How to Retrofit Windows with Secondary Glazing

How to Retrofit Windows with Secondary Glazing

Given the inherent value and aesthetic appeal of natural timber windows, it’s no surprise that more homeowners are choosing to keep them rather than have them replaced. As a result, secondary glazing has become a popular solution among those who want to improve insulation without compromising on style.

So how do you use secondary glazing to retrofit windows? Read on to find out.

What exactly is secondary glazing?

Secondary glazing is an excellent way of getting the benefits of double glazing without having to replace your windows. It involves putting in an additional slim-line window on top of the ones you already have. By doing this, you will increase the performance of the following elements of your windows…

· Thermal

By adding a second piece of glass to single glazing, air will be trapped between both pieces of glass which will then increase the heat in the room. Secondary glazing is a proven and effective method of keeping your home’s temperature comfortable and consistent.

· Acoustic

Secondary glazing is an effective soundproofing method. This is because it increases your degree of privacy and comfort while protecting your house or business from outside noise. The second pane of glass, along with the gap of air, acts as an extra barrier to any sound making its way in from outside.

· Security

An effective way to strengthen security, the extra glass panel immediately reinforces your windows. The window frames lock the window from the inside and hold the glass firmly – making it much harder for anyone to break in and deterring most opportunists.

What are the benefits of retrofitting?

As well as being a quicker and easier way to keep your home warm and dry, retrofitting your windows has many other benefits. Let’s have a look at some of them.

· Preserving the original charm

You can enjoy modern performance while preserving the charm and beauty of your old windows. When it comes to historical or heritage assets, retaining the original appearance is very important.

· Cost-effective

Retrofit windows are typically less expensive than full window replacement. It allows you to reap many of the benefits of double glazing without the expense and inconvenience of completely replacing windows. This is a welcome option for homeowners who are looking to lower expenses and reduce their energy consumption.

· Reducing your carbon footprint

Secondary glazing reduces energy consumption by boosting thermal efficiency, which helps to minimise your carbon footprint. This is a great step towards more environmentally friendly and sustainable living. It’s also less wasteful as your original windows don’t need to go to landfill.

· Reduces condensation

The chance of condensation will be significantly reduced when secondary glazing is installed. Moisture isn’t likely to build up on windows as 2 panes of glass increase the warmth in the room. This is especially useful in humid locations or significant temperature changes.

· Flexible usage

Secondary glazing is offered in a variety of configurations, including fixed inserts, hinged casements, and vertical sliders. Because of this versatility, you can select the type of secondary glazing that best meets your specific demands and tastes.

How do you retrofit windows?

It’s a reasonably simple process that requires only a few basic materials. Here’s a quick guide on installing secondary glazing:

Metal/Wood/PVC frames

  • Measure both the height and width.
  • Purchase metal frames with either glass or acrylic glazing.
  • You might have to insert the panes into the frames if not pre-assembled.
  • Position them within the interior recess of the window and make sure they are aligned with the window openings.
  • Using a drill, create holes at the marked installation points.
  • Use screws to attach them to the window frame or windowsill through the pre-drilled holes.
  • Make sure the frames are level and securely fastened.
  • Apply a thin bead of sealant along the edges of the metal frames where they meet the existing window frame.
  • If the secondary glazing panels are designed to be opened and closed, install latches or catches as per the manufacturer’s instructions.
  • Test and clean.

Magnetic secondary glazing

If you’re not quite decided on secondary glazing, remember that magnetic frames are a reversible and temporary solution that can be easily removed if needed. However, you should always ensure that the magnetic strips or adhesive tape you use are strong enough to hold the glazing panels securely in place. This will avoid any potential damage to your existing windows.

While retrofitting secondary glazing can be a do-it-yourself project, it’s a good idea to consult with an expert if you are unsure about any aspect of the installation procedure. Additionally, before making any changes to your property’s windows, you should examine local building regulations.

Do-it-yourself vs professional installation

Whether you opt for DIY secondary glazing or professional installation depends on your specific project and whether you’re confident in your skills. If it is relatively simple, DIY secondary glazing installation could be suitable, especially with a fully assembled, pre-glazed and installation-ready kit.

However, for more complex windows, heritage properties or if you’re uncertain about the process, investing in professional installation can provide peace of mind and ensure the best results. Always prioritise safety, quality and your specific needs when making this decision.

Hassle-free secondary glazing installation with Clearview

Secondary glazing from Clearview is a popular choice for many clients all over the UK. Retrofitting your windows has a number of well-known benefits, including outstanding acoustic insulation, increased thermal efficiency, effective condensation control and improved window security.

As a supplier to the National Trust, Clearview has been given permission to use its products in conservation areas and Grade I and II listed buildings. Our assortment includes quality secondary glazing options that perfectly match a variety of window designs. Each item we sell is made to fit the measurements and requirements of your home.

Whether you choose a DIY installation or a professional installation, our friendly team is available to answer your questions and help you get the best results possible for your home.


Clearview secondary glazing - the solution to significantly improved acoustic and heat insulation to your property, making your home or offices more comfortable, secure, greener and cost efficient to run. Achieved without the disruption of replacement windows, and without damaging the character of your building.

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