In this guide
4. Change the windows of a flat
The planning regime for flats and maisonettes differs in many important ways to that which covers houses.
You should not need planning permission if you are fitting windows which are identical, like-with-like replacements. However, if the new windows differ in appearance or size to those you are replacing (for instance, different glazing patterns) you may need to apply for planning permission.
If you are a leaseholder, you may first need to get permission from your landlord, freeholder or management company
If your flat is in a listed building it is very likely you will need listed building consent and you should contact your local planning authority for advice on design and materials before you start work. Works to a listed building that affect its special historic character without consent is a criminal offence.
If your flat is in a conservation area and your proposals involve an element of demolition then you may need to apply for conservation area consent and you should contact your local planning authority for advice.