Fire strategy for a specific building is set by Building Control and, where the project needs one, a fire engineer. This page is general guidance, not a ruling on your building.
A new mezzanine floor counts as building work, so it needs Building Control approval, and fire usually shapes the design most. The relevant guidance is Approved Document B (fire safety), Volume 2, which covers buildings other than dwellings. It sets out the factors, size, use and how the space is occupied, that decide whether a mezzanine needs fire-resisting construction and a protected escape route, rather than one rule for every case. This guide covers those factors and what fire protection means for a steel mezzanine in practice. For the wider approvals picture, see our mezzanine building regulations guide.
Why fire is the deciding factor
Adding a mezzanine creates a new floor level, a void beneath it, and sometimes a longer route to the nearest exit. Approved Document B looks specifically at galleries and mezzanines in single-storey buildings: how big the new floor is relative to the room below it, how far anyone on it would need to travel to escape, and whether people below are at risk if it caught fire before they got out. Those questions, more than any single measurement, decide whether protection is needed.
What decides whether a mezzanine needs fire protection
- How it is used. Offices, production and retail are treated more strictly than storage, since people are on the floor longer and in greater numbers.
- Size relative to the room. A mezzanine covering a large share of the room carries more weight than a small platform in a corner.
- Number of tiers. A multi-tier mezzanine is assessed more strictly, since escape and fire spread both get harder to manage.
- People working beneath it. Staff under the deck are at risk before a fire above is even noticed, one of the strongest triggers for a fire-rated ceiling.
- Travel distance to an exit. A longer walk to a final exit makes a protected escape route more likely.
A storage-only mezzanine with a short route to an exit is commonly built without fire protection; add occupied floor space, a second tier or people underneath and the case strengthens quickly. Building Control decides case by case. If your mezzanine will hold offices rather than pallets, see our guide to warehouse, office and retail mezzanine uses.
What fire protection looks like on a steel mezzanine
Where required, protection is designed into the steelwork and deck, not bolted on afterwards:
- Column casing or intumescent coating. Columns are cased in fire-rated board or coated in intumescent paint that expands under heat. Steel does not burn, but it loses strength at high temperature, so load-bearing steel needs protecting wherever escape, or people below, depend on it.
- A fire-rated suspended ceiling under the deck. Usually the single biggest item on a mezzanine job, providing the rated separation between the space below and the mezzanine above.
- Fire-rated fascia and edge boards. Stops fire tracking into the void from the sides. Open-edge guarding (handrails) is a separate Approved Document K requirement, not part of the fire strategy.
- Fire-rated staircase enclosures. A staircase in a protected escape route needs the same fire rating as the rest of it.
- Smoke detection and emergency lighting. Usually extended to cover the new floor and the space beneath it.
| Situation | Fire protection typically required | Who decides |
|---|---|---|
| Storage-only, single tier, short travel distance to exit | Often none, or minimal (detection extension only) | Building Control, case by case |
| Occupied workspace (office, production, retail) | 60-minute structure: casings, fire-rated ceiling, fascia | Building Control, with a fire engineer’s strategy |
| Multi-tier mezzanine | Protection to each level, plus protected staircase enclosures | Fire engineer’s strategy, signed off by Building Control |
| Building already has sprinklers extending under the mezzanine | May reduce or remove structural fire protection | Building Control, confirmed on the project |
If sprinklers already extend beneath the mezzanine level, Building Control may accept that as reducing the structural fire protection needed. Confirm it before you design around it, ideally before the steelwork is ordered.
Building Control and staying compliant afterwards
Approval runs through a building notice or a full plans application (our Building Regulations guide covers the difference). Fire safety does not stop at the completion certificate: the Regulatory Reform (Fire Safety) Order 2005 puts a duty on the “responsible person”, usually the employer or building owner, to keep the fire risk assessment current. A new mezzanine means updating it for the new escape routes, any fire-rated construction added, and where smoke detection now needs to reach.
What this means for fabrication and lead time
For a fabricator, the fire strategy changes what gets built, not just the paperwork. Casings and fascia are designed into the connections and finishing sequence from the start, and a fire-rated ceiling is coordinated with the deck and services layout before installation. If the strategy changes partway through, or a use changes from storage to occupied workspace after the steel is ordered, that usually means redesigning the structure rather than adding protection to what is built, with a lead-time cost. Confirming the fire strategy before fabrication starts, alongside the loading rating in our load capacity guide, keeps the project on one build sequence.
How T C Rowan handles it
We design, fabricate and install mezzanine floors from our own workshop in Banbury, working to BS EN 1090 with in-house welders and our own erection team. Wherever fire-resisting construction is needed, we build the casings, ceiling and fascia into the steelwork design from the outset, coordinating with your fire engineer or Building Control. If the project also needs an escape route beyond the mezzanine, our external staircases and fire escapes service covers that too. See the full process in our guide to how to build a mezzanine floor, or the cost impact in our mezzanine floor cost guide. Fire strategy sits with your fire engineer and Building Control, not with us, but the steelwork that carries it out is ours from drawing to final bolt.
Further reading: Approved Document B (fire safety), GOV.UK.
If you are planning a mezzanine and need to know what fire protection your building will require, get in touch for a free quote and we will talk it through alongside the structural design.
Frequently asked questions
Do mezzanine floors need fire protection under Approved Document B?
Not automatically. Approved Document B (Volume 2, for buildings other than dwellings) sets out how a mezzanine’s fire risk is assessed rather than a single blanket rule. A mezzanine used purely for occasional storage access, with a short travel distance to an exit, is commonly built without fire-resisting construction. A mezzanine used as a workspace, one that is large relative to the room, has more than one tier, or sits above people working below it usually does need fire protection. Building Control confirms which applies to your specific building.
What fire rating does a mezzanine floor need?
Where fire protection is required, 60-minute fire-resisting construction is the figure most commonly specified for the steelwork and the underside of the deck: a fire-rated suspended ceiling beneath the floor, casing or intumescent coating on the columns, and fire-rated fascia or edge boards at the perimeter. The exact period for your building is set by the fire strategy that Building Control or your fire engineer signs off, not by a fixed number in a guide.
Does a sprinkler system remove the need for fire protection on a mezzanine?
It can reduce it, but only where Building Control agrees. If the building already has a sprinkler system that extends beneath the mezzanine level, the case for structural fire protection is often weaker, because the sprinklers are already managing the fire risk. This is a decision for Building Control on your project, not something to assume without confirming it first.
Who decides if my mezzanine floor needs fire protection?
Building Control makes the final call, usually working from a fire strategy prepared by a fire engineer for anything beyond a straightforward storage mezzanine. T C Rowan designs and fabricates the steelwork to whatever that fire strategy calls for, but we do not set the fire strategy itself or give a definitive ruling in place of Building Control.