What is secondary glazing?

Secondary glazing is a lightweight aluminium window fitted inside of your existing window. It provides an alternative to ripping out old windows and replacing them with modern double-glazed versions.

Secondary glazing is designed so that its bars and sightlines exactly match those of the window it is fitted to. This means that you can’t see it from outside of the property. It has opening sections that match those on the original windows, so it doesn’t get in the way when you want to open your windows.

Fitting secondary glazing to your existing windows provides many benefits, including conservation and cost.

Where to use secondary glazing?

Any period building with original windows is a prime candidate for secondary double glazing. Your building may be listed or located in a conservation area. Or you may just love your original windows and not want to replace them. Whatever the reason, there are many thousands of UK buildings where replacing original windows would be either insensitive or forbidden.

Yet many original windows have an inherent problem. If they are more than 30 years old, it’s likely that they are single-glazed. Single-glazed windows are cold, draughty and terrible at stopping heat from inside the building escaping. And with today’s rising energy costs, that makes them expensive.

Secondary glazing solves this problem by adding a second, unobtrusive window inside the original. This creates a double-glazed effect without having to alter the existing windows in any way.

Cost & convenience

window removal

Ripping out old windows – lots of mess and disruption

It is usually much cheaper to fit secondary glazing than it is to replace your original windows with modern ones. On top of that, ripping out old windows is time-consuming, messy and often disruptive. In short, adding secondary glazing is a cheaper, hassle-free option.

Secondary glazing is simpler to manufacture and easier to fit than modern double-glazing. It uses far fewer raw materials, and you don’t have to touch the existing windows to install it.

Add all that together, and secondary glazing provides a far more cost-effective solution.


Read more on the benefits of secondary glazing and what types of property it is best suited to. And be sure to check out our range of window styles.