Changing Windows in Your Flat

Planning Permission

If you're planning to fit new windows, such as double-glazing, in your flat or maisonette, you might need to apply for planning permission. However, you generally won't require permission for internal secondary glazing.

Typically, you won't need planning permission if you're simply swapping old windows for new ones that look exactly the same and have the same dimensions. But if your new windows look different or have a different size – for example, with a new glazing pattern – you will likely need to apply for permission.

Crucially, local councils often have very different policies and interpretations regarding window changes in flats. Therefore, you should always speak to your Local Planning Authority for guidance before you begin any work.

If you lease your flat, you might also need to get approval from your landlord, freeholder, or the property's management company before proceeding.

• Listed Buildings: If your flat forms part of a listed building, it's almost certain you'll need 'listed building consent'. Before you start, contact your local planning authority to discuss suitable designs and materials. Remember, altering a listed building's unique historic character without this consent is a criminal offence.

• Conservation Areas: If your flat is located within a conservation area and your plans include any demolition work, you might have to apply for specific planning permission for 'relevant demolition in a conservation area'. Always consult your local planning authority for guidance.

Building Regulations

Since 1 April 2002, all replacement glazing projects must comply with Building Regulations. These rules cover important aspects like how well windows insulate (thermal performance), their safety features, how much fresh air enters (air supply), options for leaving in emergencies (means of escape), and overall ventilation.