29/03/2026
Key Rules for a 6m Extension
For a single-storey rear extension to proceed without full planning permission, it must meet these criteria:
House Type & Depth:
Detached houses: You can extend up to 8 metres from the original rear wall.
Semi-detached or Terraced houses: You can extend up to 6 metres from the original rear wall.
The "Prior Approval" Requirement: For extensions between 3m–6m (semi/terraced) or 4m–8m (detached), you must apply for Prior Approval (Neighbour Consultation Scheme). The council will notify your neighbours, and if they object, the council will decide if the impact is acceptable.
Width Restrictions: A side or "wraparound" extension cannot exceed half the width of the original house. If your 6m width is more than half your house's width, you will likely need full planning permission.
Height Limits: The extension must not exceed 4 metres in height. If it is within 2 metres of your property boundary, the eaves height is restricted to 3 metres.
Land Coverage: The extension (plus any other outbuildings) cannot cover more than 50% of the land around the original house.
When Full Planning Permission is Mandatory
You will almost certainly need a full planning application if:
Your home is a flat or maisonette (PD rights do not apply).
You live in a Conservation Area, National Park, or Area of Outstanding Natural Beauty.
Your home is a Listed Building.
The extension is more than one storey (6m depth is only permitted for single storeys).
Building Regulations
Even if you don't need planning permission, you always need Building Regulations approval to ensure the structure is safe and energy-efficient.
