Barn conversion cost per square metre
Build-cost bands are the site's own indicative model, inflated to a Q2 2026 footing via the ONS Construction Output Price Index (April 2026). Class Q rules current to the 21 May 2024 GPDO amendment.
Indicative bands by barn type (our own model, mid spec, Q2 2026): stone threshing £2,180-£2,640/m², timber Dutch £1,650-£2,180/m², modern portal £1,750-£2,250/m². Condition (good / fair / shell) shifts each band by 7% to 14%.
The three cost archetypes
- Stone threshing barn. Highest cost archetype. Walls retained, lime mortar repointing, new internal frame, slate or clay tile re-roof. £2,180 to £2,640 per m², mid spec (indicative).
- Timber Dutch barn. Cheapest archetype if the curved roof is retained. Insulated infill, board cladding, internal stud lining. £1,650 to £2,180/m².
- Modern portal frame. Steel skeleton retained, clear-span M&E advantage, new envelope. £1,750 to £2,250/m². Class Q applies only if the building has been agricultural since at least 24 July 2023 and was not part of a sui-generis class.
Condition multiplier
- Good (envelope sound, roof watertight): -7% vs mid-case band.
- Fair (some repair to walls and roof): mid-case.
- Shell only (re-roof, repoint, new floors, no salvageable joinery): +14%.
Listed and Grade II premium
Listed buildings attach a 15% to 30% premium driven by lime-based build-up, slate, salvaged joinery and conservation-officer revisions. See /barn-type/listed-barn-conversion-cost.
Sources cited on this page