Misted Double Glazing Replacement

Don’t suffer misted windows!

Misted double glazing replacement is one of the most common problems that Cheltenham Glass and Glazing are called on to rectify, where moisture enters the window cavity and causes condensation. This usually happens in older units however it can also happen in newly fitted uPVC windows.

We will try to repair a misted unit if this is what our customers prefer. One process that we use involves drilling in to the glass pane and injecting a special drying agent to help dry out the condensation that is trapped between the window panes. In addition, we can add an anti-fogging agent to help avoid the problem reoccurring. Unfortunately these processes do not come with a guarantee and the problem could redevelop.

Our expert fitters can also try to replace window gasket seals if they have perished or shrunk which will help to prevent water ingress. However we would recommend that you don't try this yourself as it is a complicated and delicate job which requires the right tools and skills.

If we are unable to repair a misted window we will provide a competitive quote to replace the failed unit, rather than the entire window and frame.

To speak to one of our experts, please give us a call on 01242 238 887 or use our contact form.

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The Cause of Misting Units

uPVC windows become misted up when the seal between the panes of glass and frames fails. A properly sealed unit can tolerate the miniscule amount of moisture that will normally permeate a properly sealed unit. When a seal fails the desiccant within the spacers won’t be able to cope with the excess moisture that gets inside the frame. This causes condensation to form and the window to appear misted between the panes of glass. 

There are various reasons why seals can fail, creating a ‘blown’ unit. Some causes that Cheltenham Glass and Glazing commonly find are: 

  • A poorly sealed unit (usually a manufacturing fault).
  • Flexing of the unit, especially in larger windows such as conservatory panels or picture windows.
  • Poorly fitted exterior rubber seals.
  • Poor installation of the window, being incorrectly seated on the glazing blocks.
  • Incorrect packers used in installation (solid, flat packers tend to block the small drainage holes in a frame. Bridge packers should be used to allow all important air circulation.
  • Deterioration of the unit with age.
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"I have had Cheltenham Glass & Glazing carry out work on my house on a number of occasions now and have been pleased every time. I would highly recommend them."

Can the Windows be De-misted?

uPVC Windows can be demisted depending on the extent of the damage. The repair process requires drilling of the glass and the fitting of plastic valves to allow the additional water to drain away. 

The repair of misted windows is not considered to be a particularly effective or long-term solution. Cheltenham Glass and Glazing do encourage customers to consider replacing misted window units where possible as a repaired unit will be more likely to fail again, causing more headaches for the property owner.

Having the unit stripped and replaced with a new one by Cheltenham Glass and Glazing, although the more expensive option, will be the cheapest long term. Under normal circumstances, correctly sealed double-glazed units should have an effective life of at least 20 years.

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Providing fast, friendly advice and fitting, based on over 10 years experience in the glass fitting industry, our staff take pride in delivering the best possible service to all our customers. So, if you are looking for the best aluminium and UPVC windows & doors Cheltenham has to offer, contact Cheltenham Glass and Glazing today.

01242 238 887

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1 Tremblant Close, Cheltenham, GL52 5FL