Calculating stage capacities

[MrD10de]

I've recently taken over the management of the tech department at my venue, and I'm looking to update our tech spec to include things like room occupancy limits - specifically for our stage area so we can definitively say yes or no when, for example, a community group asks if they can put 200 kids on stage at once.

Does anyone have any insight on how to calculate such things? I've used this calculator        to get a number that sounds sane, though I'd like to understand the working behind it so I can verify it. I've found this PDF helpful, but I confess that some of it's gone over my head and I'm unsure which room occupancy factor I should be using (as the guidance offered is focused on audience rather than performance).

[J Pearce]

Consider also, fire exit capacity and backstage holding capacity. No good being able to fit 200 kids on stage if you can't get them offstage or find space for them to have a juice break.

[MrD10de]

Thanks J, that doesn't directly answer my question but obviously bears considering.

The two main points of understanding that I'm struggling with are the following:

Occupant Density Factor

• Do different art forms (dance, music, theatre etc) have different ODF's associated with them? If yes, do I need to figure out occupancy limits for each of them and take the smallest, or is a general use calculation sufficient?
• Do I calculate the stage area separately from the auditorium, or are they considered one room? Is this affected by having either a flat floor or raised stage?
• Is there any distinction between an adult and a child in terms of what counts  as  an "occupant"?

Exit Capacity

• When determining alternative exits, where should you measure the 45 degree angle from? Perhaps I'm being needlessly dumb, but surely every exit is potentially within 45 degrees of another depending on where you are in the room.

 

[Brian]

You need a copy of "Technical Standards for Places of Entertainment" jointly published by the ABTT, the District Surveyors Association and the Institute of Licencing.

[Jivemaster]

Occupancy is a big part of the premises licence. If the licence is current then stick to those figures, otherwise you could enter a whole realm of hurt by getting a licence terminated and having to make a new application to current standards. 

I used to be very familiar with a Listed venue that let their licence lapse and had to reapply for a licence including a total rewire, new emergency lighting system, and total new toilets system, plus they were closed for six months. 

It's your Licence Holder who has the paperwork of the licence and they should refer to the licence document to find these figures. NEVER tweak the licence Issuing Officer they can say NO.

[paulears]

Brian's yellow book is a really useful and practical document, well worth getting, but I get the sense you're not quite understanding the point? If you are looking for a magic figure for a stage X wide by Y deep, you won't find it. Occupancy in the linked document is for the building - the premises where people in it expect to be safe.  Practically, the numbers backstage and on stage are determined by not just safety, but by space to wait, work and perhaps even eat? When authorities compare seated venues with standing venues, they don't just look at the numbers per m2 or foot room - they look for how the space is used. Clearly on stage this is even more variable. You can put more choir members on stage than dancers. At some point it goes wrong. Can 30 dancers get off stage quick enough for 30 more to come on, or do the new 30 have to be on stage, so the 30 can leave? See the problem? There are no 'rules' that can deal with this, because one group of 200 dancers could be safe and have space, but another group of 100 could be crazily unsafe? Quite a few licences do not quote a maximum number - maybe one area, maybe a busy bar/nightc club may have a capacity dictated, others might just specify number of fire exits per X people. There could be a 1400 capacity venue that doesn't even mention cast/crew numbers, or specify where they must be. When the numbers are not specified, then it's the venue responsibility to maintain safety. You do your own risk assessment and determine if the venue is safe. We do loads of dance events - some very well organised by the hirer, others totally disorganised - so we might have one where they only sell half the capacity of the auditorium, and fill the empty seats with performers, parents and chaperones, so backstage is less hectic. Others seem to have so many kids, usually sitting on the floor in the open spaces they fill with rails and screens, that you have to sort of wade through them. The choice to use, or not use the safety curtain in this venue is the venues choice. It is not required to be used and is not part of the venue licence. With a high capacity of kids on stage, it could be safer to evacuate, if necessary, the kids into the auditorium. What would worry me would be a full capacity auditorium, and then excess people on stage and backstage. Nowhere for them to go in an emergency. Even a false alarm would be chaotic, because the people 'in charge' would be unable to effectively evacuate them - no room. I'd suggest this is when the Technical Manager would need to form an internal rule, based on the knowledge of the venue, and the people likely to be in it. Adults vs children is another component to maximise safety. 

An external directive would no doubt be based on complete, but professional instinct. In the old Chief Fire Officer days, these people had the experience and knowledge to look around, use their history and make a decision. For 15 years our capacity was reduced to 1200, from 1426. One day the venue was hired by the licensing authority, who needed 1400 seats. The 1200 was increased simply by adding one of the exits into the calculation which we had always not done - it's an access to a bar, that has big exits. It was determined to be an effective and adequate extra fire exit and the capacity went up again. 

It's really going to be on your shoulders, I suspect.

 

 

[ANDYLASER]

6 hours ago, MrD10de said:

I've recently taken over the management of the tech department at my venue, and I'm looking to update our tech spec to include things like room occupancy limits - specifically for our stage area so we can definitively say yes or no when, for example, a community group asks if they can put 200 kids on stage at once.

Does the stage have a weight limit? 200 kids is a fair weight.

[kerry davies]

Get Brian's book but even when you have all the books, pdfs and calculators you still have to use your own judgement.  Just as when making Risk Assessments things like youth, inexperience, genre, activity, group cultures and much else has to be taken into consideration. There will be occasions when the numbers, calculators, books and guidance says "yes" and common sense says no. I once built a stage for bands which, at the last minute, they wanted to put 19 dancers on.

"Where did you rehearse?"

"In the youth centre."

"Isn't that 80 feet by 30 feet? Well this stage is 16 x 20 and 2metres high not a flat floor. You are doing it on the grass." 

As Andylaser says 200 kids is a fair weight but might be OK when 50 is not because they want to hop in unison.

Edited February 18, 2023 by kerry davies
E2A

[Robin D]

I was chaperoning when we had approaching 300 on stage for a show finale with two Stagecoach Schools some years back. Backstage organisation was interesting! The Technical Manager OK'd it on the strict understanding it was not a dance or bouncy number! 

It was a very big stage though, but getting that number on to stand, in silence, behind the closed Tab's, while the final bits were going on in front was rather challenging!    

[ImagineerTom]

Also capacities in an area of a venue aren’t just defined by the physical area but also by the width and number of fire exits SPECIFCALLY available from that area (almost certainly you cannot evacuate people from the stage and out the auditorium exists since that would involve going down narrow FOH side stage stairs) but also the number of toilets available backstage for them to use, the size of the corridors and flow spaces available backstage. There’s a reason why once you have a license and a set of figures you fight to keep hold of them!