Guide
Safe occupancy and your fire risk assessment: where the number lives
Updated
If you only ever produce one capacity figure, make it this one. It is legally required work, it is evidenced, and every other regime will accept it as a starting point.
The underlying duty
Under the Regulatory Reform (Fire Safety) Order 2005 the responsible person for non-domestic premises must carry out a fire risk assessment and review it regularly, tell staff about the risks identified, put in place and maintain appropriate fire safety measures, plan for an emergency, and provide information, instruction and training (gov.uk, legislation.gov.uk). The responsible person can be the employer, owner, landlord, occupier or anyone else with control of the premises, and where there is more than one they must work together.
How occupancy gets fixed
- Escape route capacity is the real constraint. Approved Document B ties the number of escape routes to occupant numbers: up to 60 people needs one, up to 600 needs two, more than 600 needs three.
- Exit widths matter as much as counts. A room that passes on floor area can still fail on the width and number of its final exits, which is why an assessor may give you a lower figure than the arithmetic suggests.
- Measure the right area. Include counters and display units; exclude stair enclosures, lifts, sanitary accommodation and other fixed structure.
- Mixed use takes the harsher factor. Where part of a building is used for more than one type of accommodation, the most onerous factor applies to that part.
There is no statutory review interval
This is where a lot of published advice invents a rule. The Fire Safety Order requires the assessment to be reviewed regularly and kept up to date, particularly where it is no longer valid or there has been a significant change. It does not set a legal interval such as twelve months. Annual review is common practice and sensible, but do not let anyone sell it to you as a statutory deadline. What genuinely triggers a review is change: layout, use, occupancy, fire safety measures or a near miss.
Why this figure earns its keep
The Home Office lists safe occupancy for fire safety as the first accepted method of establishing expected numbers under the Terrorism (Protection of Premises) Act 2025, and licensing authorities routinely take it as the basis of any capacity condition. One properly evidenced number can serve all three regimes. Two conflicting numbers, from a fire strategy and a licence, will be noticed by whichever regulator arrives first.
Guidance documents for particular premises types are collected on gov.uk under fire safety law and guidance for business: gov.uk.