If you live in a conservation area and have sash windows that have seen better days, you may be considering replacing them. While it’s not impossible, there are a number of things to keep in mind when making that decision to help with design and budgeting.

Most importantly, planning permission may be the first thing to do. This month, we explore the key steps to replacing sash windows in a conservation area.

What is a conservation area?

Conservation areas are designated by local councils to preserve its particular character and/or appearance. The designation is designed to prevent changes that would be detrimental to that character, appearance, or aesthetic of the area. It also helps to reduce any drop in the value of properties within that area through any such changes.

Can I make any changes to my property?

Living in a conservation area does not mean that you can’t ever make any changes to your property, but it does mean that you are more limited in what you can do. It also means that you will have to seek permission from your local authority for certain things that you may otherwise not have to do if you were not in a restricted area.

What kind of changes can I make?

This will depend on the area that you are in and what the restrictions are as they do vary from one conservation area to another. The main thing to keep in mind is that the aesthetic and appearance of the building and area in general must not be compromised.

It used to be that timber-frame sash windows could not be replaced with anything other than timber, but that is no longer the case in most places. However, there may be lots of hurdles to overcome with the planning authority in order to do that.

When it comes to windows, the types of things that the local authority considers important in a conservation area include:

  • Window position
  • Position and arrangement of window openings
  • Sash proportions
  • Joint construction
  • Sash frame material
  • Glass thickness and profile

How do I apply for planning permission?

The first step is to talk to your local authority. Let them know what you are thinking of doing and they can give you some initial advice about what is or is not allowed. They can also advise on what you may need to consider in terms of materials and the process involved in securing planning permission. Alternatively, the government’s Planning Portal is a good place to start for information on the planning application process itself.


Again, this will depend on your local authority. It can take longer to obtain planning consent for work in a conservation area, so don’t lose hope if it takes weeks or even months for a decision. The more information you can provide, the quicker and easier the decision is likely to be, so it is well worth the time and effort to engage with your council as early as possible.

For advice and assistance when thinking about replacing your sash windows, talk to our expert team at Parsons Joinery. We have the experience and expertise to help, whether you live in a conservation area or not. Call us on 01273814870 or email us at enquiries@parsonsjoinery.com and we would be delighted to help you find the right sash windows for your home.