Do I need planning permission for a side extension?
A single storey side extension can be permitted development in England if it is modest. Wrap-around and two storey side extensions need planning permission.
Check your own side 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 single storey and no more than 4m high.
- It is no wider than half the width of the original house.
- It does not go past a side wall that faces a road.
- The materials look similar to the house.
You need planning permission if
- It is two storey, or wraps round the back and side together.
- Your home is in a conservation area (side 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. A side extension needs building regulations approval.
Planning permission and building regulations are separate: a project can need one, both or neither.
Also think about
- Party wall notices if it is on or close to the boundary.
- A Lawful Development Certificate for proof it is permitted development.
Questions people ask
Is a wrap around extension permitted development?
Usually not: a side and rear extension joined together is treated as one extension and normally needs planning permission.
Can I convert my side garage instead?
Converting an integral garage into a room is usually not development if the outside barely changes, but it needs building regulations. Check that no planning condition keeps the garage for parking.
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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.