Mezzanine planning permission checker

Most mezzanines are not development. Across all four UK nations, works that only affect the interior of a building are not development, so they do not need planning permission — under s.55(2)(a)(i) of the Town and Country Planning Act 1990 (England and Wales), s.26(2)(a)(i) of the Town and Country Planning (Scotland) Act 1997, and s.23(3)(a) of the Planning Act (Northern Ireland) 2011.

England and Wales have a 200 m² retail exception. Where a building is used for the retail sale of goods (other than hot food) and the mezzanine adds more than 200 m² of floor space, that is treated as development and needs permission. At 200 m² or less it does not. England cites SI 2015/595 article 3; Wales cites WSI 2015/1330 article 4. Warehouse, office and industrial mezzanines are not caught by this rule, whatever their size.

Scotland and Northern Ireland have no size threshold in force. The legislative power to bring in a retail threshold exists in both jurisdictions but has not been exercised — no development order has been made — so a mezzanine of any size is currently outside the planning definition of development. For a substantial retail mezzanine the tool still flags intensification of use, which a local planning authority can treat as a material change of use needing permission separately.

Other triggers can apply separately in any of the four nations — a change of use, a listed building, or a conservation area. And whatever the planning answer, a mezzanine almost always still needs separate consent under building regulations — Building Regulations approval in England, Wales and Northern Ireland, or a building warrant in Scotland.