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3 reasons why you have condensation forming on the inside of your windows (and how to stop it) according to experts

You probably do this every day

A bathroom window with toiletries displayed on the window sill
(Image credit: Future PLC/Jamie Mason)

I don’t know about you, but I am frequently greeted by drips of condensation running down the inside of my windows every morning. And for me, I like to understand what causes a problem before I solve it, so I asked the experts; ‘what causes condensation on the inside of windows?’

Condensation is a common winter problem, and if left untreated, it can quickly result in damp and mould inside your home. We all want to know how to stop condensation on windows, but to do so, it’s essential to understand what causes condensation outside windows and inside.

1. Everyday humidity

‘Condensation can be found anywhere in the home where moisture is heated and condenses onto cooler surfaces. This means it's common in bedrooms, bathrooms and kitchens. Activities like showering, cooking or drying clothes can lead to water vapour cooling against cold surfaces, including windows,’ explains Dr Jonathan Kirby, Mould Expert at Dryzone.

‘However, issues can arise if this moisture is left to condense on cool surfaces. Condensation is one of the most common damp problems and can ruin painted or plastered walls, furniture and plush toys.’

White bathroom with a bath with a shower over it, and a floral shower curtain surrounded by plants

(Image credit: Future PLC/Dan Duchars)

Breathing out as we sleep is a contributing factor to why condensation forms on windows overnight, too. Every day, humidity is hard to avoid, but there are a few things you can do to reduce it. You should avoid drying clothes on radiators and invest in one of the best dehumidifiers instead to speed up the drying process.

2. Single glazing

Another factor contributing to condensation forming on the inside of windows is whether you have single-glazing or not. Not only is single glazing less energy efficient, but it is also cooler to touch than double glazing, increasing the chance of condensation forming when warm air hits it. Of course, condensation can form on double-glazed windows, too, and you should take time to ventilate the room or use a dehumidifier.

A large window with a window seat and cushions

(Image credit: Future PLC/Joanna Henderson)

‘Single-glazed windows are particularly prone to condensation because they lose heat quickly, creating a colder surface for moisture to cling to,’ confirms Yvonne Keal, product expert at Hillarys.

3. Your home is too 'air tight'

‘Homes that are very airtight, while energy-efficient, can suffer from condensation because moisture has nowhere to go,’ explains Yvonne.

a child's room with a pink painted ceiling, a Velux window and a scalloped pelmet

(Image credit: Future PLC /James French)

Ventilation is key to keeping your home condensation-free. While it may be tempting to trap as much heat in your home as possible, it can be helpful to ‘air’ your home when necessary.

The German principle of Stoßlüften is the practice of opening all the doors and windows in your home for 15 minutes in the morning to let the moist, warm air out, and let cool, dry air in.

You can also use a dehumidifier to suck excess moisture out of the air, so you don’t lose any heat.

How to stop condensation

A lot of the time, condensation is inevitable, but understanding the different factors that cause it can help with your plan of attack to get rid of condensation.

Kezia Reynolds
News Writer

Kezia Reynolds joined the Ideal Home team as News Writer in September 2024. After graduating from City, University of London in 2022 with a bachelor’s degree in journalism, Kezia kicked off her career spending two years working on women’s weekly magazines. She is always on the lookout for the latest home news, finding you the best deals and trends - so you don’t miss a thing!