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Do I Need Planning Permission for a Rear Extension?
Rear extensions are common — but knowing whether yours needs planning permission can save time, money, and stress. This guide explains the rules and how to avoid mistakes.
Rear extensions are one of the most popular home improvements — but knowing whether you need planning permission is not always straightforward.
What usually qualifies under permitted development?
Single-storey rear extensions often fall under permitted development if they meet specific criteria:
– No more than 3 metres deep (semi or terrace) or 4 metres (detached)
– Not higher than 4 metres
– No more than half your garden is covered by buildings
However, these rights can be removed for properties in conservation areas, flats, or listed buildings. The materials must also be “similar in appearance” to the existing house.
Why it is easy to get caught out
A 3.1m extension instead of 3m could trigger the need for a full planning application. Likewise, side-return additions or roof lanterns could cause issues if not considered carefully.
Next steps
If you are unsure, do not guess — check. Planning Buddy gives you a clear, tailored report in minutes so you can move forward with peace of mind.