If your home still has single glazing and you are realising that you would like to upgrade, you might have considered the benefits of secondary glazing as an alternative to double glazing. This might be especially the case if you live in a listed home, in a conservation area or any home where double glazing just isn’t practical. In some cases secondary glazing may be a simple financial choice. By understanding the difference between secondary and double glazing you will be able to make an informed choice for your needs.

Double glazing

A double glazing unit consists of two sheets of glass that are held together in a wooden or PVC housing. Usually a gas is pumped between the panes to boost the insulation value but sometimes it is simply a vacuum. The aim is to slow the transfer of heat from the inside of your home to the outside. This can also be achieved by adding invisible coatings to the glass.

Secondary glazing

Secondary glazing is added to your existing windows usually as an additional pane of glass or plastic across your window opening on the inside of the house. In some cases these are fixed to the window and sometimes they can be removed during the summer months. They can be designed to open and close along with your windows.


Secondary glazing is certainly the cheaper option compared to double glazing. The latter involves removing the entire window and frame and adding the new unit. This needs to be done by an expert and can be an expensive, but is a long lasting option. Secondary glazing can be installed by a DIYer and could be as easy and as cheap as a sheet of plastic and a few fixings. You can also buy DIY kits on the High Street very easily.

Energy saving

It is a well known fact that double glazing will significantly improve the heat loss from your home and will allow you to save a significant amount on your heating bills across the year. However secondary glazing, when correctly installed can have a good effect too. Double glazing is thought to be twice as effective and will save you half as much. But secondary glazing is still better than single glazing.

Noise reduction

Contrary to what you might think, secondary glazing actually reduces noise from outside your home more than double glazing. This is due to the gap between the two panes. A double glazing unit will have just a few millimetres between the panes of glass, while the gap between your single and secondary glazing could be a few centimetres or more. This reduces the noise coming in to a higher degree.

While secondary glazing may not be as attractive as double glazing it is a great option for anyone who cannot get planning permission for the latter. If correctly installed secondary can do a great job and can be a great alternative that will save you money.