At Cove Windows, we are often asked how long double glazing should last before misting becomes a problem. It is a common concern for homeowners in the UK, especially as windows age and seals begin to weaken. Double glazing is designed to be long lasting, but like any home improvement product, it does have a lifespan. Misting, also known as condensation between the panes, is usually a sign that the seal around the glass unit has failed. When this happens, moisture gets inside the sealed unit and creates that cloudy or foggy appearance that many people notice. Understanding how long double glazing should last, what causes misting and how to prevent it can help you get the best out of your windows for as long as possible.
What Is Misting in Double Glazing?
Misting happens when moisture gets trapped between the two panes of glass in a double glazed window. This area, known as the sealed unit, should be airtight and filled with either air or gas, usually argon, which improves insulation. When the seal around the glass fails, warm air containing moisture from inside the home can seep into this gap. Because the space is cooler than the inside of the house, condensation forms, creating a cloudy or misty appearance that cannot be wiped away.
This type of condensation is different from moisture on the inside or outside of the glass, which can happen naturally when temperatures change. Misting inside the panes is a sign of a failure in the window unit itself. Once misting starts, the insulating properties of the window are reduced, meaning your home may lose more heat and feel less comfortable.
How Long Should Double Glazing Last?
Good quality double glazing can last anywhere between 15 and 35 years, depending on the materials used, how well it has been installed and how it has been maintained. At Cove Windows, we only supply windows from trusted manufacturers to ensure they meet high standards of durability and performance. However, cheaper or poorly fitted windows may not last as long and could begin to show signs of misting much earlier, sometimes in as little as five to ten years.
The lifespan of double glazing is affected by several factors. uPVC frames tend to last longer than timber because they require less maintenance and are less prone to warping or rotting. Aluminium frames are also extremely durable and can last for decades with minimal upkeep. The location of your home can also make a difference. Properties exposed to harsh weather, strong winds or high levels of moisture may find that seals deteriorate faster.
If your windows are well looked after, cleaned regularly and kept in good condition, they are far more likely to last for many years before misting becomes an issue.
What Causes Double Glazing to Mist?
The most common cause of misting is seal failure. Over time, the seal around the glass unit can break down due to age, exposure to extreme temperatures, and general wear and tear. As the seal weakens, it loses its ability to keep moisture out. Once water vapour gets into the gap between the panes, condensation starts to build up.
Another reason for misting can be poor installation. If the window was not fitted correctly, stress can be placed on the sealed unit, causing it to fail sooner than expected. Substandard materials also play a role. Low quality windows may not be manufactured to the same standards as reputable products, meaning they are more likely to develop issues over time.
Environmental conditions can speed up the process too. Homes in coastal areas, for example, are exposed to salty air, which can corrode seals and frames more quickly. Likewise, properties in very sunny spots may find that constant expansion and contraction of materials due to heat causes seals to weaken.
Can Misting Be Prevented?
While it is impossible to stop seals from ageing completely, there are steps you can take to prolong the life of your double glazing. Choosing high quality windows from a trusted company like Cove Windows is the first step. We ensure our products meet strict standards for durability, so they can withstand the British weather and provide long lasting performance.
Proper installation is just as important as the quality of the windows themselves. A poorly installed window will always be more likely to fail, even if it is a good product. That is why we take great care to fit every window properly, ensuring the frames and glass units are seated correctly without unnecessary strain.
Regular maintenance can also help. Cleaning the frames and keeping drainage channels free from debris prevents water from pooling around the seals. Checking for signs of damage early, such as cracks in the frame or worn gaskets, allows issues to be addressed before they lead to seal failure.
While you cannot prevent ageing entirely, good care and professional installation can mean your double glazing lasts for decades before misting becomes a problem.
What Can Be Done If Double Glazing Mists Up?
Once misting appears inside your double glazing, it is usually a sign that the sealed unit has failed completely. Unfortunately, it is not possible to simply wipe away the condensation, as it is trapped between the panes. The most effective solution is to replace the glass unit itself.
At Cove Windows, we can assess the condition of your windows and advise whether you need a full replacement or just a new sealed unit. Often, the frames are still in good condition, which means you can simply replace the glass rather than the entire window. This can be a more cost effective option, especially if the frames are relatively new and in good shape.
In some cases, particularly with older windows, replacing the entire window may be the better option. This gives you the chance to upgrade to more energy efficient products that meet modern standards, improving insulation and security at the same time.
Attempting DIY fixes or quick solutions rarely works in the long term. Specialist companies sometimes offer defogging services, but these do not solve the issue of failed seals, meaning the misting usually returns. Replacing the unit is the only way to properly fix the problem.
Why It Pays to Invest in Quality Double Glazing
Buying the cheapest windows available may seem appealing at first, but poor quality products can cost more in the long run. Low grade materials and poor installation increase the risk of early failure, leading to misting, draughts and reduced energy efficiency.
When you choose Cove Windows, you can be confident that your new windows will be manufactured to the highest standards and fitted by experienced professionals. Our products are designed to last, helping you avoid problems like misting for as long as possible. We work closely with each customer to recommend the best solutions for their home, providing windows that combine style, durability and performance.
A good set of double glazed windows is an investment in your home. Not only do they improve comfort and security, but they can also increase your property’s value and reduce energy bills. By choosing high quality products and professional installation, you give your windows the best chance of lasting decades before misting becomes an issue.
Final Thoughts
Double glazing should provide many years of trouble free performance, but all windows have a natural lifespan. With proper care and good quality products, you can expect your windows to last at least 15 to 35 years before misting becomes a concern. Once misting appears, it is a sign that the sealed unit has failed and needs replacing.
At Cove Windows, we believe that prevention is better than cure. By choosing durable products, expert installation and carrying out basic maintenance, you can significantly extend the life of your windows. If your double glazing has already started to mist, we can help by replacing the glass unit or installing new, more efficient windows that meet today’s standards.
For homeowners in Aldershot and the surrounding areas, Cove Windows is here to provide expert advice, quality products and a professional installation service you can trust. If you are worried about misting or are considering upgrading your windows, we are always happy to help and guide you through the best options for your home. Contact us today.