Do I need planning permission for a two storey extension?
Two storey extensions are much more limited than single storey ones. A small two storey rear extension can be permitted development in England, but side and front ones need planning permission.
Check your own two storey extension in about 20 seconds: we look up your postcode's official conservation area and Article 4 data and apply these rules to your home.
These are the rules for houses in England. Wales, Scotland and Northern Ireland have their own, similar but different. Flats and maisonettes have no householder permitted development rights.
Usually no planning permission needed if
- It is at the rear only, no more than 3m beyond the original rear wall.
- It is at least 7m from the rear boundary.
- The roof pitch matches the house as far as practical, and it is no higher than the existing roof.
- Upper floor windows in a side wall are obscure glazed and fixed shut below 1.7m from the floor.
- With everything else, it covers no more than half the land around the original house.
You need planning permission if
- It is at the side or front of the house.
- Your home is in a conservation area, national park or other protected area (two storey extensions are not permitted development there).
- Your home is a flat or maisonette: flats have no householder permitted development rights.
- Your home is listed: you need listed building consent for most work, inside or out.
- Your permitted development rights were removed by a planning condition or an Article 4 direction (ask the council, or check the planning history of your home).
Building regulations
Yes, always: structure, foundations, insulation, fire safety and escape routes from the new upstairs rooms.
Planning permission and building regulations are separate: a project can need one, both or neither.
Also think about
- A structural engineer's calculations for steels and foundations.
- Party wall notices to neighbours where the work affects a shared wall or digs near their foundations.
- A Lawful Development Certificate if you build without a planning application.
Questions people ask
Can a two storey side extension be permitted development?
No. Side extensions under permitted development must be single storey. A two storey side extension needs planning permission.
Why does the 7m rule matter?
A two storey rear extension must leave at least 7m between it and the rear boundary of your land. On short gardens this alone rules out permitted development.
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General guidance from LocalWins, last checked October 2026. It is not legal advice or a planning decision, and every home is different: confirm anything important with your council or a qualified professional.