White sliding sash window with secondary glazing

Secondary Glazing

Secondary glazing helps lock in more heat, and reduces draughts and outside noise from getting into your home. Perfect for listed buildings and period properties, it fits behind your existing windows to provide support and insulation.

With a choice of sliding or hinged opening configurations to match your existing windows, they are easily paired with a variety of window styles. Increase privacy or add protection from the sun with a variety of obscure glass options.

Get a Price
  • Secondary glazed horizontal sliding unit in open position
  • Secondary glazing top down view in open position close up
  • Secondary glazed horizontal sliding unit on staircase
  • Secondary glazing close up top view
  • Secondary glazed horizontal sliding unit close up
  • Secondary glazing close up straight on view

Secondary Glazing is a single glazed window panel that sits behind your existing single or double-glazed window. The small gap in-between creates an extra layer of insulation by slowing the movement of heat from one side of your window to the other.

Explore Secondary Glazing Types

Close up of white secondary glazed window from the Anglian secondary glazing range

Horizontal Sliding Secondary Glazing

Designed to match your existing windows, horizontal frames slide smoothly open and closed on aluminium runners, helping keep heat in, and draughts out.

Conservation property secondary glazing in white from the Anglian secondary glazing range

Hinged Secondary

This option is ideal for traditional casement windows, as the secondary glazing swings open on a small hinge, in line with the mechanism of the window behind it.

Close up of secondary glazing on a sash window in white from the Anglian secondary glazing range

Vertical Sliding Secondary Glazing

Perfect for box sash windows, the panels in these vertical sliding frames move easily up, down and can tilt inwards to provide easy cleaning access to the original window.

Reasons to Choose Secondary Glazing

  1. Reduces Outside Noise

    The extra pane of secondary glazing adds a layer of sound insulation which helps reduce outside noise. This is particularly useful if your home has single-glazed windows or is on a main road.

  2. Easy to Maintain

    A more discreet alternative to replacing your windows, secondary glazing needs little upkeep, requiring some lubrication and the occasional clean.

  3. Tough and Secure

    Secondary glazing frames are made from uPVC and provide a strong barrier behind your existing windows. Having an extra pane of glass makes your windows harder to break than single-glazing alone.

  4. Cost–Effective Solution

    With a faster installation process and fewer materials, secondary glazing can be more affordable than replacing all your windows.

  5. Adds an Insulating Layer

    Installing secondary glazing adds another barrier that helps prevent draughts and cold air coming through your windows. This helps to lower the energy consumption of your home to reduce energy bills.

Close up of secondary glazing seal from the Anglian secondary glazing range

Working with the Best Industry Bodies to Install the Best Secondary Glazing

  • FENSA logo


    The Fenestration Self-Assessment Scheme (FENSA) ensures replacement window and door installations comply with building regulations for England and Wales. You receive a FENSA certificate to keep as proof of compliance.

  • Glass and Glazing Federation logo


    Anglian is a leading member of the Glass and Glazing Federation (GGF). The GGF is the most influential Trade Federation in the industry, recognised by government for their in-house technical expertise, which helps influence key legislation within our sector.

  • Made in Britain logo

    Made in Britain

    The ‘Made in Britain’ marque on all our products means they are made from start to finish in a British factory by British craftspeople.

  • Recovinyl Plus logo

    Recovinyl Plus

    Recovinyl is an initiative advancing the sustainable development of the European PVC industry by improving production processes, minimise emissions, develop recycling technology and boost the collection and recycling of waste.

  • TrustMark

    TrustMark is a not-for-profit organisation operating a quality mark framework in the repair, maintenance and improvement sector. Registration with Trustmark demonstrates commitment to customer service, high standards and continual improvement.

Secondary Glazing with Quality at the Heart

Secondary glazing in living room banner
Our Price Match Promise

We all want quality products at the best prices. So if you find cheaper like for like uPVC windows with another company within 7 days, we’ll match the price.

Learn more
Secondary glazing on finance

Finance makes it easy to upgrade your windows now and spread the cost. Available from just £249 deposit with 12.9% APR.

See representative example
Secondary glazing prices explained

Unlike other manufacturers, our windows are made to measure. The price you pay is unique to your project.

Learn more

Need some help?

Book a remote quote with our team on Livechat now, online Monday–Sunday 9am–5pm.

Chat Now
"Samantha was very helpful and answered all of my questions."

Our Happy Customers

Wood sliding sash window with secondary glazing
Wooden sash window customer testimony
Mr Pearson, Derbyshire

White uPVC sliding sash window with secondary glazing

“Anglian’s secondary glazing was the perfect solution for our listed building, as we couldn’t replace our windows with uPVC. We were very happy with everything and now we have a warmer home with no draughts.”
Get a Price
Wood sliding sash window with secondary glazing after

Choose Anglian for a National Company Local to you


10-year Guarantee

A 10-year parts and labour guarantee is included in your Anglian double glazing price.

Made in Britain

Made in Britain

Our products are made from start to finish in a British factory by skilled craftspeople.

Pound icon

Price Match

If you find cheaper like for like uPVC windows elsewhere, we'll match the price.

Decide if Secondary Glazing is right for your home

Your Questions Answered by us

What’s the difference between double and secondary glazing?

Secondary glazing is a pane of glass fitted in a separate frame on the inside of your existing windows. Double glazing is two panes of glass with the space in between filled with argon gas and vacuum-sealed inside your actual window frame.

How much does secondary glazing cost?

The cost of secondary glazing is determined by the size of the window opening you have and how easy it is to install. There are kits that you can buy relatively cheaply which have standard sizes. However, most period homes have odd shapes and lines around window openings, making standard sizes difficult to fit. The best secondary glazing is often bespoke because you get the perfect fit.

Do you need planning permission for secondary glazing?

You don’t usually need planning permission for secondary glazing, even on listed buildings and those in conservation areas. The main advantage of secondary glazing is that it doesn’t change the look or fabric of the building, so you retain period features outside and inside. If for any reason you do require planning permission, don’t worry, we’ll take care of everything for you.

Does secondary glazing reduce condensation?

Secondary glazing can dramatically reduce the chance of condensation forming your windows. Condensation is formed when warm moist air meets a cold surface. Secondary glazing sits behind windows that are exposed to colder temperatures, creating a barrier between them and the rest of your home. This minimises the chances of condensation forming and keeps the warm air inside.

How do you clean secondary windows?

To clean your secondary glazing all you need is warm soapy water and a cloth to wipe the frame and glass. To clean the inside of side-hinged secondary windows, open them fully and clean them as you would the outside. If your windows open on a horizontal slider, then follow the instructions to take them out of the sliders and clean the panels individually. Secondary windows on vertical sliders can be tilted open to allow for easy cleaning.

Explore Similar Products

Made in Britain
10-year guarantee
UK's Number 1
Home Improvement Provider
Want to Speak To An Advisor?
Give our team a call on 0800 014 2106

Get a Price

Up to £250 off when you get a
free no-obligation quote.

Please enter your first name
Please enter your last name

To provide you with an accurate quote, we'll call you to arrange a remote or home visit.

Enter a valid phone number

We'll email you if we can't get in touch by phone.

Enter a valid email address
Enter your house number or name

We’ll use this information to store and process your enquiry

Enter a valid postcode
By providing your details you agree to being contacted under the terms of our privacy policy.

Our Accreditations and Licenses

  • British Board of Agrement accreditation for uPVC windows from Anglian Home Improvements
    The British Board of Agrement provides certification on the quality of our products.
  • Anglian’s PVC-U Casement and Tilt & Turn windows have enhanced security performance.
  • BFRC logo
    The British Fenestration Ratings Council is the UK’s national system for rating energy efficient windows.
  • FENSA logo
    The Fenestration Self-Assessment Scheme ensures window installers comply with buildings regulations in England & Wales.
  • FSC standalone logo TIF green
    Look for our FSC® certified wooden window and door products on our website.
  • Glass and Glazing Federation logo
    Anglian is a leading member of the Glass and Glazing Federation (GGF).
  • Recovinyl Plus logo
    PVC Industry initiative to improve manufacturing, minimise emissions and develop recycling practices
  • TrustMark is a government endorsed not-for-profit organisation that operates through more than 30 scheme operators.