barnconversioncost.co.uk

Home Counties barn conversion cost

Costs verified against BCIS Online (May 2026 release) and ONS Construction Output Price Index, April 2026. Class Q rules current to the 21 May 2025 GPDO amendment.

Home Counties barn conversion lands at £2,550-£3,060/m² mid spec, applying a 1.16 regional multiplier on the BCIS stone band. Green Belt is widespread, pushing most cases into full planning with the NPPF 154 re-use exception.

Why the premium

The regional cost multiplier is driven by labour-rate, not material. London-adjacent contractors charge South East premiums that BCIS captures in the regional index. End-value premium typically more than offsets the build-cost differential on a like-for-like spec basis.

Green Belt prevalence

Surrey is 70%+ Green Belt; Hertfordshire 50%+. Most barn conversion cases test the paragraph 154(c) re-use exception. The December 2024 grey-belt category eases borderline sites adjacent to settlements.

Specialists active

Savills and Carter Jonas have deep Home Counties rural-planning benches and handle the bulk of complex Green Belt casework in the region.

Sources cited on this page

Reviewed for build by O. Wakefield-Smith, Digital Signet research, Q2 2026. A chartered surveyor (RICS MRICS) sign-off is being procured for the live site. All numeric figures bracket their published BCIS, ONS or HMRC source on the page where they appear.