Why condensation forms on windows—and how to get rid of it quickly

Britain’s cold snaps almost always prompt the same question among homeowners: Why is my house Windows Suddenly dripping water? As outside temperatures drop and indoor temperatures rise, warm, moist indoor air encounters cold window panes, and condensation forms as a result. While a small amount of moisture is not uncommon on a cold morning, continued condensation can cause trouble, damaging the frame and increasing the risk of mold.

This guide explains why condensation is exacerbated in winter, its impact on windows and the most effective ways to remove and prevent it.

Is there condensation on your windows? It might be time to look for alternatives

If condensation persists on the inside of your windows, it may be a sign that your windows need to be replaced. You can get a range of free quotes from leading companies using the comparison tool below UK window installers.

What is window condensation and why does it happen in winter?

Condensation forms when warm, moist air comes into contact with cold surfaces. Moisture in the air condenses into liquid water, forming droplets on the inside of the window.

The cold snap made the problem worse. Windows lose heat quickly, indoor heating increases humidity, and most people close their homes tightly to keep warm. Everyday activities such as showering, cooking, boiling the kettle, drying clothes indoors and even breathing add liters of moisture to the air.

When your windows are the coldest spots in the room, the moisture has to settle somewhere.

Is condensation bad for your windows?

A small amount of condensation in the morning is fairly normal, especially in older homes or rooms with high humidity. But continued moisture can cause problems:

There’s also condensation that points to a deeper problem: moisture retention between Double glazed windows. This usually indicates a seal failure, meaning insulating gas has escaped. In this case, the affected sealing unit will need to be replaced.

Types of condensation and what they tell you

Not all condensation is the same, and knowing the type you’re dealing with can help you pinpoint the cause and choose the right solution. Some forms are harmless and simply reflect how modern glass works, while others may indicate a problem with part of your window system. Here’s how to tell the difference.

Condensation inside windows

This is the most common type and is almost always caused by excessive indoor humidity. It can usually be fixed with better ventilation and small lifestyle changes.

Condensation outside the window

This phenomenon occurs on modern, energy-efficient double or triple glazing on cold, clear mornings. This indicates that the windows effectively retain heat from the interior and will usually clear it on their own.

condensation between glass

If you notice mist inside the seal, double glazing It may have failed. The only solution is to replace the affected unit as the seal cannot be repaired.

Quick Fix: How to Get Rid of Condensation Quickly

Before we delve into specific techniques, know that the following quick fixes for window condensation are all about removing moisture that has already built up and preventing new moisture from settling on your windows. These steps alone won’t solve the underlying moisture problem, but they can have an immediate effect, especially during cold spells.

Long-term solution to stop condensation returning

While quick fixes can resolve the symptoms, long-term solutions can address the root cause: excessive humidity, cold surfaces, and poor airflow. These changes are more effective at permanently preventing condensation and can significantly improve comfort, indoor air quality, and the lifespan of your windows.

Improve ventilation

Even in the winter, keeping trickle vents open will ensure a steady flow of fresh air without creating noticeable drafts. Many homeowners keep them closed to keep them warm, but this often traps moist air inside. Improving airflow also means opening windows for short periods of time throughout the day, or considering a whole-house system like positive pressure ventilation (PIV), which gently pushes fresh, filtered air into the house to reduce moisture buildup.

Reduce indoor humidity

Reducing the amount of moisture produced in your home is one of the most effective long-term strategies. If possible, avoid drying clothes indoors, or if necessary, make sure the room is well ventilated. one Dehumidifier It can also help manage humidity levels, especially in bedrooms, kitchens and utility spaces where damp can build up quickly. Keeping your home at a consistent temperature prevents cold surfaces from forming, which reduces moisture buildup.

Upgrade your glass

Older single-pane windows are prone to condensation because the glass inside becomes very cold. Class A double glazing keeps the inner glass warm and reduces condensation. If you have installed double glazing but notice fog forming between the panes, replacing the sealing unit is the most effective solution.

Improve insulation and airflow

A well-insulated home maintains a more stable temperature, reducing the amount of moisture settling on cold surfaces. But it’s important to combine insulation with adequate ventilation to prevent moisture from becoming trapped indoors.

When condensation indicates a bigger problem

If you notice black mold around your window frames, damp spots on your walls, or a persistent musty smell, condensation may be part of a wider problem rather than a simple winter nuisance. While everyday condensation is caused by excessive indoor humidity, more serious problems can stem from structural failures that allow moisture to enter or become trapped in your home.

Chronic dampness can be caused by leaking gutters, cracked stucco, poor window frame seals or damaged prongs that allow rainwater to seep into exterior walls. Older homes with solid walls or insufficient ventilation are particularly susceptible because there are fewer ways for moisture to escape. In these cases, simply increasing ventilation may not solve the underlying problem.

It is also important to distinguish between surface condensation and rising or penetrating moisture. Rising moisture often appears as low tide marks on interior walls, while penetrating moisture appears as isolated patches that worsen after rain. If you’re unsure, a qualified surveyor or damp expert can assess the source of the problem and recommend the correct treatment.

Continued growth of mold, especially if it reappears after cleaning, is a sign that you may need professional advice. Mold can affect indoor air quality, and in severe cases, certain structural elements may need to be repaired or replaced.