Permitted Development vs Full Planning Permission
One of the first questions Merseyside homeowners ask during a site visit is whether their proposed extension requires formal planning permission from Liverpool City Council, Sefton Council, Knowsley, or Wirral. In England, many single storey rear extensions can be built under statutory Permitted Development (PD) rights without submitting a full planning application, provided the design stays within strict dimensional rules.
However, Permitted Development is not a free for all. Even when full planning permission is not required, we always advise applying for a Lawful Development Certificate (LDC) from your local council so you have official paper proof when you eventually sell your home. Furthermore, every extension requires full UK Building Regulations approval regardless of its planning status.
| Extension Type | Typical Planning Route | Key Dimensional Guide | Building Control Required? |
|---|---|---|---|
| Single Storey Rear (Semi or Terraced) | Permitted Development (or Prior Approval) | Up to 3m standard projection (up to 6m under Neighbour Consultation) | Yes, full stage inspections |
| Single Storey Rear (Detached) | Permitted Development (or Prior Approval) | Up to 4m standard projection (up to 8m under Neighbour Consultation) | Yes, full stage inspections |
| Wrap Around L Shaped Extension | Full Householder Planning | Combines side and rear elevations beyond PD rules | Yes, full stage inspections |
| Two Storey Rear or Side Extension | Usually Full Householder Planning | Strict roof pitch, boundary distance, and overlooking rules | Yes, full stage inspections |
When You Always Need Full Householder Planning
Certain extension layouts and property locations fall outside Permitted Development rights automatically and require an 8 week Full Householder Planning application:
- Wrap around extensions that join a side return extension to a rear extension in an L shape
- Two storey side extensions or rear extensions close to a shared boundary
- Properties located within a designated Conservation Area (such as parts of Woolton, Allerton, Waterloo, or West Kirby)
- Flats, maisonettes, or newer estates where Permitted Development rights were removed by a planning condition
- Front extensions or large porches exceeding 3 square metres external floor area
Why Building Control Is Separate From Planning Permission
Planning permission assesses how your extension looks from the street and how it affects neighbouring light and privacy. Building Regulations (Building Control) assess how safely and thermally the structure is built.
At ATD Joinery & Construction, Stephen Flinn coordinates every stage inspection with local council Building Control or an approved inspector. That covers foundation trench depth, damp proof courses, floor and roof insulation values, RSJ structural steel beam calculations, foul and storm drainage, and electrical certification.