Under Martyn's Law, a premises is in scope where 200 or more individuals may reasonably be expected to be present at the same time. That sentence does a lot of work, and three phrases in it are where venues go wrong.
"Present", not "customers"
The test counts everyone at the premises, not only members of the public. Staff, volunteers, contractors, performers, caterers, bar staff and anyone else on site all count. For a volunteer-run venue this can add twenty or thirty people to a figure that was otherwise under the line.
"At the same time", across the whole premises
If several spaces can be in use simultaneously, add them together. A main hall at 180 and a committee room at 30 is a premises capacity of 210. The busiest moment of the week is often a changeover, when one group is leaving and the next is setting up.
"May reasonably be expected"
This is peak use, not average use. A regular annual event that brings 300 people is reasonably expected, even if 51 weeks of the year the building holds forty. A one-off that has happened once in a decade is a different matter.
Methods for estimating
The statutory guidance recognises several approaches, and you should use whichever gives the most reliable figure for your building:
- Existing fire safety figures. If your fire risk assessment states an occupancy figure for a room, that is usually the best number you have.
- Ticketing or booking data. For venues that sell tickets, historic peak attendance is strong evidence.
- Headcount. If you have counted at busy events, use it.
- Floor area. Where you have none of the above, floor space factors give a reasonable estimate.
Floor space factors
These are the occupancy factors used routinely in fire safety assessment. They are a starting point rather than a legal answer, and a stated figure from your own fire risk assessment is always better.
| Type of space | Floor area per person |
|---|---|
| Standing area, bar, dance floor | 0.3 m² |
| Hall with no fixed seating | 0.5 m² |
| Seated dining, café, function room | 1.0 m² |
| Meeting or committee room | 1.0 m² |
| Exhibition or display space | 1.5 m² |
| Shop or retail floor | 2.0 m² |
| Office | 6.0 m² |
Use net usable floor area. Exclude the stage, the bar servery, the kitchen, storage and corridors.
Six things venues forget
- Staff and volunteers, especially at the events where there are most of them.
- Rooms in use at the same time as each other.
- Contractors, caterers, performers and their crew.
- Outdoor areas under your control: marquees, car parks used for events, churchyards during a fair.
- The once-a-year day. The village show, the Christmas fair, the wedding that pays for the roof.
- Changeovers, when one group overlaps with the next.
Work it out
The capacity calculator takes your spaces one at a time, applies the factors above where you do not have a figure, adds your people, and tells you which tier the result puts you in.