Secondary-glazing windows are a great alternative to double glazing. It’s possible to DIY or use an installer for this process. It doesn’t involve completely replacing the windows but rather adding a pane of glass to existing single glazed windows, so it tends to be a much cheaper option than installing double-glazing windows and a great one for those who are unable to replace single glazing. Our guide will take you through what secondary glazing is, how much it could cost you and who it’s best for.

What are secondary glazing windows?

Secondary glazing essentially involves adding a single glazed pane of glass or plastic to the frame of an existing single glazed window. It’s an effective way to keep heat in and save on energy bills and is a cheaper and easier way to upgrade single glazed windows than to completely replace them with double glazing ones.

The panel is installed on the interior of the existing window, creating an extra layer of insulation and security. As it’s fitted onto the inside of the window, the panel won’t be visible from the outside, but it’ll make the windows harder to break and will also reduce noise.

Why should I get secondary glazing?

It’s better suited for listed buildings 

Upgrading from single to double glazing on listed or historic buildings or houses in conservation areas might not be allowed, and that’s where secondary glazing can come in – you won’t need to completely replace the windows, and it’s a temporary measure that’s easy to do yourself.

It can help with noise reduction

Historically special houses, such as this one, might be prohibited from replacing draughty single glazed windows with new double glazed units. Secondary glazing allows homeowners to increase efficiency in their older properties.

Some research suggests that secondary glazing can reduce outside noise more than double glazing, providing noise reduction of up to 54dB. It’s ideal for those who live on very busy roads and wish to have a bit more peace and quiet.

There’s an extra level of security

An extra pane of glass or plastic, usually of a different thickness to the glass already in your window, provides an extra layer of security. This will make the windows harder to break into.

It’s cheaper and simpler than double glazing

One of the biggest pros of secondary glazing is that it’s a DIY option (though you can hire an installer if you wish), and it’s much cheaper than installing double-glazing windows.

Type of glazingCostEnergy efficiencyNoise reduction
Secondary glazingAround £100-£500 per windowReduces heat loss by 60%Up to 54dB
Double glazingAround £250-£3,600 per windowReduces heat loss by up to 83%Up to 31dB

Secondary glazing window types

There are several different types of secondary glazing windows, including:

Hinged secondary glazing

Hinges can either sit on the sides or at the top and bottom of this type of window, which opens like a casement window

Vertical sliding secondary glazing

Vertical sliding secondary glazing is designed for sash windows, as it allows the new pane to move in the same way as the original sash window.

Horizontal sliding secondary glazing

In contrast to vertical sliding glazing, horizontal sliding secondary glazing is best suited to wide windows, and it’ll allow the pane to slide or move horizontally rather than vertically. 

Lift-out secondary glazing

This type of secondary glazing is less permanent than vertical or horizontal glazing and uses a pane that can easily be removed (or lifted out) from its frame.

Magnetic secondary glazing

With the magnetic option, your secondary pane of glass will be attached to the inside of your window with magnetic strips. If you choose to DIY your secondary glazing, it’ll likely be with this type of fitting, as it’s an easy, cheap and flexible option. 

How much does secondary glazing cost?

The cost of secondary glazing will depend on what type of windows you have and whether you opt to install them yourself or have an installer do it for you. The average cost of secondary glazing for one window, including the labour cost of installation, is around £300, but you could pay up to £550.

One of the benefits of secondary glazing is that it is an affordable alternative to potentially high double glazing costs

We’ve set out the average costs of secondary glazing for each type of window:

Type of windowCost per window
Hinged secondary glazing£350-£550
Vertical sliding secondary glazing£350-£500
Horizontal sliding secondary glazing£350-£500
Lift-out secondary glazing£300
Magnetic secondary glazing£100-£200

Secondary glazing windows FAQs