Class Q vs full planning

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.

Class Q is cheaper, faster and more constrained. Full planning costs roughly £14,000 more pre-build, takes 12-16 weeks longer, but unlocks new openings, dormers and material design freedom.

Side by side

Statutory fee per dwelling

£536 (Class Q) vs £610 (full)

Consultant package

£3,500-5,000 vs £8,000-22,000

Determination period

56 days vs 13 weeks

BNG (10%)

exempt vs mandatory

150 m² cap per dwelling

binding vs not binding

External design freedom

restrained vs unrestricted

Refusal risk (national, est.)

40-55% vs 8-15% on a good case

Which one for which barn

Sound stone or steel barn, unrestricted area, under 150 m² per unit: Class Q.
Listed, AONB, Green Belt or above 150 m² unit: Full planning (no choice).
Borderline structural condition: Class Q likely to fail; full planning gives officer discretion.
Multi-unit farmstead under 1,000 m² total: Class Q is the cheaper and faster route.

Sources cited on this page