Waking up to condensation on windows is one of the most common problems in UK homes, especially from October to March. Streaming glass, puddles on the sill and black spots on the seals are not just annoying. Left alone, constant condensation can rot timber, stain plaster and encourage mould around the frame.
The good news is that most window condensation can be reduced with a few simple habits and, where needed, small repairs such as fitting trickle vents or replacing a failed glass unit. This guide explains why condensation forms, where it appears, and the practical steps homeowners in Berkshire and Surrey can take to stop it.
What Causes Condensation on Windows?
Condensation forms when warm, moist air inside your home touches a colder surface. The air cools, it can no longer hold all of its water vapour, and that moisture turns into droplets on the coldest surface in the room. In most homes that surface is the window glass or frame.
Everyday activities add moisture to the air all the time: cooking, showering, boiling the kettle, drying clothes indoors and even breathing while you sleep. When that moisture has nowhere to escape, it settles on your windows.
Inside, Outside or Between the Panes: What It Means
Condensation on the inside of the glass
This is the most common type. It usually points to high humidity and poor ventilation in the room, often in bedrooms, kitchens and bathrooms. It is normally fixed with better ventilation and moisture control rather than new windows.
Condensation between the panes
If the moisture is trapped inside a double glazed unit and you cannot wipe it away, the seal on the sealed unit has failed. This is often called misted double glazing. The glass will not clear on its own, but you rarely need a new window. Read our guide on why windows go cloudy, or see our misted double glazing repair in Berkshire service.
Condensation on the outside of the glass
Light condensation on the outside on a cold morning is usually a good sign. It means your double glazing is keeping heat inside the house, so the outer pane stays cold. It clears as the day warms up.
7 Common Causes of Condensation on Windows
- Poor ventilation: windows kept shut all winter and no trickle vents to let moist air out.
- Drying clothes indoors: a rack of wet washing releases a large amount of water vapour into the room.
- Cooking and bathing without extractor fans: steam spreads through the house and settles on the coldest glass.
- Cold, uneven heating: rooms that are rarely heated have colder windows, so condensation forms more easily.
- Old or single glazing: older glass and frames are colder on the room side.
- Failed seals and gaskets: worn window seals create cold spots and draughts around the frame.
- Furniture and curtains against the glass: heavy curtains trap cold, damp air against the window overnight.
How to Stop Condensation on Windows: Quick Fixes
Start with these low-cost habits. Many homes see a big difference within a week or two.
- Open bedroom windows for 10 to 15 minutes each morning to let moist air out.
- Use the extractor fan and keep the door closed when cooking or showering.
- Put lids on pans and dry clothes outside or in a vented tumble dryer where possible.
- Keep a low, steady background heat rather than short bursts of high heat.
- Wipe the glass and sills dry each morning so water does not soak into seals and frames.
- Pull curtains and furniture a little away from windows to let air move.
- Consider a dehumidifier for rooms that stay damp.
Long-Term Solutions for Window Condensation
Fit trickle vents
Trickle vents are small vents in the top of the window frame that let a gentle flow of fresh air in, even when the window is closed. They are one of the most effective ways to reduce condensation on windows without losing much heat. We fit them to existing UPVC windows through our trickle vent installation service, and also offer trickle vent installation in Surrey.
Replace failed or misted glass units
If your double glazing has misted between the panes, the unit has lost its insulating gas and is colder than it should be. Replacing only the sealed unit keeps your existing frame and restores the glass performance. See our double glazing repair in Surrey and Berkshire services.
Repair worn seals and draughts
Perished gaskets and badly adjusted sashes let cold air in around the frame, creating cold spots where condensation and mould gather. Replacing seals and adjusting hinges and locks often solves this. Our guide on draughty doors covers the same problem for doors.
Is Window Condensation Harmful?
Occasional condensation is normal, but if it happens every day it can lead to damp and black mould on frames, walls and curtains. Mould can affect health, especially for children, older people and anyone with asthma or a lung condition. The government guidance on understanding the health risks of damp and mould explains this in more detail. For advice on keeping homes warm and efficient, the Energy Saving Trust guide to windows and doors is also a useful resource.
Window Condensation Help in Berkshire and Surrey
If condensation on your windows keeps coming back, our local engineers can check your windows, fit trickle vents, replace misted units and repair worn seals, usually in a single visit. We repair what has failed rather than selling you new windows.
- Window repair across Berkshire: window repair Berkshire
- Window repair across Surrey: window repair Surrey
- Free, no-obligation quotes: contact us or call 07951 152986
Frequently Asked Questions
Why do I get condensation on my windows every morning?
Overnight, moisture from breathing builds up in a closed bedroom and the window glass is at its coldest. Opening the window or trickle vents for a short time each morning and keeping a little background heat usually reduces it.
Does double glazing stop condensation?
Double glazing keeps the room-side glass warmer, so condensation forms less often. But if the room is very humid and poorly ventilated, you can still get condensation on the inside of double glazed windows.
Is condensation between the panes fixable?
Yes. Moisture between the panes means the sealed unit has failed. We replace the glass unit and keep your existing frame, which is much cheaper than a full new window.
Do trickle vents really help with condensation?
Yes. Trickle vents let a small, constant amount of fresh air in so moist air can escape, which is one of the simplest ways to cut down condensation on windows.
