Condensation on Windows: What It Means and How to Reduce It
Updated: Sep 17
We love autumn for the pumpkin spice and changing leaves - but it also brings a real pain in the neck for many Scottish homeowners: condensation. Creeping in with the colder weather, it can leave your windows dripping by morning. Read on to find out what causes it - and what you can do to fix it.
Waking up to wet windows when the temperature drops? You’re definitely not the only one.
Condensation is a common sight in Scottish homes through autumn and winter, when warm air inside meets colder glass. But while a little condensation can be perfectly normal, where it appears on your window can tell you quite a lot about what’s causing it.
Condensation on the inside of your windows, moisture on the outside and misting trapped between the panes all mean different things. Some can be improved with a few simple changes at home, while others can be a sign that your double glazing needs a closer look.
Here’s how to tell the difference.
What Causes Condensation on Windows?
There’s always some moisture in the air inside our homes. Everyday things like cooking, showering, drying clothes and even breathing all add to it.
When that warm, moisture-filled air comes into contact with a colder surface, such as a window, it cools down. If the glass is cold enough, the moisture in the air turns into tiny droplets of water.
That’s condensation.
You’ll usually notice it more as the weather gets colder, particularly first thing in the morning or in rooms where there tends to be more moisture in the air, such as bedrooms, kitchens and bathrooms.
But before you start worrying about your windows, the first thing to check is where the condensation actually is.
Where Is the Condensation on Your Window?
The easiest way to work out what might be causing the problem is to look at which side of the glass is wet.
Condensation on the Inside of Your Windows
If you can wipe the moisture away from the glass inside your home, the condensation is usually being caused by moisture in the indoor air meeting the colder window surface.
This is especially common in bedrooms overnight, after showering, while cooking or when clothes are being dried indoors.
A small amount from time to time isn’t unusual, particularly during colder weather. But if your windows are regularly soaking wet, water is running onto the sill or you’re noticing mould beginning to appear around the window, it’s worth looking at the moisture and ventilation levels in the room.
Later in this guide, we’ll look at some simple ways to reduce it.
Condensation on the Outside of Your Windows
Opened the curtains to find condensation on the outside of the glass?
It can look a little strange, but it’s usually nothing to worry about.
External condensation happens when the outside surface of the glass becomes colder than the air around it, causing moisture in the outdoor air to settle on the pane.
It can sometimes be more noticeable on well-insulated modern glazing because less heat from inside the home is reaching the outer pane. That just means your windows are working as they should - keeping the heat in and the cold out.
In most cases, it will disappear naturally as the outside temperature lifts throughout the day.
Condensation Between the Panes of Double Glazing
This one is different.
If the glass looks misty or cloudy but you can’t wipe the moisture away from either side, the condensation is likely to be inside the sealed double-glazed unit.
Double glazing is designed with a sealed space between the panes. If that seal begins to fail, moisture can find its way inside and you may start to notice misting, droplets or a cloudy appearance between the glass.
Unlike condensation on the room-facing surface, this isn’t something that better ventilation will solve.
It doesn’t automatically mean every window in your home needs replacing, but the affected unit should be checked so you can understand what has failed and what your options are. If this is what you’re seeing at home, we’ve put together a more detailed guide to condensation between double glazing, including what it means, whether it can be repaired and when replacement might make more sense.
How to Reduce Condensation on the Inside of Your Windows
If the condensation is on the glass inside of your home, the good news is there are a few simple things you can try before worrying about the windows themselves.
The aim is to reduce the amount of moisture building up inside your home and give it somewhere to escape.
Use Your Extractor Fans
Kitchens and bathrooms create a lot of moisture in a short space of time, so use extractor fans while you’re cooking or showering and leave them running for a little while afterwards.
Keeping bathroom and kitchen doors closed while there’s lots of steam around can also help stop that moisture travelling into the rest of the house.
Keep Trickle Vents Open
If your windows have trickle vents, they’re there for a reason.
Keeping them open allows a small amount of background ventilation without having to leave a window wide open on a cold Scottish morning.
It might be tempting to close every vent as soon as the temperature drops, but your home still needs ventilation through winter.
Give Your Home a Little Fresh Air
Opening windows for a short period can help let moisture out and bring fresh air in.
You don’t need to have them open all day. A short burst of ventilation can be particularly useful after showering, cooking or first thing in the morning if a bedroom has become humid overnight.
We know that telling anyone in Scotland to just dry everything outside from October onwards isn’t especially helpful. If you do need to dry washing indoors, try to keep the room ventilated and avoid drying clothes directly against radiators where possible.
A tumble dryer vented correctly to the outside, or a dehumidifier where appropriate, can also help manage the extra moisture.
Keep Your Home Consistently Heated
Very cold surfaces make it easier for condensation to form.
Keeping your home at a reasonably consistent temperature can help reduce the contrast between warm, moist indoor air and cold glass. That doesn’t mean turning the heating up unnecessarily. It’s more about avoiding rooms becoming extremely cold for long periods and then suddenly filling them with warm, humid air.
Wipe Away Heavy Condensation
If water is regularly collecting on the glass or window sill, wipe it away rather than leaving it sitting there. This won’t fix the cause of the condensation, but it can help prevent moisture from sitting around frames, seals and surrounding decoration, where persistent damp can eventually cause problems.
If you’re doing all of this and your windows are still regularly covered in heavy condensation, it may be worth looking more closely at what else is contributing to it.
Will New Windows Stop Condensation?
Not always - and this is where it’s important to look at what’s actually causing the condensation in the first place.
If moisture is forming on the inside of your windows because there’s a lot of humidity in the home or not enough ventilation, replacing the windows alone won’t remove that moisture.
New windows can, however, make a difference where older windows are cold, draughty or no longer performing as well as they should.
Modern double glazing is designed to keep the internal surface of the glass warmer than older, less efficient glazing. A warmer surface gives moisture in the air less opportunity to condense on the glass, while better-performing frames and seals can also help make the room feel more comfortable.
That said, even the best windows still need to work alongside good ventilation.
In fact, if you replace older draughty windows with much better sealed ones, managing ventilation becomes even more important because some of the uncontrolled airflow that was previously moving through gaps around the windows has been removed.
So if condensation is one of the reasons you’re thinking about replacing your windows, it’s worth looking at the whole picture rather than assuming new windows will make it disappear overnight.
When Should You Have Your Windows Checked?
A little condensation on the room-facing side of the glass during cold weather doesn’t necessarily mean there’s anything wrong with your windows.
There are, however, a few signs that are worth investigating.
You may want to have your windows checked if:
condensation or misting is trapped between the panes of glass
you can feel noticeable draughts around the window
seals appear damaged, loose or deteriorated
windows are becoming difficult to open, close or lock
frames are showing signs of damage or deterioration
rooms feel particularly cold around older windows
your windows are simply getting older and you’re unsure how well they’re still performing
Sometimes the answer might be a smaller repair or replacement sealed unit. In other cases, particularly with older windows showing several signs of wear, it can make more sense to look at replacing the complete window.
A good starting point is simply understanding what’s causing the problem and what options are available before deciding whether anything needs replaced.
Is condensation on the inside of your window normal?
A small amount of condensation on the inside of your windows can be normal during colder weather, particularly first thing in the morning or in rooms such as bedrooms, kitchens and bathrooms.
If the windows are regularly soaking wet, however, it’s worth looking at humidity, heating and ventilation in the room rather than simply accepting it as part of winter.
Why are my bedroom windows wet every morning?
We create moisture while we sleep simply by breathing, and bedrooms are often kept cooler overnight with doors and windows closed.
That combination can mean moisture builds up in the room and then condenses on the cold glass.
Keeping trickle vents open, allowing some fresh air into the room and avoiding letting the bedroom become extremely cold can all help.
Is condensation on the outside of new windows normal?
Yes, it can be.
External condensation can happen when the outer pane of glass becomes colder than the outside air around it. It can actually be more noticeable with thermally efficient glazing because less heat from inside your home is passing through to warm the outer pane. It will usually clear naturally as the temperature changes.
Can condensation between double glazing be repaired?
If moisture is trapped between the panes, it usually means the seal within the double-glazed unit has failed.
Depending on the condition and age of the window, it may be possible to replace the sealed glass unit without replacing the entire frame.
If the window is older or has other issues such as damaged frames, draughts or problems opening and closing, it may be worth considering whether replacing the complete window makes more sense.
Will replacing my windows stop condensation?
It depends on what is causing it. Better-performing double glazing can provide a warmer internal glass surface and reduce draughts, which may help in some homes. But if the main problem is high humidity or poor ventilation, replacing the windows alone won’t remove the moisture from the air.
The best approach is to understand the cause first.
Thinking About Replacing Your Windows?
If your condensation is trapped between the panes, your existing windows feel draughty or they’re simply no longer performing as well as you’d like, it may be time to look at your options.
At Doorquay, we supply and fit replacement windows for homes across Dundee, Angus, Fife and Perthshire, with uPVC, aluminium and composite window options available.
Our team can help you look at what’s currently fitted, talk through what you’d like to improve and explore the options that suit your home - without assuming that replacement is automatically the answer.
If you’re specifically looking for a local installer, you can also find out more about our window fitters in Dundee and how we approach measuring, supplying and fitting new windows.
Not Sure Whether Your Windows Need Replacing?
If you’re seeing condensation between the panes, feeling draughts around older frames or your windows simply aren’t performing as well as they used to, we can help you work out what your options are.
At Doorquay, we supply and fit replacement windows across Dundee, Angus, Fife and Perthshire. We’ll look at what’s currently fitted, talk through what you’d like to improve and help you decide what makes sense for your home.
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