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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Adding a storey on top of an extension will always require an application for planning permission.

If you want to add a storey on top of your house under permitted development rights, it must be on the principal part of the house.

If you want to add an additional storey on top of your house, it can be permitted development. It is only permitted development if it follows certain rules:

The current house

• Is not a building containing one or more flats, or a flat contained within such a building
• Was constructed between 1 July 1948 and 28 October 2018
• Has not already had additional storeys added to it
• Is not on Article 2(3) land or a site of special scientific interest
• Was not changed to be used as a house (from a previous non-residential use) under permitted development rights.

How many storeys can you add?

• If the house is one storey then one storey can be added
• If the house is two or more storeys then two storeys can be added

Where can the storeys be added?

• The additional storeys must be added to the principal part of the house. The principal part of the house is the main part of the house excluding any front, side or rear extension of a lower height (regardless of these being part of the original house or subsequent additions).
• Engineering operations must only include works within the existing curtilage of the house to strengthen existing walls and foundations

How high can it be?

• The house cannot exceed 18 metres in total height
• Each storey cannot add more than 3.5 metres to the total height
• If the house is not detached the total height cannot be more than 3.5 metres higher than the next highest building that the house is attached to, adjoins, or is in the same row as.
• The additional storeys must have an internal floor-to-ceiling height of no more than 3 metres, and no greater than the internal height of any existing storey within the principal part of the house.

What materials can be used?

The materials used must be of a similar appearance to those used in the construction of the exterior of the current house

Where can windows be placed?

Windows must not be placed in any wall or roof slope forming a side elevation of the house.

Following completion of development:

• The house must remain in use as a domestic residential property
• No visible support structures must remain on or attached to the exterior of the house
• The roof pitch of the principal part of the house must be the same as it was prior to the development.

 If any of the limits set out above are exceeded then an application for planning permission will be required. If you are unsure, you should contact your local planning authority.

Find contact details for your local planning authority.

Planning permission may be required for external insulation if it impacts the external appearance of the building. If materials are of a similar appearance to those used in the construction of the house, then permission will likely not be required.

Listed buildings will require listed building consent for any significant work.

If you live in a Conservation Area or other protected area you will need to apply for planning permission before making changes to the outside of your house.

Further information and building regulations advice is available on Planning Portal. Read our external walls common project.

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Replacing the window within a bay window is treated the same as any other window. Meaning that the replacement of windows which have a similar appearance to those previously used would not require an application for planning permission.

Repairs, maintenance and minor improvements will also not require an application.

If you live in a listed building or a designated area then different rules may apply.

For more details on replacing windows, visit our common projects section.

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If you do not seek planning permission, build without it when it applies, or do not meet specified conditions of a planning permission, this is known as a planning breach.

Your local planning authority can serve an enforcement notice on you when they consider you have broken planning rules. You may be given the opportunity to apply retrospectively, or be required to remove a building or structure, or alter it to make it acceptable.

Read about your responsibilities.