Full planning permission for barn conversion
Full planning is the only route when the barn is listed, in an AONB, in the Green Belt, or any unit exceeds 150 m² GIA. Expect £8,000 to £29,000 in pre-build cost and a 16 to 24-week programme from pre-app to decision.
When the route is forced
- Building was not in agricultural use on 24 July 2023.
- Site is an AONB / National Landscape or designated Heritage Coast.
- Building is in the Green Belt (subject to NPPF 2024 grey-belt allowance).
- Building is listed (Grade II, II* or I).
- Any unit above 150 m² envelope, or site above 1,000 m² total.
The cost stack
Per-dwelling planning fee is £610 in England under the published fee schedule (effective 1 April 2026). A pre-app at the LPA varies from £450 to £1,800. Design-and-access statement costs £2,000 to £6,000. Ecology baseline plus protected-species walkover is £2,500 to £8,000. A BNG metric exercise lands at £2,000 to £12,000 depending on site complexity.
Timeline
Statutory determination period is 8 weeks for minor and 13 weeks for major applications, with an additional EIA screening step for sites above the relevant thresholds. In practice barn conversion full-planning programmes run 16 to 24 weeks including pre-app, with another 6 to 12 weeks to discharge conditions before works can start.