What Causes Condensation On Double-Glazed Windows, And How To Prevent It

Double-glazed windows are designed for superior insulation with a gas or air-filled space between two glass panes, reducing heat transfer, ensuring your home stays warmer in winter and cooler in summer.

While double glazing helps reduce condensation by keeping the internal pane of glass closer to room temperature, it is still possible to experience condensation within these units. This can indicate ageing windows or, in some cases, installation issues.

Let’s delve into what causes condensation on double-glazed windows, and explore solutions to keep your home comfortable and efficient.

Understanding Condensation

Condensation occurs when warm, moist air comes into contact with a cooler surface, causing the moisture in the air to turn into liquid droplets. In the home, this usually occurs on windows, where significant temperature differences between indoor and outdoor environments are present.

Common signs of condensation include water droplets on the glass, a foggy or misty appearance, and even water pooling at the bottom of the window frame.

Why Is Condensation An Issue?

Over time, condensation on double-glazing can lead to issues such as mould growth, deterioration of window frames, and reduced effectiveness of the insulation, ultimately compromising the energy efficiency and comfort of your home.

Beyond the visual impact, mould can also pose serious health risks, including respiratory problems, allergies, and asthma, and is particularly dangerous to vulnerable individuals such as children, the elderly, and those with pre-existing health conditions.

What Causes Condensation On Double Glazed-Windows​

Understanding the causes of condensation is essential for addressing and preventing it. Here are the primary factors contributing to condensation on double-glazed windows:

Indoor Humidity

High indoor humidity is a significant contributor to condensation. Everyday activities such as cooking, showering, and drying clothes indoors increase humidity levels, leading to condensation.

Temperature Differences

Condensation occurs when there is a significant temperature difference between the inside and outside of the home. During colder months, the warm indoor air meets the cold window, resulting in condensation.

Poor Ventilation

Proper ventilation is crucial in preventing condensation. Poorly ventilated areas can trap moisture, increasing the likelihood of condensation on windows.

Seal Failure

The seal between the two panes of glass can degrade over time, leading to condensation between panes. This seal failure is the primary cause of misting or fogging inside double glazed units.

Saturated Dessicant

Some double glazed windows have spacers filled with desiccant materials that absorb moisture. If these desiccants become saturated, they can no longer prevent condensation from forming inside the windows.

Lifestyle Factors

Certain lifestyle habits can influence the amount of condensation in your home. Drying clothes indoors, lack of window coverings, and insufficient heating can all contribute to higher humidity levels and condensation.

Condensation In Between Double-Glazed Window Panes

Also known as misting, condensation that occurs in between the panes of a double glazed window can affect the clarity of the glass, and indicate a failure in the window’s insulation properties.

Should You Repair Or Replace?

The most common causes of misting in double-glazed windows are seal failure, manufacturing defects with low-quality products, or poor installation. For high-quality windows with isolated seal failures, repairing the seals is often the most effective solution. This approach maintains the integrity and aesthetics of the original installation.

However, if you have newer but poorly made double-glazed windows with multiple failed units and damaged frames, replacement may be the better option. Upgrading to windows with advanced weather-tight seals and innovative thermal breaks will not only resolve the misting issue but also provide enhanced thermal efficiency and longevity.

Seeking Professional Advice

If misting is occurring, it is crucial to seek help from a trusted and experienced professional. They can assess the condition of your windows and recommend the best course of action, whether it be repair or replacement, to ensure your windows remain clear, efficient, and aesthetically pleasing.

condensation misting

How to Prevent Condensation on Double-Glazed Windows

Now that we’ve discussed what causes condensation on double-glazed windows, let’s break down the ways you can solve the issue. Not only does condensation obstruct your view, but it can also lead to mould growth and damage to window frames. Thankfully, there are several effective strategies to prevent condensation and maintain the beauty and functionality of your windows. Here’s a comprehensive guide to help you keep your double glazed windows clear and your home environment comfortable.

1. Control Indoor Humidity

    • Use Dehumidifiers: Dehumidifiers extract moisture from the air, significantly lowering indoor humidity levels and reducing the chance of condensation on your windows. They are particularly effective in areas with high moisture such as laundry rooms.

    • Utilise Exhaust Fans: Install and regularly use exhaust fans in kitchens and bathrooms where moisture is generated, as they help to expel humid air outside.

    • Avoid Drying Clothes Indoors: Drying clothes indoors can release a lot of moisture into the air. Whenever possible use a dryer or an outdoor clothesline instead, this will keep indoor air drier and your windows free of condensation.

2. Improve Ventilation

    • Open Windows Regularly: Allow fresh air to circulate by opening windows daily, even if just for a short period.

    • Choose Tilt and Turn Windows: By choosing windows that tilt and lock into position, this lets in a constant flow of fresh air into your home, helping to prevent moisture buildup without compromising security or energy efficiency.

3. Regular Maintenance

    • Inspect Window Seals: Check for any signs of wear and tear on the seals, such as cracks or gaps. Damaged seals can allow moisture to seep in between the panes.

    • Timely Repairs: Address any seal failures promptly to prevent further issues, such as water damage or mould growth. Timely repairs from experienced professionals can extend the life of your windows and maintain their insulating properties.

    • Clean Windows: Keep your windows clean to identify any potential problems early, such as dirt buildup that can mask seal damage. 

The Importance of Quality Double Glazing

Investing in high-quality double-glazed windows from a reputable and experienced provider is the best way to ensure your home is free from excess condensation. Here’s why:

    • Durable Seals: Quality windows are less likely to experience seal failure, a common cause of condensation. Durable seals prevent moisture from seeping between the panes, maintaining the insulating properties of the windows and ensuring long-term performance.

    • Better Insulation: High-quality double glazing effectively manages indoor humidity and temperature, reducing the likelihood of condensation.

    • Low-E glass: Quality windows that feature Low-E (low-emissivity) glass provide an additional layer of protection against condensation. Low-E glass has a special coating that reflects heat back into your home, helping to maintain a consistent indoor temperature. Learn more about Low-E glass here.

worker measuring for a window installation

When to Seek Professional Help

If persistent condensation continues despite your efforts, it may be time to seek professional assistance. Key signs indicating the need for expert help include consistent misting between window panes, water damage around the windows, and deteriorating window seals. 

At Premier Windows, our extensive experience working with homeowners and renovation professionals ensures a comfortable and energy-efficient home. If you would like a free quote on window repair, home renovation, or to seek professional advice, complete the form below or contact us today.

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