Occupancy load of multipurpose spaces

[Arch_teach]

Question: Generally, what number is used for calculating the occupancy loads for general multi-purpose spaces? like general use in a university student center, where the room is big and empty and could be used for a career fair one day, and an awards banquet the next. Would that be Unconcentrated - tables and chairs, 15 net? what can I allowably take out from gross area since it is net?

 

[Yankee Chronicler]

Since it's impossible to predict how it might be used, I would go with 1 person per 7 square feet, to allow for moveable seating (lecture hall style seating). Egress would be based on that, and the posted occupant load would be based on that. If the university subsequently decides they want to use that space for a standing-only reception event, the occupancy will still be limited to the posted occupant load.

 

[arwat23]

Depends on what the space will be used for. Could be as bad as 5 net (standing space). If I were designing a space like that, I'd probably error on the side of caution and use "standing space". The university I went to had a huge multi-purpose room in one of their buildings. I saw that used for everything from concerts (no tables or chairs) and comedy shows (chairs only) to banquets (tables and chairs) and once as test center.

If it is meant to be used as anything, then in my opinion it should have the "function" of the worst (in terms of OL) thing. Regardless, I wouldn't go above 7 net.

 

[TheCommish]

the RDP could set the design for the multiple uses the owner intends to have tin the space, the the worst governs exiting, plumbing fixture

 

[walker.t]

what can I allowably take out from gross area since it is net?

This is answered by the definition of “net floor area”:

2018 IBC Definition of “Floor Area, Net”
The actual occupied area not including unoccupied accessory areas such as corridors, stairways, ramps, toilet rooms, mechanical rooms and closets.

Since it's impossible to predict how it might be used, I would go with 1 person per 7 square feet, to allow for moveable seating (lecture hall style seating). Egress would be based on that, and the posted occupant load would be based on that. If the university subsequently decides they want to use that space for a standing-only reception event, the occupancy will still be limited to the posted occupant load.

The fact that this can be a multi-use space reminds me of a story you once shared in a different thread:

Many years ago the firm I worked for was engaged as code consultants on a university gymnasium project. They wanted to build a HUGE gym -- three full-sized basketball courts, but no bleachers. It was for practice and intramural games -- they had the "game" court in another building, which was semi-historic and in full uses. So the architects had a couple of doors and they were going to declare an occupant load of 49 people, based on three games with 10 people each, plus a few spectators and officials.

So, knowing the university, the first question we asked was if this was going to be the largest indoor space on the campus. Answer: "Oh, yes, by far the largest."

So then we asked if it rained on graduation day, might they consider holding graduation in this building? "Well, of course."

How many people attend graduation? "Around three thousand."

The architects added a LOT of doors

 

[steveray]

Under 1004.9 we have them post the OL in all configurations or uses…

 

[bill1952]

As a designer, I'd plan for egress based on the 5 SF net without a doubt. The room is too likely to be used to or a party or dance or political rally of similar event. Only in the case of some religious affiliation could I imagine it not being so, but even then.

 

[Yankee Chronicler]

"If you build it, they will come."

Many years ago I was involved as a code consultant in the design of a large addition to the main gymnasium at an urban university. The addition was to house three full-size basketball courts, with 'X' feet of space between them to avoid players on adjacent courts from crashing into one another. A college court is 94' x 50'. I think they allowed 10 feet around and between the courts, so the space was about 200' x 115' (might have been 120' but we'll go with 115). So the floor area was approximately 23,000 square feet.

The architects assumed an occupant load based on three intramural basketball games: 30 players, 6 officials, and 20 substitutes ==> 56 people. And that's what they provided egress capacity for. They had two 36" doors, at diagonally opposite corners of the space. (So they actually had capacity for about 340 occupants.)

My first question was, "Isn't this going to be BY FAR the largest indoor space on the entire campus?"

Answer: "Yes, indeed!"

Me: "So if it rains on commencement day is there any chance the university might just possibly hold the commencement ceremonies in this space?"

Answer: "Ummmm ..."

They added a metric boatload of egress doors, to accommodate moveable seating at 1 person per 7 square feet. That's 3,286 people -- which is a bit more than 56.