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Last updated: 09 June 2021

Secondary Glazing: Increase Effeciency and Sound Proofing of Your House

What Is Secondary Glazing?

If the sound outside is driving you mad but installing double glazing in your home is not an option, you should consider secondary glazing instead.Secondary glazing is the process of adding a slim line window to your existing window units, creating a gap in between that is usually around 24-28mm wide.

Secondary glazing has many benefits. It insulates heat and reduces noise pollution significantly, which makes it a popular alternative to double glazed windows. Secondary glazing can be installed in any type of building, old or new. It’s especially, but not exclusively useful if you’re living in type I or II listed building which prohibits you from swapping out windows and doors to double glazed ones.

If you’re interested in finding out more about the installation and pricing of secondary glazing, fill-in our short 1-minute form at the top of this page to get up to 4 quotes from trusted suppliers and fitters. Our services are free and there are no further obligations involved.

Secondary Glazing

How Much Does Secondary Glazing Cost?

The secondary glazing cost depends on many different factors. However, the size of your existing units will have the biggest effect as secondary glazing panels will have to be specially fitted to them.

Unfortunately, you won’t have too much of a choice when it comes to the framing material as most companies only offer units with a slim aluminium or plastic frame.

Below we listed the average cost for secondary glazing sash windows and horizontal sliding windows. Keep in mind that, prices will defer because every home is different and that you will have to add on the VAT (Value-Added-Tax) rate. Additionally, the pricing depends on whether you decide to fit the secondary glazing yourself or hire a fitter.

Type of Window Noise Reduction Draft Reduction
Sash from £1000 from £900
Horizontal Sliding from £900 from £700

DIY Secondary Glazing Kits

Secondary glazing is much cheaper than double glazing. This is mainly because secondary glazing can be a DIY project.

A lot of companies offer DIY secondary glazing kits and there’s help available in many forums. The kits offered by companies are custom-made and contain instructions as well as a measuring guide. If you prefer to get the materials for your secondary glazing yourself, magnetic secondary glazing is the solution for you.

However, as the material can be quite pricey it wouldn’t hurt to hire a professional to fit your secondary glazing. Especially if your choice falls on more complex systems like sliding secondary glazing. After all, if you don’t feel comfortable with fitting the windows yourself, there are multiple companies that are ready to help and offer you their installation services for a low price.

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Secondary Glazing Fitter

Secondary Glazing Companies

If you decide to install secondary glazing in your home you’ll have the choice between multiple secondary glazing companies, which include manufacturers, fitters and company bodies. We summarised a few of those below.

Secondary Glazing Manufacturers & Fitters

Below we listed some of the most popular manufacturers and fitters for secondary glazing in the UK.


It was found in 1966 and is a manufacturer and fitter for secondary glazing in the UK. They use an aluminium alloy for their framing that is available in a variety of colours and shapes.

Duration Windows

Secondary Glazing by Duration Windows is one of the biggest secondary glazing suppliers in the UK. They offer a range of different styles and also provide guidance and information for fitters.

NRG Glass

The company specialises in the manufacture and fitting of secondary glazing in North London, Suffolk, Hertfordshire and Essex. You can get a free quote by contacting them by phone.

Granada Secondary Glazing

It provides you with high-quality aluminium secondary glazing. They offer DIY secondary glazing kits as well as service for arranging installations by one of their FENSA certified partners. Quotes are offered online.


The company started producing aluminium products back in 1965. Their products have a 10-year guarantee and they give you a quote after one of their staff members has inspected your home.

Company Bodies

Company bodies ensure that the installation of your double glazed units runs smoothly by protecting your rights. In the UK, the most popular government approved schemes are Certass, DGCOS and FENSA.

All three verify companies and fitters to make sure that you receive competent and high-quality service. Therefore, when looking for an installer check if they’re either Certass, Fensa or DGCOS certified.

Types of Secondary Glazing

Unfortunately, you won’t have too much of a say when it comes to the framing material. Companies generally offer you aluminium secondary glazing or in some cases plastic secondary glazing. However, you will be able to choose between different systems.
We listed the most popular ones below.

Magnetic secondary glazing

A magnetic strip can be added to the edges of your existing units and the new ones to hold the secondary glazing panels in place. Magnetic secondary glazing is easy to remove and can be a DIY project due to its simplicity.

Sliding secondary glazing

Sliding secondary glazing units are removable and hence easier to clean than fixed units. Horizontally sliding secondary glazing units are perfect for windows and doors with vertical bars while vertical sliding ones are an ideal fit for windows with horizontal bars.

Fixed secondary glazing

Fixed secondary units are one of the slimmest systems, They have pre-drilled holes which will allow you to detach them if necessary. Unlike the other secondary glazing systems, however, they can’t be easily opened, making the original window inaccessible.

Lift-out secondary glazing

Like magnetic and sliding secondary glazed units, lift-out units can, as the name suggests, be lifted out. However, they’re not recommended for areas where regular access is required.

Secondary Glazing: What Are the Advantages?

Noise Reduction

Secondary glazing can reduce noise pollution significantly. It has the potential to decrease 70-80% of noises from outside which is especially useful if you’re situated close to a highway or airport.

Heat Loss

Up to 10% of heat can be lost through uninsulated windows. Secondary glazing can reduce the amount of heat that is lost through windows as the added window acts as a barrier.

Save Money on Your Energy Bill

Because secondary glazing conserves heat inside you won’t have to use your heating system as frequently. This way you’re able to save up to £105 per year.


Secondary glazing does not require the installation of new units. Compared to double glazing it is a much cheaper option. As can be a DIY project, in some cases you will only have to pay for the material.

Fits Older Homes

Because the original window or door unit remains, secondary glazing is a perfect fit for older homes. Fits listed homes. If you live in a I or II listed building secondary glazing is for you. As you won’t be allowed to replace the windows and doors with double glazing, secondary glazing will be the next best alternative.

Secondary Glazing Advantages

Secondary Glazing: What Are the Disadvantages?

Overall Efficiency

Even though, secondary glazed windows can save you energy and money they’re not nearly as efficient as double glazing is.


Especially with older homes the original window seals might not be completely fixed. In this case, it is very easy for moisture to form in between the panes. Of course, this can be fixed by opening the window but this also allows heat to escape.


Secondary glazing needs more care and maintenance than double glazing does. Adding another window or door doubles the amount of cleaning you’ll have to do because both units have to be cleaned separately.

Secondary Glazing vs. Double Glazing

Energy Efficiency

The clear winner here is double glazing. Because the area in between the panes is much smaller and sealed properly it traps heat more efficiently than secondary glazing does.


Secondary glazing is initially the cheaper option. However, both secondary and double glazing tend to pay for themselves in the long run as you gradually make more savings on your energy bill.

Noise reduction

Secondary glazing reduces noises by up to 80 % while double glazing reduces noise pollution by up to 60%. This makes secondary glazing a clear winner in this category.


This one’s a tie. Double glazing is generally better for new homes. Their aluminium or uPVC frames can give homes a contemporary look. However, for more traditional looking and older homes secondary glazing fits best. The old windows remain as well as the property’s original aesthetics.

Find the Best Secondary Glazing Companies in the UK

Would you like to install secondary glazing in your home but don’t know where to start?
We aim to make your decisions regarding the choice and installation of your secondary glazing a lot easier.

So, if you’re interested in making your home sound-proof and heat insulating with secondary glazing, remember to fill in our form at the top of this page. It only takes a minute to fill-in and you’ll receive up to 4 quotes for free and with no further obligations.

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Ana Kukoska
Written by Ana Kukoska, Former Writer

Ana is a Content Coordinator at GreenMatch. With a background in journalism and digital marketing, she has several years of experience in research, analysis, and content creation. On top of this, her focus lies on SEO and digital PR in the following areas: geen sector, sustainability, business, innovation, and more. She and her content team have been published in reputable sites like The Odyssey Online, My News Desk, Zero Waste Home and more

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