Secondary Glazing: Better Energy Efficiency and Sound Proofing

Secondary Glazing can be a cost effective alternative to double glazing but there are some drawbacks.

Secondary glazing is a great alternative to double glazing when you need to reduce noise from the outside world and improve your home insulation. It doesn’t mean that secondary glazing can substitute for double glazed units.

But, if installing double glazing isn’t an option, secondary glazing can be a good choice. With secondary glazing you add a slimline window to the existing unit in your house. It creates an air gap between them, usually between 24 to 28 mm wide. This barrier stops drafts, reduces heat loss due to air convection and can reduce outside noise.

Regardless of whether your building is old or modern, secondary glazing is applicable to any type of structure. 

What’s In This Guide to Secondary Glazing?

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Secondary Glazing Costs

Like other products on the market, the cost of secondary glazing is influenced by several factors. The first of which, is the size of your existing windows and doors since these panels need to fit them perfectly.

Unfortunately, unlike some other glazing products, secondary glazing isn’t available in a great variety of materials used to manufacture the window frames. The majority of companies use slim aluminium or plastic frames.

We are in the process of collating data from British companies but until that’s done, the table below shows ball park prices for secondary glazing sash and horizontal sliding windows adjusted from sterling and including VAT.

Secondary Glazing: Do it Yourself

Secondary glazing is a lot more affordable for the simple reason that you can install it yourself.

How to Install Secondary Glazing – DIY

When preparing a DIY project for a secondary glazing installation, you have to keep in mind that DIY solutions are not as durable and efficient as professional installations. However, if you carefully plan everything and follow the instructions precisely, you can successfully install secondary glazing that will serve you well for a long time.

Here are some DIY basics for your secondary glazing installation that will give you an idea of where and how to start.

  • Before you order the materials, make sure to precisely measure the units on which you will install the secondary glazing.
  • When ordering the secondary glazing, get an extra two centimetres to take into account any movement of the unit.
  • Before installing secondary glazing, make sure to disinfect the frame.
  • Mark the layout on the frame where the secondary glazing will be installed.
  • Ensure to correctly fit the aluminium tape on the frame and the magnetic tape on secondary glazing.
  • The outer film on the secondary glazing should be removed after installation.

Secondary Glazing Kits for DIY Installation

Many companies provide secondary glazing kits that have all the necessary tools and equipment and pair this with the accompanying YouTube videos and things will begin to look a bit easier. These kits are usually custom-made and have instructions together with a guide for measurements. If you decide to choose the materials for secondary glazing yourself, magnetic secondary glazing is a great choice.


But remember that secondary glazing materials can be rather costly. If you are not confident that you can correctly install secondary glazing yourself, you can always find a professional to take care of it for a reasonable price.

Secondary Glazing Types

Even though the you are limited in the materials you can use for secondary glazing, there are a wide choice of different systems.

Magnetic Secondary Glazing


Magnetic secondary glazing is a simple system and can be a DIY project. You simply add a magnetic strip to the edges of your current windows or doors which will lock the secondary glazing panels in place.

Sliding Secondary Glazing


Sliding secondary glazing is a convenient system that can be removed and easily cleaned. Comes in two variations (horizontal and vertical sliding) and which suits your windows best depends on the window units.

Fixed Secondary Glazing


One of the slimmest systems of secondary glazing is fixed secondary units which have pre-drilled holes in them. With these, you can easily detach the secondary glazing if needed. However, unlike other systems, the original window is inaccessible and they are not easy to open.

Lift-out Secondary Glazing


As the name implies, a lift out secondary glazing can be lifted out similarly to magnetic or sliding secondary glazing. However, it may be not the best option if you need regular access to the area.

Advantages of Secondary Glazing

Secondary glazing is efficient when it comes to the reduction of noise pollution. It can filter out up to 70% of outside noise which makes it a good option for homes close to main roads or busy areas.

Up to 10% of heat can easily escape through uninsulated window units and older windows can suffer from nasty draughts. Secondary glazing adds an extra layer to the windows and serves as a barrier which reduces the amount of heat lost.

Secondary glazing preserves more heat inside your home. Therefore, you won’t need to use your heating system as often, helping you save up to £115 per year.

Secondary glazing is much more affordable than double glazing units as it doesn’t require the installation of new units. 

Disadvantages of Secondary Glazing

Secondary glazing can help you reduce your energy bills and save money, but they are far less efficient than double glazing.

Since the building seal on older windows is not as effective as with double glazed windows, condensation can form between the window and the secondary glazing panel. And unlike double glazing, secondary glazing does not provide a high level of insulation even though it helps trap the heat inside.


Compared to double glazing, secondary glazing requires higher maintenance. By installing secondary glazing, you will double the number of windows and doors that you will have to clean.

Secondary Glazing and Double Glazing Comparison

Energy Efficiency

Both secondary glazing and double glazing improve the energy efficiency of a house. However, double glazing is without a doubt the obvious winner. Since the gap between the glass panes is smaller in double glazed units and the frames are properly sealed, the heat is trapped inside far more efficiently.


The initial cost of secondary glazing is much lower. However, both types will pay for themselves in the future. Both secondary and double glazing are developed to keep heat inside the premises efficiently and with both types, you will be able to save money on your energy bills and reduce your expenses in the long run.

Reduction of the Noise

Both double glazing and secondary glazing systems are efficient when it comes to the reduction of the noise pollution. However, the secondary glazing is the winner in this case as it can reduce audible noise from outside by up to 70%-80% while double glazing is slightly less effective.

Overall Look

When it comes to aesthetics of the house, both double glazing and secondary glazing are a good fit and it really comes down to a personal choice.

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Last Updated on October 28, 2021


Author: Indra Gupta

Indra is an in-house writer with a love of Newcastle United and all things sustainable.

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