AONB barn conversion cost
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.
AONB designations close Class Q for most barns. Conservation-led design pushes the cost premium 12% to 18% above an equivalent unrestricted site, driven by stone, slate, lime mortar, traditional joinery and longer LPA timelines.
AONB and Class Q
Class Q is not available in AONBs (now branded as National Landscapes), under the GPDO Article 3 restrictions on Article 2(3) land. Full planning is the only route. NPPF attaches great weight to conserving and enhancing landscape character in these areas.
Where the premium lands
- Welsh slate roof on a Cotswold barn: £100 to £140 per m² over a concrete tile.
- Reclaimed stone for repairs: 30% to 70% premium over new dressed stone.
- Lime mortar repointing: £60 to £110 per m² of elevation.
- Traditional joinery (oak, painted softwood): 25% premium over standard timber-aluminium composite.
Programme effect
AONB applications often involve a Conservation Officer alongside the case officer, which extends pre-app and often adds a single-issue revision round. Allow 4 to 8 weeks of additional pre-decision time over a typical full-planning application.
Sources cited on this page