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Green Belt barn conversion

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.

Re-use of an existing rural building for residential is one of the limited Green Belt exceptions under paragraph 154(c). The December 2024 NPPF introduced the grey-belt category, easing release of lower-quality Green Belt land that is heavily affected by adjacent development.

The paragraph 154 re-use route

Re-use of existing buildings is one of the named exceptions to inappropriate Green Belt development at NPPF paragraph 154(c), provided the buildings are of permanent and substantial construction. Most barns of stone or steel-portal construction qualify; some timber Dutch barns are borderline.

What grey-belt changed in December 2024

The grey-belt category covers Green Belt land that makes a limited contribution to the five Green Belt purposes. For barn conversion, the practical effect is to soften LPA resistance on sites that previously sat in the "poorly-performing" category, particularly farm complexes adjacent to existing built-up areas.

Cost implications


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.