Fire Strategy for Mixed-Use Buildings

What makes mixed-use fire strategy more complex than single-use buildings

Mixed-use buildings present a fire safety engineering challenge that single-use buildings do not: the occupancy, evacuation strategy, and fire safety systems required for residential use are fundamentally different from those required for commercial, retail, or leisure uses. A residential flat above a restaurant operates a stay-put policy. The restaurant below requires simultaneous evacuation. The fire strategy must address both, and critically must address the interface between them — the structural compartmentation that separates the residential floors from the commercial floors, and the means by which a fire in one part of the building does not compromise the occupants of another.

Mixed-use fire strategies are commonly required at planning stage, where the development involves residential above commercial uses. In London, the Mayor's London Plan Policy D12a requires a fire safety statement for major planning applications, and for mixed-use schemes this must address the separation strategy between residential and non-residential uses, the means of escape for each use, and the firefighting access arrangements. For taller mixed-use buildings above 18 metres with residential accommodation, the building is classified as higher-risk under the Building Safety Act 2022 and the fire strategy must be submitted to the Building Safety Regulator at Gateway 2 (pre-commencement). Building control requires a fire strategy for any mixed-use conversion or new-build where the change of use or complexity of the building warrants it.

Mixed-use buildings are governed by Approved Document B, which provides guidance on separation between different occupancy types. Where the building contains residential use, BS 9991:2015 applies to the residential element. Where it contains commercial premises, the Regulatory Reform (Fire Safety) Order 2005 applies to the non-domestic portions and the common areas that serve them. For higher-risk mixed-use buildings above 18 metres, the Building Safety Act 2022 and associated regulations apply. The fire strategy must navigate all applicable standards simultaneously and demonstrate that each occupancy is adequately protected without compromising the others.