A roof window (or skylight) is fitted flush within the slope of a roof, while a dormer projects outward, creating additional headroom and floor space.  

Both can be installed under permitted development but must meet specific size and position limits to qualify.  

Also consider building regulations for a new dormer, find out more on Planning Portal  

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Categorising land and buildings according to their type and purpose is known as Use Classes.  

A 'Change of use' can be within the same Use Class or from one Use Class to another.

You will need planning permission for certain changes to the use of a property such as changing from a residential use to a business use. However, it is possible to change use between some classes without having to make an application for planning permission.

Depending on the specifics of any proposed change of use, including any building work associated with the proposal, an application for planning permission or prior approval may be required.

Planning permission is not required to remove an internal chimney breast as the change does not impact the exterior of the house. Rules may differ if you are planning on removing the chimney stack, or if you are in a conservation area.

If you live in a listed building, then you will need to apply for listed building consent for any major changes to the building.

Building regulations approval will always apply when removing chimney breasts as they are part of the building’s structure. You should seek advice from a structural engineer who will provide drawings and calculations that can be submitted as part of your application.

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Bricking up or infilling an existing window is classified as permitted development, meaning an application for planning permission is not required to complete the works. You will need to ensure that any materials used are of a similar appearance to the existing exterior of the house.

If you live in a listed building, then you will require planning permission and listed building consent for the change. In this instance it is best practice to talk to your local planning authority first.

For houses, replacing windows with double glazing usually doesn’t require planning permission, provided the style and appearance are similar to the original. However, if you live in a flat/maisonette, listed building, or a conservation area, planning permission or listed building consent may be required, especially if the changes affect the external appearance.

Read more about planning permission for windows and doors for houses

Read about planning permission for windows and doors for flats and maisonettes

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