The free Class Q checker for UK barn conversions

Class Q is a permitted development right in the General Permitted Development Order (GPDO) that lets a qualifying agricultural building in England be converted into homes without going through full planning permission. Instead of a full planning application, you submit a 'prior approval' application, and the local planning authority has 56 days to decide whether to grant or refuse it on a defined set of grounds.

From 21 May 2024, the government significantly expanded Class Q. The cap went from 5 dwellings to 10. The total floor area allowed went from 465 m² to 1,000 m². Individual dwelling size went from 100 m² to 150 m². The old 'larger / smaller dwelling' split was scrapped. The qualifying use date was reset to 24 July 2023. A modest rear extension on existing hard surface (up to 4m) is now permitted. New prior approval considerations were added: agricultural tenancy implications and noise from adjacent farming on the new residents.

Under the post-May 2024 rules, up to 10 dwellings per agricultural unit, with a combined cap of 1,000 m² and a per-dwelling cap of 150 m². The 10/1,000/150 caps apply together — exceed any one and the scheme falls outside Class Q. The calculator above shows you which cap (if any) is the binding constraint on your scheme.

No. Class Q is excluded from National Landscapes (the new name for AONBs since November 2023), National Parks, the Broads, Conservation Areas, World Heritage Sites and Sites of Special Scientific Interest. If your barn is in any of these, full planning permission is the only route — typically pursued under paragraph 84 of the NPPF (rural design) or local plan rural exception policies.

Listed buildings are excluded from Class Q. You need listed building consent and full planning permission. The good news is that converting a listed agricultural building (a traditional stone barn, an oast house) can attract enthusiastic local plan support and Historic England guidance is generally pro-sympathetic-reuse.

The Hibbitt v Secretary of State case (2016) established that Class Q is conversion, not rebuilding. If your barn needs substantial reconstruction — new foundations, new structural frame, full re-cladding because what's there will collapse — the LPA can refuse on the grounds that the works exceed conversion. Steel-portal-frame barns can usually be converted; very dilapidated brick or timber buildings often cannot. Get a structural appraisal before committing to drawings.

Article 4 Directions are tools LPAs use to remove permitted development rights in specific areas — typically conservation-sensitive parishes or whole rural districts. Several authorities (including parts of Cornwall, the Lake District fringes and parts of the South Downs) have used Article 4 to remove Class Q. Check your LPA's Article 4 register before relying on Class Q.

Eight things: (1) transport and highway impacts, (2) noise impacts on the residential use, (3) contamination risks, (4) flooding risks, (5) whether the location or siting is otherwise impractical or undesirable, (6) design and external appearance, (7) provision of adequate natural light, and (8) the noise impact of adjacent agricultural uses on the new residents. The last one was added in 2024 and is now the most common reason for refusal in working farming landscapes.

The LPA fee is £258 per dwelling at time of writing. On top of that you'll need an architect or planning consultant for drawings and a planning statement (£3,000–£8,000 for a small scheme), a structural engineer's report (£1,000–£2,500), and any surveys the LPA insists on (bat survey, contamination Phase 1, transport statement — often another £1,500–£5,000). Most small Class Q schemes total £6,000–£18,000 in fees and professional work before any building starts.

Barn conversion build costs typically run £1,500–£2,500 per m² in 2025, finished to a sensible mid-market specification. That's higher than a self-build new home (£1,800/m² typical) because you're working around an existing structure, often with bespoke joinery, more glazing, and more careful detailing to preserve the building's agricultural character. The calculator's cost output reflects this range.

Often yes. A barn with a Class Q prior approval in place typically sells for £100k–£300k more than the same barn without consent, because the buyer doesn't bear the planning risk. Many landowners get prior approval purely to sell with consent in place — that's a perfectly legitimate strategy and arguably the lowest-risk way to monetise Class Q.

All is not lost. Alternative routes: (a) full planning permission under paragraph 84 NPPF (high-quality design in the countryside), (b) Class R (conversion of agricultural buildings to other commercial uses — shops, offices, restaurants), (c) Class S (agricultural building to a state-funded school or nursery — narrow but exists), (d) local plan rural exception policies for affordable housing. A planning consultant can assess which fits.

No. This is a free rule-of-thumb tool to give landowners and rural property owners a quick, honest first read on whether Class Q applies and what scale of scheme is realistic. For an actual prior approval submission you'll need a qualified planning consultant or architect, a measured survey and a structural appraisal. Treat the calculator's outputs as a starting budget range — not a quote and not a legal opinion.