Mind the gap! Why replacing a misted window pane saves £££s

‘Blown’ or failed double-glazed windows in your Suffolk or Essex home don’t just look unsightly – they’ll be costing you money too.

Double glazing has many advantages from soundproofing to security, but it is often most valued as a form of insulation for your home. But to keep bills down, it’s important to ensure that your double glazing is always in good working order, so that you home is remains as energy efficient as possible. 

Of course double glazing is designed to weather well and last. Many units come with manufacturers warranties of 10 years or more. As sealed double glazed units age however, they may require repair or eventually need replacing.

Misting between the double panes is unfortunately a tell-tale sign that something is not working properly. This is often referred to as the window being ‘blown’ or as a failed double glazing unit.      

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How does moisture get trapped in my double glazed window? 

With double glazing, the secret’s in the gap. Two panes of glass are separated by a spacer bar and sealed effectively to form a single, airtight unit. The cavity in between is filled under vacuum conditions with either dehydrated air or an inert gas and primary and secondary seals prevent any leaks or ingress. This improves insulation and prevents condensation within the unit.

A transparent coating on one surface of the glass reflects heat back into the building, reducing heat loss through the window.

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Are ‘blown’ double glazed windows common?

When consumer watchdog ‘Which?’ surveyed nearly 3,500 people who had bought double glazing within the last 10 years in August 2020, only 15% reported experiencing any problems since installation.

Out of the problems recorded by the survey, failing ‘blown’ windows – where there is misting between the panes - were responsible for 12% of these issues.

Whether your double glazed windows are relatively new or have gone beyond their guarantee period, if the window seals are broken or not tight enough as a result of poor installation, damage or age, the magic formula which makes double glazed units so effective can start to fail.

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Why do double glazing seals fail and cause ‘blown’ double glazing?

The seals or gaskets on double glazed units can fail for a number of reasons. These include:

  • The weather, elements or climate - These can cause wooden frames to rot, warp or expand and the material of the seal to shrink or perish over time.
  • Build-up of condensation on the window – If mould forms overtime, it can damage the seals
  • Cleaning windows using a pressure-washer – This can weaken the seals.
  • Poor manufacture or error in the manufacturing process – Issues with the formula or curing of the sealant materials.
  • Damage during installation, or poor installation practices – Seals may have been accidentally punctured during delivery or installation.


Can damaged or failing double glazing seals be repaired?

It depends on whether the seals are separate or built in – but the good news is that misted double glazing repair experts Mr Misty Ipswich can often help you to avoid costly replacement of entire framed units.

Replacing separate seals or gaskets can reintroduce a weather seal for your window, preventing draughts, water ingress and ‘cold spots’ as well as longer term issues like mildew, rot and damp.

Fitting replacement gasket so that it is effective requires the right thickness and profile of gasket seal (wedge, bubble, flipper, fir tree, push in gasket etc) and is best undertaken by a skilled windows technician. However just replacing the seals will not restore the window to its original condition, if the gas between the panes which stops heat from passing through, has been lost.

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Can condensation inside blown double glazed units be reversed?

Unfortunately not – but misted double glazing repair experts Mr Misty Ipswich can often replace just the sealed glass at a fraction of the cost of replacing the whole double glazed window frame to resolve the issue.

If you have the option to replace a double glazed pane, it’s a good time to consider installing the latest high performance insulating glass to save even more energy and money.  

You may also wish to include ‘warm-edge’ spacerbars in your new double glazed panes. These are made of extremely efficient insulating material and serve to overcome thermal bridge issues in the corners or your windows, making your glazing even more energy efficient.

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What will replacing a misted window panel cost?

The cost of the work is likely to depend upon the type and size of window and on average, could cost from £80 upwards. It’s also worth checking whether other window panels in your Ipswich property are showing signs of misting as, although the total cost of replacing multiple panels may be higher than replacing just one, you may access a per unit discount for multiple replacements.

If the double glazing in your Ipswich property is relatively new and you suspect that the manufacture is defective, don’t forget to check if it still comes under warranty as you may be able to make a claim.

Blown double glazing window repairs expert, Mr Misty Ipswich, specialises in helping you to see more clearly and save you money. Don’t ignore failing double glazing issues which will lose heat from your home and drive your energy bills up. With help from Mr Misty, you can overcome your double glazing problems at a fraction of the cost of installing new framed units and make your double-glazed windows and doors even better with high performance glass options.