The replacement of windows in a house may or may not require planning permission from the Council, depending on the planning constraints on the property and the appearance of the proposed windows. If your house is a listed building or located in a conservation area, this will affect your permitted development rights, in other words, you might need planning permission or listed building consent. Please read on.
Most houses have permitted development rights, which make it possible to replace existing windows (or create new windows) without requiring planning permission from the Council, so long as the materials of the proposed windows are be 'of a similar appearance' to the materials of the existing windows, and any upper floor side windows must be obscure-glazed and non-opening. (Note that the non-opening requirement does not apply if the parts of the window that can be opened would be more than 1.7 metres above internal floor level).
It should be noted that flats do not have permitted development rights and not all houses have permitted development rights. Sometimes these rights have been removed by a condition attached to a previous planning permission or by what is known as an Article 4 Direction. If permitted development rights have been removed then planning permission will be required if there are noticeable differences between the existing and proposed windows. To find out if your property is covered by an Article 4 Direction please look here.
Please remember it's the owner's responsibility to ensure that any works are permitted development, by checking the planning history of the property, before proceeding. You can check the planning history here.
Do I need planning permission?