Ever noticed some strange fog between your window panes?
That’s not condensation you can wipe away. It’s a blown window – and one that’s costing you money every day in wasted energy. Plus, the longer you leave them, the more damage they can do.
Here’s what we’re going to cover:
- What blown windows actually are
- The warning signs you need to spot
- Your repair and replacement options
- Prevention that actually works
What Are Blown Windows?
Blown windows (aka failed double glazing or misted windows) are a common problem when the seal between your window panes breaks down.
Double glazed windows are designed to trap air or gas (usually argon) between two panes of glass. This creates an insulating barrier that keeps your home nice and toasty. But if that seal fails…
Moisture gets in. The insulating gas gets out. And you’re left with a window that’s not much better than single glazing.
Want to know how common this is? There are 160 million windows in UK homes and they ALL fail on average every 15 years.
The repair process depends on how badly your windows have blown. Understanding how much misted window repair costs can help homeowners budget for this important home improvement. Plus, avoid the trap of leaving blown window repair and letting the problem get worse.
The Most Common Warning Signs
Ok, so how do you know if your windows are blown? Well, there are a few tell-tale signs that any homeowner can spot.
Condensation Between the Panes
This is the big one. If you can see moisture/fog/condensation between your window panes (not on the surface) then your seal has failed.
And here’s what most people don’t realise…
You can’t wipe it away. The moisture is trapped inside the unit and it’s there to stay until you fix/replace the window.
Visible Water Droplets or Misting
Condensation sometimes does more than just fog the glass. Sometimes you can actually see water droplets forming and pooling at the bottom of the window unit.
Think how perfect those conditions are for mould to grow.
Pretty gross, right?
Energy Bills Going Up For No Reason
Watched your heating bills creep up without any explanation? Blown windows could be to blame. When the seals fail, your windows lose their insulating powers.
Recent research found 16% of homeowners had discovered defects during property surveys. Some people have spent over £5,000 to fix window problems.
Visible Seal Damage
Have a good look at your window seals. See any cracks, gaps or general deterioration? That physical damage often comes before condensation issues. So spotting it early can save you some money.
Drafts Coming From Around Windows
Feel a cold draft sneaking in around a closed window? Failed seals let more than just moisture in. They let air in too.
And why blown windows matter.
Blown Windows Matter
Homeowners who spot condensation between their panes sometimes think it’s not a big deal. Just a cosmetic problem.
But, blown windows create several serious issues.
Energy Efficiency Takes a Hit
Your heating system needs to work harder to compensate. Failed double glazing can increase your energy consumption significantly. Which means higher bills month after month.
Property Value Drops
Broken/misted windows make your house less attractive to potential buyers. It signals deferred maintenance and raises questions about what other problems you’ve been putting off.
Comfort Suffers
Cold spots near windows. Drafts that make certain rooms uncomfortable to be in. Noise from outside that you never noticed before. These things all directly impact the overall livability of your home.
Mould and Damp Risk
Moisture between the panes is a breeding ground for mould spores. Which can eventually spread to visible areas of the window.
Your Repair Options
Ok, the good news is you have options. And in most cases, blown window repair doesn’t require a full window replacement.
Replace the Glass Unit Only
This is the most common option. If your window frames are in decent condition, a glazier can simply replace the failed glass unit.
Pros:
- Costs much less than full replacement
- Takes less time to complete
- Fixes the condensation problem permanently
The process is straightforward. The old glass unit is removed and a new sealed unit is fitted. With fresh seals and new insulating gas.
Full Window Replacement
Sometimes frames are damaged or old. In those cases, full window replacement is the best choice. You’ll get modern energy-efficient glazing, updated frame materials and improved thermal performance.
More expensive upfront. But worth it if your windows are over 15 years old or the frames are damaged.
Repair Vs. Replacement Decision
The big question is – when should you replace glass units? When should you do a full window replacement?
Here’s our rule of thumb.
Do a glass unit replacement if:
- Your frames are less than 10 years old
- Frames are structurally sound
- Only a few windows are affected
Do a full replacement if:
- Windows are more than 20 years old
- Frames have visible damage
- Multiple windows have blown
Preventing Blown Windows
Prevention is always better than cure. There are some strategies that really do work to extend the life of your double glazing.
Regular Maintenance Checks
Inspect window seals at least once a year. Look for cracks, gaps or signs of deterioration. The earlier you spot a problem, the easier it is to fix before the full seal fails.
Keep Drainage Holes Clear
Most double glazed units have small drainage holes at the bottom. They let any trapped moisture escape. Keep these clear of dirt and debris.
Maintain Proper Ventilation
Good ventilation means less moisture buildup in your home. And that puts less stress on your window seals. Use extractor fans in the bathroom and kitchen.
Use Mild Cleaning Products
Some cleaning products can degrade window seals over time. Use mild soap and water for your regular cleaning.
Address Small Issues ASAP
See a small crack in a seal? Get it fixed asap. A small repair job now prevents a bigger, more expensive job later.
Cost Reality
Ok, time for some numbers. Blown window repair costs vary depending on factors like window size, type of glazing and your location in the UK.
But here’s the thing… The longer you leave repairs, the more the problem gets worse. Those extra energy bills add up month after month.
Many homeowners are surprised at how affordable glass unit replacement is. And the energy savings kick in right away after repair.
Time to Take Action
Blown windows are not something you can ignore or leave until later. They affect your comfort, your energy bills and the value of your home every single day.
The signs are there. Condensation between panes. Higher energy bills with no obvious cause. Visible seal damage. Drafts around your windows. If you spot these warning signs, the smart move is to get a professional assessment ASAP.
Whether you choose glass unit replacement or full window replacement will depend on your specific situation. But both will restore energy efficiency and get rid of that annoying condensation.
And with some basic maintenance? Your new windows should give you 15-20 years of trouble-free service.
YOU MAY ALSO LIKE: Guide to European Aluminum Windows for North American Homes
