You may have spotted a misty patch between your double glazing. At first, it’s just a little fog — annoying, but easy to ignore. Then it spreads. You wipe the glass, but nothing clears. That’s not dirt. That’s the tell-tale sign of blown windows.
At Waterlooville Windows Ltd, we’ve helped hundreds of homeowners across Hampshire diagnose and replace blown windows quickly and affordably. If you’re dealing with cloudy glass or condensation between panes, you’re not alone — and you’re not stuck with it.
In this article, we’ll explain what blown windows are, what causes them, how they affect your home, and when it’s time to take action.
What Are Blown Windows?
Blown windows are double-glazed window units that have lost their seal. Modern double glazing consists of two panes of glass separated by a sealed space (often filled with argon gas) that provides insulation. When that seal fails — due to age, pressure changes, or damage — moisture gets in.
The result? Condensation forms between the panes, giving the window a foggy or “misted” look. No matter how much you clean the inside or outside, the cloudiness remains.
It’s more than just an eyesore. Blown windows compromise insulation, reduce energy efficiency, and over time, could lead to more serious issues like mould and damp.
How Do Blown Windows Happen?
There are a few common causes of blown windows:
1. Age and Wear
Over time, the seals around your double-glazed units naturally degrade. Most units have a lifespan of 10–20 years, depending on the quality and installation.
2. Extreme Temperature Fluctuations
Big changes in temperature — especially common in older homes or south-facing windows — cause the materials to expand and contract. Eventually, this can break the seal.
3. Faulty Installation
If the window wasn’t fitted correctly or the spacer bar wasn’t sealed properly, you might experience premature failure.
4. Physical Damage
Cracks in the glass or frame can lead to pressure imbalances and seal failure — another cause of blown windows.
Signs You’ve Got a Blown Window
Here’s how to tell if your windows have blown:
- Fog or condensation between the panes
- A milky, cloudy appearance that doesn’t wipe away
- Water pooling inside the frame
- Cold drafts near the window
- Your room feels colder despite heating
If you’re not sure, we can inspect it for you — quickly and without obligation.
Are Blown Windows a Big Problem?
In a word: yes — if left untreated.
Blown windows lose their insulating properties, which means your heating system has to work harder to keep your home warm. That drives up your energy bills and reduces overall comfort.
Worse still, if moisture continues to build up inside the sealed unit, it can encourage mould growth, rot the window frame, and lead to long-term structural issues.
While the glass may not be “broken” in the traditional sense, blown windows are damaged — and they need professional attention.
Can You Repair a Blown Window?
Sometimes, but not always.
There are companies that offer “window defogging” services, but these are often temporary fixes. The better, longer-lasting solution is to replace the affected double-glazed unit, not the entire window.
At Waterlooville Windows Ltd, we can swap out blown window units quickly and cost-effectively — no need to change the whole frame unless there’s further damage.
We match glass size, energy rating, and style — making it look and perform like new again.
Why Choose Waterlooville Windows Ltd?
We’ve been helping homeowners in Waterlooville and surrounding areas for years, offering a friendly, local service built on trust, quality, and great value.
Here’s why people choose us to replace their blown windows:
- Free no-obligation quotes
- Fast turnaround — often within a week
- Energy-efficient glass options
- Expert fitting with minimal disruption
- 10-year guarantees on replacement units
- No upselling — just honest advice
Whether it’s one window or the whole house, we’ll walk you through your options and get it sorted.
When to Act
If you’ve noticed one or two blown windows, now is the time to act. Seals don’t usually fail in isolation — so if one unit has blown, others may follow soon.
Replacing a misted unit early means:
- Lower energy bills
- Better insulation
- Improved appearance of your home
- Increased property value
- Reduced risk of internal damage
And trust us — waiting until winter hits makes everything harder (and colder).
Get a Quote for Blown Window Replacement
Not sure if your windows have blown? No problem — our experienced team can assess your glazing, identify any failed units, and provide a free, no-pressure quote for replacement.
We’ll always be honest about whether repair or replacement is the best option — and we’ll never suggest work you don’t need.
Final Thoughts
Blown windows may start as a cosmetic issue, but they can quickly affect comfort, efficiency, and long-term property health. At Waterlooville Windows Ltd, we offer quick, affordable blown unit replacements that restore your home’s performance and appearance.
Don’t put up with misty glass or rising heating bills — let’s get it sorted.
❄️ Think your windows have blown?
Contact us today for a free inspection and no-obligation quote.
