Planning permission for two-storey extensions in Cornwall
Planning an extension in Cornwall? This is how our planning application service works, with the England rules and typical fees.
Cornwall at a glance
- Nation
- England
- Price region
- South West England
- Postcode areas
- PL, TR
- Towns covered
- 10 listed below, plus surrounding villages
- Site visits
- Free, no obligation
What a planning application involves
Getting planning permission for a two-storey extension involves checking whether permitted development applies, preparing drawings and supporting information, submitting a householder application to the council and dealing with questions until a decision is made. Many two-storey extensions need permission, especially side, wraparound and front ones.
Across Cornwall we cover Redruth (TR5), Falmouth (TR10), St Austell (PL23), Truro (TR1), Camborne (TR14) and Newquay (PL28), plus the smaller places around them.
Fees
Planning drawings are a guide of £2,000–£3,500, priced in writing before the design stage starts. Householder planning application: £548 (or £575 for applications made from 8 December 2026). Lawful development certificate: £274 (about £288 for applications from 8 December 2026).
Rules in England
In England, a householder planning application costs £548 (or £575 for applications made from 8 December 2026), and councils should decide within 8 weeks of validation. Two-storey side, wraparound and front extensions always need permission. Rear extensions may be permitted development within the 3 m and 7 m limits, confirmed with a lawful development certificate costing £274 (about £288 for applications from 8 December 2026).
Approval in England: Householder planning application: £548 (or £575 for applications made from 8 December 2026). Lawful development certificate: £274 (about £288 for applications from 8 December 2026). Councils should decide householder applications within 8 weeks of validation.
Building regulations: Building regulations approval (full plans recommended) from the council or a registered building control approver, with a completion certificate at the end.
The Party Wall etc. Act 1996 applies, so notices may be needed for work on or near a shared wall or boundary.
Getting the design right
Design to local guidance
Most councils publish guidance on extensions covering set-backs, roof heights, boundary gaps and neighbours' light. Designing to it from the start makes approval more likely and reduces the chance of being asked to make changes during the application.
A complete application
Applications that are missing drawings, the right fee or a certificate of ownership are not validated, and the decision clock does not start. We check the council's validation list so the application is complete on day one.
How we work in Cornwall
Visit and first ideas
One of our team visits your house in Cornwall, checks the walls, roof and drains, and sketches out options with you.
Drawings, then consent
We draw the scheme, check it against the rules in England, and take it through the right consent with the council.
Structure and building control
A structural engineer sizes the foundations and steels, and we get building regulations approval before work starts.
Build and hand over
We manage the build from groundworks to decoration-ready finish and hand over with the completion paperwork.
Towns we cover in Cornwall
Planning permission for two-storey extensions in Cornwall: questions
What happens if my planning application is refused?
You can change the design and apply again, or appeal. In England, a householder appeal must usually be made within 12 weeks of the decision. Often the best route is a revised design that answers the reasons for refusal. We read the officer's report and advise which option has the better chance.
Should I get pre-application advice from the council?
It can help on sensitive sites, such as conservation areas, corner plots or front extensions, where the council's view is hard to predict. Many councils charge for it and response times vary. For straightforward designs that follow local guidance, a well prepared application is often the quicker route.
Neighbouring areas
- Planning permission for two-storey extensions in Devon
- Planning permission for two-storey extensions in Swansea and Neath Port Talbot
- Planning permission for two-storey extensions in Dyfed
- Planning permission for two-storey extensions in Cardiff and the Vale of Glamorgan
All extension services in Cornwall · About planning permission for two-storey extensions
Ready to see what a second storey could do for your home?
Book a free site visit. We'll look at your house, talk through options and explain the approvals you'd need, then price the design stage in writing.