barnconversioncost.co.uk
A Q2 2026 feasibility note

Barn conversion cost in 2026, scoped before you instruct the architect.

BCIS Online (May 2026 release): stone agricultural conversion £2,180-£2,640/m², timber £1,650-£2,180/m², portal £1,750-£2,250/m². Class Q rules current to the 21 May 2025 GPDO amendment (150 m² per dwelling, 10 dwellings / 1,000 m² site cap).
Direct answer. A UK barn conversion in 2026 typically scopes at £1,650 to £3,400 per square metre on a 150 to 250 m² envelope, before M&E and professional fees. A 200 m² stone threshing barn at mid spec, Class Q route, outside an AONB, with off-grid drainage and an ASHP, lands at roughly £510,000 to £680,000 all-in, less an indicative £18,000-£32,000 VAT431C reclaim. BCIS Online, May 2026; HMRC VAT Notice 708; SI 2025/579.
Scoping calculator

Build a budget band before you instruct the architect.

Barn type
Condition
Planning route
Spec tier
M&E and survey toggles
Scoped all-in cost band
£595,253 to £854,276
£2,849 to £3,821 per m², mid case £3,238/m²
▲
sub-£1,200£1,200-1,800£1,800-2,500£2,500+
Shell works£512,820 to £687,780
M&E and survey options£19,900 to £39,500
Professional fees£51,282 to £96,289
Contingency, 10%£53,272 to £72,728
Less VAT431C reclaim-£42,021

Indicative scoping only. Bands derived from BCIS Online (May 2026), ONS construction output (April 2026) and the published statutory fees. See /surveyor-note for the per-row sourcing.

Class Q decision tree

Five gates between today and a Class Q approval. Click any node to read the rule.

Is the building in agricultural use today?
↓
Was it agricultural on 24 July 2023?
↓
Site under 1,000 m² total floor space?
↓
Each unit under 150 m² GIA?
↓
Class Q eligibleFull planning required
Why a feasibility note

The buyer here is mid-life, has just exchanged on a redundant agricultural building, and is between £350k and £800k in mental envelope. The SERP is saturated with 4,500-word builder blogs that won't commit to a number. This site commits to numbers, brackets every one with its source, and tells you what it does not cover.

Q2 2026 anchors

BCIS, stone agricultural
£2,180 to £2,640 per m²

BCIS Online refurbishment band for stone agricultural-to-residential conversion, mid spec, May 2026 release.

BCIS Online
Class Q, per dwelling cap
150 m²

Per-dwelling cap introduced by the GPDO amendment in force 21 May 2025. Previously two-tier 100/465.

SI 2025/579
Mandatory BNG
10%

Mandatory for most full-planning applications. Class Q PD is not currently caught.

DEFRA
VAT, reduced rate
5%

Labour element on a non-residential to residential conversion. Contractor must hold evidence; some materials still 20% and reclaimed via VAT431C.

VAT Notice 708

Where to read next

Planning route

Class Q vs full planning vs listed consent. The single biggest fork in the budget.

Barn type

Three cost archetypes by substrate and structural system.

M&E and services

Where rural sites quietly add £60k-£120k to the all-in.

VAT and finance

5% labour, VAT431C materials reclaim, stage-payment self-build.

Specialist consultancies

Planning consultants and conservation architects who actually do this work.

Hidden costs and timeline

Audit-able line ledger plus an 18-24 month cashflow.

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.