Windows are not just light providers, they can also be one of the most defining features of a property, particularly in older buildings where the windows often define the character and era of origin. Fitting the correct style of window to your property is important if you want to avoid ruining its beautiful charm. Plus, if you live in a Listed building or own a property within a conservation area, and you are not replacing your windows like for like, it is likely that you will have to get any changes you plan to make to your historic windows approved by your local planning authority and conservation officer.

If you live in a conservation area and have timber 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 should be top of your priority list. Some local planning authorities have strict rules, so it is always important to check what the rules are with your local council and submit a planning application if needed. In this article, 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 the character and/or appearance of certain areas. According to Historic England a conservation area “exists to manage and protect the special architectural and historic interest of a place.” 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.

Potential conservation areas in the UK include:

  • National parks
  • Towns and villages of architectural or historic interest
  • Areas of outstanding natural beauty
  • Historical sites.

We have supplied and installed thousands of sash windows over the many years we have been in business and are well versed with the conservation rules and regulations in and around Sussex, so we can confidently advise on your project if required.

Can I make any changes to my property if I live in a conservation area?

Living in a conservation area does not mean that you cannot 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.

Likewise, if you own a listed building (an individual building of ‘architectural or historical interest’), making changes will be more difficult to get approved. Not all buildings in conservation areas are listed – a listed building could be inside a conservation area or anywhere else. Listed buildings fall into three categories.

Article 4 Direction

The designation of a conservation area is officially referred to as ‘Article 4 Direction’. The direction is made by the local planning authority and allows local authorities to restrict or withdraw specified permitted development rights either in relation to a particular area or site, or a particular type of development anywhere in the authority’s area. In short, Historic England explain that “where an article 4 direction is in effect, a planning application may be required for development that would otherwise have been permitted development. Article 4 directions are used to control works that could threaten the character of an area of acknowledged importance such as a conservation area”.

You will hear this term a lot if your window replacement project does not fall within permitted development rights, so it is a good idea to check out more information about Article 4 Direction.

 What kind of changes can I make to the windows in my property if I am in a conservation area?

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 or casement 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 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

Repair or replace? Ideally, local authorities prefer owners to make window repairs rather than replace windows altogether. Windows should always be repaired to match the original windows as closely as possible. Like for like repairs do not require planning permission in conservation areas or in Listed Buildings, but alteration or replacement projects will require planning permission.

Can you double glaze modern timber sash windows?

Yes, modern timber sash windows are able to contain double-glazing. In fact, doing so will not only buy you great kerb appeal and value, but it will also increase your home’s energy efficiency and security too. If you are keen to preserve your existing box frames but replace your single pane sashes with new double-glazed ones; our sash window replacement service is for you.

Can you double glaze historic windows?

Yes! we can double glaze historic windows. Historically, planning officers have been famed for declining planning permission requests for replacement windows and doors with double-glazing within listed properties and homes within conservation areas, our vacuum insulated glass technology has seen this change in the last few years. In fact, you should not even need planning approval to fit it. How? It’s all thanks to the super slim (6.7mm) profile of the glass. Despite being as slim as a single glazing, it boasts thermal efficiencies greater than triple-glazing, making it ideal for retrofitting into your existing windows and ideal for listed buildings and windows in conservation areas.

The ability to get double glazed windows when you live in a conservation area or older building can be a game changer in terms of energy efficiency, security, and noise reduction.

When to replace historic windows

All good things must end eventually and the same goes for your historic windows. There will come a time when they are beyond repair and renewal and will need to be replaced fully. If this is the case, the replacements should be as similar as possible to the original windows.

Cost of replacing windows in the UK

If you want or need to replace your windows the price you pay will depend on a number of factors including the style of window and style size, window frames, type of windows, the finishes you choose and the window installer you opt for. However, to give you some idea of replacement window costs and what you can expect to pay when choosing Parsons Joinery, our average cost for replacing a sash window typically falls between £1,000 and £2,500.

Planning permission

You will need to seek planning permission for alterations to all buildings, but Listed Buildings and Conservation Areas require special permission. You will need planning permission for all work that affects the characteristics of a building, including demolition, extensions, and alterations. This particularly applies to Listed Buildings where you are required to apply for Listed Building Consent.

Some local authorities apply extra control in conservation areas, paying particular attention to doors and windows.

How do I apply for planning permission to change my windows?

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.

Timescales? 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 01273 051515 or email us at and we would be delighted to help you find the right sash windows for your home.