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Aluminium Secondary Glazing Windows

Secondary Double Glazing Windows

  • Perfect for listed buildings
  • Unobtrusive design
  • Made-to-measure to reduce draughts
  • Weather resistent seals
  • Reduces outside noise
Close up of Everest white secondary glazing

What is Secondary Glazing?

Secondary Glazing is the addition of a slim second window to an existing window. It is a discreet and unobtrusive method of insulating and soundproofing windows. It is also a popular solution in areas that have restrictions on the installation of double glazed windows such as listed buildings.

Secondary Glazing Gallery

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The benefits of Secondary Glazing

A large Tudor style listed house with discreet secondary double glazing on hinged casement windows

Retain your original style

Secondary glazing for listed buildings or conservation areas is a great solution as replacing windows can be more difficult. The slim aluminium secondary frame is unobtrusive and almost invisible from the outside, blending seamlessly into your home to retain the external character of your property.

Eliminate cold draughts

To ensure a perfect fit our Secondary Glazing is made-to-measure, eliminating draughts or rattles from your old elegant windows. The thermally toughened secondary glass acts as a form of double glazing by trapping air between itself and the existing window, providing extra insulation to keep your home warmer and energy bills down. All in all secondary glazing costs you less and makes your home more cosy.

A traditionally styled window with white aluminium horizontal secondary glazing
Secondary windows with two locking points for added home security

Keep your home safe and quiet

The extremely robust frames on our secondary windows firmly close with two locking points to provide additional home security against forced entry. This extra pane of glass has also been tested to reduce noise pollution from outside which is particularly useful if you live near a busy road or an airport. Overall not only does secondary double glazing cost you less for installation it also helps you to make your home more secure and noise proof.

Guaranteed for peace of mind


Aluminium is so robust it will never rot, rust or flake making it virtually maintenance free. Secondary glazing is also our first ever product, when we started way back in 1965, which means we've been manufacturing it longer than any of our competitors.


Choosing new windows can be a daunting task, so to help you here are some popular FAQs which you might find useful.

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    Is secondary glazing the same as double glazing?
    Double glazed windows are made of two sealed panes of glass, separated by a cavity that is filled with argon gas which helps improve thermal efficiency and noise reduction. These panes are fixed into a frame which can be uPVC, Timer or Aluminum which replaces your current window. Secondary Glazing is constructed of single panes of glass, housed in a frame that is installed on the interior of the window frame, behind the current window in effect creating a second layer of glass to your existing window.
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    Does secondary glazing work?
    Secondary glazing is less expensive and easier to install than replacement windows. Secondary glazing helps with heat retention, eliminates drafts and it is also effective at reducing noise pollution.
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    Does secondary glazing reduce noise?
    Secondary glazing can reduce external noise pollution by up to 80%. The robust frames on Everest secondary glazing provides an extra pane of glass tested to reduce external noise. This can be particularly useful for properties located near busy roads or airports.
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    Does secondary glazing stop condensation?
    Condensation is caused by a temperature inversion (a balance in temperatures) where one surface is at a different temperature to another. Whilst secondary glazing will go a way to stop condensation, this can actually be controlled by ensuring your home is heated and ventilated appropriately.
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    Do I need listed building consent for secondary glazing?
    A listed building and period properties will have strict regulations when it comes to replacing windows and making structural changes. This will mean those living in such properties cannot make changes to the original windows or upgrade to double glazing. Secondary glazing offers a perfect solution, as they do not damage or alter the original windows and are fitted inside. Homeowners looking to install secondary glazing to their listed home will have to get Listed Building Consent to do so.
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    What is secondary glazing for sash windows?
    Secondary glazing for sash windows is a perfect option if you live in a conservation area or listed building. These often comprise of a vertical sliding unit fitted on the inside of a sliding sash window. The secondary glazing will sit discreetly inside the window, helping to improve energy efficiency, without impacting the façade of the property.

Our range of secondary glazing units

Secondary glazing frames

Frame colours:




Frame styles:


Vertical Sash

Vertical Sash

Horizontal Sash

Horizontal Sash

Secondary glazing handles

Handle colours:








Handle styles:
AF Handle

Modern Handle

Technical Specifications of the secondary glazing system

Everest aluminium secondary glazing
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    1. Glazing
    • Air gap created between existing window and secondary glazing panel for increased heat and sound insulation
    • BS EN 12150 - 1:2000 thermally toughened safety glass
    • Optional 6.4mm laminated glass for increased security
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    2. Weather resistant seals
    • Double seals fitted around the opening window
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    3. Locking mechanism
    • Sliding windows fitted with sprung catch locks that automatically fasten as the window is closed
    • Lockable handles and security bolts on hinged windows
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    4. Sliding inserts
    • Cleverly interlock to help prevent draughts into your home
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    5. Aluminium frame
    • Aluminium internal double glazing is low maintenance and will never rot, rust or flake
    • Slim design hardly noticeable from outside, retaining the external character of property

Everest's latest customer window reviews

5 star review for garage doors
I was very pleased with the 15 double glazed secondary windows that I requested to be installed. The process was efficient and faultless and the workmen left the property clean and tidy. I would be very pleased to recommend this company in the future. Shelia Pawson 23/6/18

Windows advice and inspiration

Read our expert advice from inspiring ideas and useful information to maintenance and tips for caring for your windows.

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