Everything You Need to Know About Double Glazing for Listed Buildings

Windows add a particular charm to buildings, impacting the appearance and giving information about the buildings origins and historical development. Windows in listed buildings are of real importance and should be protected as a vital part of a buildings history and character.

However, there is an increasing awareness of the need to improve the thermal efficiency of buildings and help to reduce climate change. One of the ways we can achieve this is by upgrading windows so that they are double-glazed, improving the energy-efficiency of a building. However, although well-meaning the replacement of historic windows with modern versions can often have a damaging effect on the character and appearance of the building, as well as losing pieces of fabric and architectural evidence in the process of instalment.

Here at Sash Windows we are passionate about seeing sash windows in listed buildings renovated with special care so that the building itself does not become damaged or changed in any way. However, how do you know if your building can have its windows replaced? Can you even install double glazing in listed buildings? Read on to find out more as we explain everything you need to know about double-glazed sash windows for listed buildings.

Conservation Areas

What is a conservation area? When a building or area is of historic interest, it is considered a place of national importance and is added to the National Heritage List for England.

There are three categories of listed buildings:

Grade I for buildings of the highest significance.

Grade II (5.5% of listed buildings)

Grade II (92% of listed buildings)

This listing implies extra restrictions on changes you might want to make to the building’s interior and exterior. Since the rules are different depending on the conservation area you live in, it is always important to contact the Local Authority before starting any work.

What are Listed Buildings?

Listed Buildings hold a lot of history and are one of the most significant ways in which the history of the United Kingdom is preserved and protected for future generations. It is important to know your windows before deciding do work on them. For instance, they might still be glazed with historic glass that is now very rare. The importance of historic windows, with their wide range of styles and ages, can vary. But the survival of their rare materials and detailed historical design can make them of special interest to historians and tourists alike.

Remember to check with your local planning office, if:

  • You live in a conservation area
  • You live in a listed building

Improving energy efficiency in listed buildings is an important priority in the conservation of any permeable materials, historical evidence and other documents that may be damaged by the excessive moisture in the air. Historic windows can also be damaging to either the building or the occupants’ health due to the excessive moisture, mould, mildew and timber rotting due to inefficient windows. Unfortunately, the rules surrounding listed building do not always make window replacement or renovation possible.

Am I Allowed to Replace my Windows?

Often there is a misunderstanding that because a building is listed it is protected from change. Just because your property is listed does not mean that you cannot make changes. However, we would advise that you apply for listed building consent, which allows the Local Authority to weigh the necessity of requested changes against the historical significance of the property. You must contact the Local Authority before making any changes. It may be that you are not allowed to make any changes to your windows as it could damage the historical significance or structure of the building.

You should be aware that it is highly unlikely for the local planning authorities to provide consent for the replacement of windows that can instead be repaired.


We hope you have found this article useful and that it has answered any questions you may have had about installing double-glazing in a listed building. If you have any questions or would like to discuss this subject further, please do not hesitate to contact us, we would be happy to answer any questions you may have.