, as there's nowhere for all the moisture to go. So, open the windows often, especially when cooking, and crack them open while you're in bed.  

Mokler recommends even opening the windows for just 20 minutes a day as this can be enough to drastically reduce the effects of condensation and dampness in homes.

Ensure also that lofts, floor voids and redundant chimneys are well ventilated and avoid foam treatments on the underside of roofs that can cause timber decay.

2. Keep heating on constant

Increased home heating systems can maintain surfaces above dewpoint, especially if run constantly at a low level, rather than intermittently. Lagging cold pipes may prevent surface condensation, as can improved insulation levels. 

So to stop condensation from forming, keep your heating on a low setting throughout the colder months. Temperature fluctuations, especially the temperature plummeting around dawn, are very often responsible for condensation forming on windows. 

'Ensuring that there’s a regular warm temperature around your home will stop surfaces from getting cold enough for condensation to build. The heating doesn’t need to be on constantly throughout the day, but a timer can be used to switch on the heating during the coldest periods, keeping surfaces warm and preventing condensation from forming,' says Mokler. The trick is not to blast your home with hot air for short periods of time and leave it cold the rest of the time. An even, continuous low heat setting is better.  

Goodman did caveat this suggestion though, saying, 'This may not be a simple option, especially as heating prices are rising rapidly – but keeping your heating on low, rather than intermittently turning it on high, can help in preventing condensation. However, this shouldn’t be used as a permanent solution, due to the high cost and energy level used.'

There are of course other ways to save energy at home where you can.

3. Invest in better insulation

condensation on a window

(Image credit: Shutterstock)

'If condensation is a recurring issue in your home, it may be worth investing in reinsulating the walls of the house, and window insulation. This will not only keep your home warm and reduce costs for heating, but having good insulation greatly determines how much condensation builds up and how long it takes to dry,' notes Mokler. 

Goodman is in agreement, 'Improve your home’s insulation – this is more of a long term solution that can be costly. However, there are ways to improve your home on a budget. One of the most expensive methods is to upgrade to double glazing windows and doors, as this provides better thermal insulation both in and outdoors. The well-sealed frame also reduces heat loss and air leakage.'

'Ensuring your walls and lofts are properly insulated can also help prevent condensation from forming. Cold spots on walls and ceilings increase the chance of condensation, as there’s more chance of warm air reaching them.'

4. Try anti-condensation paint

Goodman told us, 'Anti-condensation paint is a thick paint that adds an extra layer of insulation to your walls, making it the perfect insulation solution if you aren’t able to actually insulate your walls. It works by adding an extra layer of insulation to walls and prevents condensation from building up. Some paints are used as a pre-paint seal, whereas some are thick enough and can be colored to use as your main coat of paint.'

Ronseal anti-condensation paint (opens in new tab) is easy to apply and does the job.

5. Start cooking with lids

If ventilation is a little poor in your home and in the kitchen more specifically, try and cook with lids on to stop the steam escaping so much. 

'Keeping windows open during activities that cause a lot of moisture in the home such as cooking, showering, and drying clothes, especially if you don’t have great ventilation, can help minimise condensation,' Mokler also recommends.

6. Dry clothes outside

Weather and residence-permitting of course, but damp laundry in an unventilated room is a recipe for water droplets on those windows of yours (and a musty smell as a result of that). 

'Avoid drying clothes indoors if you can,' says Goodman. 'Although this can be difficult, especially during the winter where drying clothes outside isn’t an option, drying your clothes indoors can create condensation and damp issues, especially if you don’t take steps to properly ventilate your home while drying. To prevent such issues, opt for an extra spin cycle on your wash to help extract excess water and make your clothes dry quicker.

'If you have no choice but to dry indoors, for example if you live in a flat, then ensure you position your clothes in suitable conditions. Place your drying rack in front of a bright window to help dry faster and create a well-ventilated area to prevent condensation.'

Of course, using one of the best washer dryers will make this easier and more manageable, too.

7. Keep humidity in its place

Close kitchen and bathroom doors when in use to trap humidity in its tracks. 

'Drawing in moisture from the room before it has time to manifest can be an easy way to combat condensation. Some unconventional methods include putting cat litter in a sock, tying it up and placing it on a windowsill. Putting a bowl of salt on the windowsill has also proven to be a good hack,' says Mokler.

8. Keep dryer vents clear

Keep vent tumble driers to the outside if they are not of the condenser type. And, be sure to clean your dryer vent often to keep it doing its job efficiently.

9 . Turn down your humidifier

If you're using a humidifier, and condensation has recently become a problem, try to turn it down for short periods at a time until you see an improvement.

best dehumidifier: Duronic DH05 Mini Dehumidifier

(Image credit: Duronic)

10. Or, choose a dehumidifier 

'Those in Victorian properties or more traditional homes wouldn't be without one of the best dehumidifiers around, as older homes are more prone to damp and condensation,' Mokler said, 'If you’re able to invest in this solution, there are some great humidifiers on the market which absorb all the moisture in the air.'

You might not want a dehumidifier running at night in a bedroom, but if you put yours on after you get up and time it to switch off an hour or so later, it'll stop condensation and its effects from becoming a problem. And in case you were wondering, dehumidifiers use very little energy (much less than tumble dryers) to run, so you won't see a big hike in your energy bills. 

11. Open your drapes

One of the biggest tips for how to stop condensation is to keep your drapes open to stop trapping moisture and heat on the window panes. This is particularly important in rooms like bedrooms, where droplets can build up overnight.

This will stop wet drapes also which is never nice.

How do you stop condensation on windows overnight?

It is vital to actively tackle condensation before the problem worsens and, luckily, there are plenty of easy fixes to reduce and prevent condensation overnight, without needing too much work.

Open your windows 

By keeping your windows open, you allow the humid air to circulate the room and escape outside. Opening the windows at night, when the outside air is at its lowest damp level, is key as you will release the warm, damp air inside and lower your home’s humidity level.  

Keep your curtains open

Keeping curtains open allows air to circulate against the window, which prevents condensation from forming. If keeping curtains open overnight is difficult, for example, due to streetlights or privacy concerns, then simply investing in thinner curtains can still have an impact, especially if you keep your windows open too.

Leave the exhaust fan on

A common mistake people tend to make is only keeping exhaust fans on while cooking or during a shower. However, leaving it on for longer, ideally overnight, works much better in preventing condensation, as it allows air the chance to properly circulate the room, which reduces condensation,' advises Goodman.

Should I wipe condensation from windows?

You can wipe away condensation on windows using a microfiber cloth but you can also use a window vacuums, like the Kärcher WV (opens in new tab) to quickly remove excess water from inside windows. 

'They’re also a great time-saver as the powerful and rechargeable lithium-ion battery can clean up to 75 windows on one charge. 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,' says Mokler.

Why do I get so much condensation on the inside of my windows?

This is all due to the moisture levels in your home, but it could also be that the moisture is managing to seep through between both window panes as the sealant is old and worn. If it's quite saturated, consider replacing your windows or the sealant. Otherwise, you should be able to sort it out using the above tips.

Is condensation on windows normal?

It is totally normal. Condensation can arise when more moisture is produced – often from cooking or washing. Insufficient ventilation is the main cause, for example, due to double-glazing, blocking of flues and air bricks, or incorrect installation of roofing underlay.

Condensation occurs mostly in winter, but can appear throughout all seasons depending on your home and climate. It might first be noticed when water droplets form on hard surfaces, or mold appears on absorbent finishes. 

What is known as ‘interstitial’ condensation occurs within the building materials and elements. For example, if a wall is covered with an impermeable barrier or render that doesn’t allow moisture to pass through the wall naturally.

If the condensation problem you have seems to be more than one you can solve yourself, it will be worth employing an independent chartered surveyor or consultant (not a contractor with a vested commercial interest); they can carry out a more detailed investigation if required.

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After beginning his career as a chartered surveyor, Douglas soon specialised in building conservation. In 2000 he joined the Society for the Protection of Ancient Buildings (SPAB) where he now holds the position of technical and research director.

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