How To Remove Condensation In Double Glazing
Condensation in double glazing is a common concern for homeowners and property professionals alike. If you’ve noticed misting on your windows, water droplets forming on the glass, or moisture trapped between panes, you may be wondering what’s causing it, and more importantly, how to remove it.
In this blog, we’ll explain why condensation forms, the difference between internal and external condensation, how to remove it, and when it might be time to repair or replace your double glazed unit.
Why Does Condensation Form on Double Glazing?
Condensation occurs when warm, moisture-heavy air meets a cold surface. As the air cools, it can no longer hold the same amount of moisture, which causes water droplets to form.
Double glazing is designed to reduce heat transfer, but condensation can still appear under certain conditions, particularly during colder months when there is a bigger temperature difference between indoors and outdoors.
However, not all condensation is the same. Understanding where it appears is key to knowing how to deal with it.
Types of Condensation in Double Glazed Windows
1. Condensation on the Inside of the Glass
This is the most common type and is usually caused by high humidity levels inside the property. Everyday activities such as cooking, showering, drying clothes indoors and even breathing release moisture into the air.
If ventilation is limited, that moisture settles on colder surfaces – including your windows.
2. Condensation on the Outside of the Glass
External condensation can form on the outer pane of high-performance double glazing. This is actually a sign your windows are insulating well. The outer pane remains cooler because heat isn’t escaping from inside the home.
This type of condensation usually clears naturally as temperatures rise during the day.
3. Condensation Between the Panes
Moisture trapped between the two panes of glass is a different issue. This usually indicates a failed seal within the double glazed unit, allowing moisture to enter the cavity.
When this happens, the unit is often referred to as “blown” and will not clear on its own.
How to Fix Condensation on the Inside of Double Glazing
If condensation is forming on the inside surface of your windows, the issue is likely indoor humidity rather than a fault with the glazing itself. Here are effective ways to reduce and remove it:
Improve Ventilation
- Open windows regularly to allow airflow
- Use trickle vents if installed
- Keep internal doors open where possible
- Use extractor fans in kitchens and bathrooms
Improved air circulation helps reduce moisture build-up.
Use a Dehumidifier
A dehumidifier can significantly reduce indoor humidity levels, especially during winter when windows are kept closed. Lower humidity means less condensation forming on glass surfaces.
Wipe Down Windows
Regularly wiping condensation away prevents water from pooling on window sills and causing potential mould growth or damage.
Maintain Consistent Heating
Keeping a steady indoor temperature reduces the temperature difference between air and glass, minimising condensation risk.
How to Remove Condensation on the Outside of Double Glazing
External condensation does not require treatment. It usually forms overnight when temperatures drop and clears naturally as the sun rises. External condensation is often a positive sign that your double glazing is performing efficiently by retaining heat inside the property. If it’s temporary and appears only in the early morning, there’s no cause for concern.
How to Remove Condensation Between Double Glazing Panes
Condensation trapped inside the sealed unit is more serious. Unfortunately, once the seal has failed, the moisture cannot simply be wiped away. The sealed cavity is designed to be airtight, and once compromised, its insulating properties are reduced.
Your options include:
Replace the Sealed Unit
In many cases, you can replace just the glass unit without replacing the entire frame – provided the frame is still in good condition, which is often a more cost-effective solution.
Full Window Replacement
If the frame is also damaged, warped or outdated, replacing the entire window may be the better long-term investment for your home.
Can You Fix a Blown Double Glazing Unit Yourself?
There are temporary DIY solutions advertised, such as drilling small holes into the unit to release moisture. However, these methods can cause further damage, may void warranties and they do not restore insulation performance. For long-term performance and safety, it’s always recommended to consult a glazing professional.
How to Prevent Condensation in the Future
While some condensation is unavoidable, particularly during colder months, there are steps you can take to minimise it.
Control Indoor Humidity
- Avoid drying clothes indoors where possible
- Use lids on pans when cooking
- Ventilate rooms after showering
- Keep extractor fans running for 10–15 minutes after use
Improve Airflow
Modern homes are often well insulated, which is excellent for energy efficiency but can trap moisture. Ensuring regular airflow prevents humidity from building up.
Upgrade Older Windows
If your windows are more than 20 years old, upgrading to modern high-performance double glazing can improve thermal efficiency and reduce condensation issues.
Modern units feature improved spacer bars, enhanced seal technology and better insulation performance.
When Should You Be Concerned?
Condensation on the inside or outside of your windows is usually manageable. However, you should investigate further if you notice:
- Persistent condensation between panes
- Visible water droplets inside the cavity
- Misting that never clears
- Draughts around frames
- Signs of mould growth
These could indicate seal failure or reduced window performance.
Is Condensation a Sign You Need New Windows?
Not always. Internal condensation is typically a ventilation issue, not a glazing fault. External condensation can actually indicate strong thermal performance. However, condensation between panes usually means the sealed unit has failed and may require replacement.
Understanding the difference helps you avoid unnecessary costs while addressing genuine issues effectively.
Final Thoughts
Condensation in double glazing can be frustrating, but in many cases it’s completely normal and manageable. Identifying whether it’s internal, external or between panes is the key to deciding what action to take.
Improving ventilation, controlling humidity and maintaining consistent heating will help reduce everyday condensation. If moisture is trapped inside the sealed unit, professional repair or replacement may be required.
By understanding the cause and responding appropriately, you can maintain the efficiency, appearance and performance of your double glazed windows for years to come.
At UKO Glass, we’re here to help you resolve condensation issues quickly and effectively. Whether you need expert advice, a replacement sealed unit, or a full glazing solution, our team can provide high-performance products tailored to your project. Get in touch today on 01422 861116 and let’s restore clarity, efficiency and long-term performance to your windows.