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I Want to Alter My Windows

Windows do more than keep the weather out. They are eye-catching features that give your house character and tell its story. They could be original, or may have been altered or replaced in response to decay or changing fashion.

If your house is listed you should seek advice before making changes as listed building consent may be required. If your house is in a conservation area restrictions may apply so again speak to your local planning authority before carrying out changes. See What Permission Might I Need? and Who Do I Contact? for further information.

Why retain historic windows?

It’s important to understand your windows before deciding on work to them. Window glass was an expensive, hand-made product until the mid-1800s, when new processes made larger, thicker sheets possible. The thinness and imperfections of old glass make it attractive, but also fragile. Much has been broken and replaced over the centuries, and surviving panes are rare and valued.

Detailing around window frames has changed over time. This can help to date the window and the house. Frames can contribute to a building’s overall appearance either as part of the original design or as deliberate later changes. Historic windows were hand-made by craftsmen, often from better timber than we have today. The thinner, lighter glass meant that frames and glazing bars could be slender. Victorian and later cast glass is heavier and required thicker, stronger frames, so that sash windows were often made with ‘horns’  - where the side rails of the frame stick out a little way below the bottom rail - to make a firmer joint.

The importance of historic windows, with their wide range of styles and ages, can vary. But evidence of craftsmanship, the survival of old and rare material and detailed design are all of value, and can make them of special interest.

Repair is better than replacement

Historic windows of interest should be retained wherever possible using careful matching repair. Their complete replacement should be a last resort and is rarely necessary. If repair is beyond the skills of a good craftsperson, a like-for-like copy should be made. If your house is listed or in a conservation area with an Article 4 Direction (which restricts work you can normally do without planning permission) you are likely to require consent to make any alterations to windows whereas like-for-like repairs do not usually require any consent. If in doubt, consult your local planning authority or conservation officer.

A sash window with white-painted frame and five-piece lintel, and shut shutters inside

Can I replace non-historic windows?

Some windows do not contribute to the historic interest of your house and may even spoil its appearance. You could consider replacing them with ones that match the historic design of the property. Old photographs, or similar houses nearby, may have examples of earlier windows. We will support the removal of non-historic windows provided it is clear that they are not of interest and that the new windows are of an appropriate style. It may be possible to fit new windows with integral double glazing, subject to their detailed design.

When repairing or replacing windows it is best to consult a specialist with previous experience of historic buildings; see Finding Professional Help. For Building Regulations as they relate to windows, please see Planning Portal: Doors and Windows.

Keeping the cold out

There is no reason why older windows should not be as energy efficient as new ones. Making sure they fit well will help reduce draughts and heat loss, as will adding draught-stripping. If you have window shutters, it’s worth making sure they work and closing them at night. If your shutters are missing, consider having new ones made. 

We have researched different ways of insulating windows and found that you can significantly reduce heat loss by using window shutters, insulated blinds or thick curtains. To further reduce energy losses through windows, your house may be suitable for secondary glazing. This retains your existing historic windows and, if done carefully, will preserve the outside appearance of the house. It is important to make sure the design of the secondary glazing is compatible with any existing window shutters, panelling or mouldings.

A red brich wall with two sash windows with pale blue frames
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