'Fix it now or pay later' – experts reveal the 8 hidden risks of window condensation (and what causes it)

As the seasons change, you'll likely notice the return of window condensation. But what causes it, and why do we need to deal with it?

If you've ever researched what condensation is, you'll know it's moisture that forms when warm, damp air hits a colder surface. While it can also occur on walls, window condensation is easier to spot because of its 'steamed up' appearance, which affects our view outside.

Ignoring window condensation can lead to a variety of long-term problems, such as damp and mould, which is why it's important to nip it in the bud. We asked the experts what causes it and why you need to eradicate it from your home.

What causes window condensation?

If you want to stop window condensation in your home, you'll need to understand the following causes:

1. Lack of ventilation

Homes need constant ventilation and air flow to prevent moisture build-up.

Every time we breathe in a room, moisture is released into the air, and window condensation can occur if there is insufficient natural or mechanical ventilation, such as an MVHR system.

2. Single-glazed windows

Window condensation is an issue I'm dealing with myself having single-glazed windows throughout my property.

Without the best dehumidifier in action overnight in my bedroom, cold spells outside always mean I wake up to condensation on my windows, leaving me reaching for the best window vac.

The single panes of glass do not offer enough thermal efficiency to deal with the room's humidity in relation to the outside drop in temperature.

3. Extra humidity

Window condensation can also occur when humidity exceeds 40% during winter months, but devices such as dehumidifiers can help bring it back to normal levels.

One contributing factor that can increase humidity during the wet and colder months, is the need to dry laundry inside. Plus, with more people indoors during the winter, it naturally increases moisture from the home's inhabitants.

Why you need to fix window condensation

Left to linger, window condensation can end up being a costly exercise – both in terms of your wallet and your health.

“Condensation itself is a minor issue," says Andy Simms, building expert at Mybuilder.com. "However, it's better to fix it sooner rather than later to avoid bigger problems that could cost money to repair."

1. Damp: “Window condensation is one of the biggest causes of damp in homes, and more often than not, will eventually lead to the growth of mould," says Jo Trotman.

2. Window frame damage: This can be caused by leaving water to pool on the frames which will rot the wood.

3. Sill damage: Similarly, window condensation, which streams down windows and pools on sills, can eventually lead to the degradation of them.

4. Peeling paint: Water will eventually seep into the paint, meaning the protective layer will come off and expose the wood.

5. Damaged plaster: Over time, damp will find its way into the walls around the window frame and could result in crumbling plaster.

6. Damage to window treatments: Curtains and blinds can both be affected by damp and mould, which will then need to be replaced.

7. Pests: From silverfish to cockroaches, the dampness can result in a long list of unwanted pests, according to Andy Simms.

8. Health risks: It's not just your property that's at risk; your family could be too.

"Leaving window condensation untreated will result in long-term damage to your property, as well as the people living there," warns Andy. "Black mould, formed after prolonged condensation, causes respiratory issues, especially in people with asthma or with allergies."

“Over-exposure to mould has some serious health implications," confirms Jo Trotman, marketing manager at The Residence Collection. "It can even cause serious health conditions such as bronchitis, or pneumonia.”

Jo Trotman

Jo Trotman has worked as a Marketing Manager at The Residence Collection, and sister company Window Widgets, for over three years, becoming well versed in the importance of installing the right windows in your home.

Andy Simms

With almost a decade of experience on the front line in construction as a multi-trader, Andy has a vast amount of knowledge and expertise in both homebuilding and maintenance.

Why is window condensation more of a problem in the autumn and winter?

"Condensation occurs when warm, humid air inside your home comes into contact with a cold surface like a window," explains Andy Simms. "This is very common in the colder months such as December and January, where temperature differences between the inside and outside of the house are greatest."

“As the seasons change, homeowners also begin using their heating systems to combat the winter chill, raising indoor temperatures and creating a more humid environment within the home," says Jo Trotman. "This combination elevates the risk of window condensation.”

FAQs

Can you get condensation on double-glazed windows?

Although the risks of window condensation on double-glazed units are less, it can still happen if there is poor insulation or a lack of ventilation. Condensation inside double-glazed windows is another common issue and happens when the panes have failed.

What is a window condensation absorber?

Window condensation absorbers are also known as moisture traps. They are small units filled with absorbent crystals that suck up moisture in the air and can be a cheap, effective solution.

If you're interested in giving one a go, the Kontrol Moisture Trap (available on Amazon) is a good option, thanks to its slimline, unobtrusive design.

There are many reasons why you shouldn’t ignore window condensation – not only can it cause costly damage to your home, but it can also lead to long-term health issues.

If you found this helpful, you may also want to read our guides on how to fix condensation in a loft and how to stop condensation on walls next.