Dance Studio Change of Occupancy: One Stair and a 60-Person Goal

The occupant load is calculated from the floor area and the use, not from the client's desired head count. For an assembly space used for dancing, the designer must confirm the applicable factor with the authority having jurisdiction; using a common unconcentrated assembly factor of 15 net sf per occupant, 3,200 sf divided by 15 equals about 213 occupants. If the space is classified as concentrated assembly or standing space, the load would be higher, not lower. The client's 64-person goal is an operational limit, not a code calculation. At 213 occupants, the space needs at least two exits, and the exits must be remote from each other. The existing layout has one exit stair; the elevator does not count as an exit for egress. The 44 in corridor and stair width may be adequate for 213 occupants under the sprinklered egress-width criteria, but width cannot cure the missing second exit. The design team should verify the exact factor and the sprinklered capacity requirements in the adopted code, then either add a second remote exit, use a horizontal exit if the adjacent building construction allows it, or reduce the calculated occupant load by reducing the usable assembly area with nonoccupiable support space. Simply posting a 60-person limit does not change the calculated load.

The existing path has three issues to test: one stair, a 40 ft dead-end segment, and a 180 ft travel distance. In a sprinklered assembly occupancy, the travel distance may be within the allowed range, but the single stair is the controlling failure. The 40 ft dead-end may be acceptable if the adopted code permits it for the occupancy and sprinkler protection, but it should be measured from the most remote point, not from the corridor entrance. Because a new exterior stair is prohibited, the practical options are: first, create a second exit through an existing interior stair or a horizontal exit into an adjacent building if the construction and ratings allow; second, negotiate a variance or alternative method with the AHJ using a performance-based analysis, which is rarely quick; third, reduce the calculated occupant load to 49 or fewer so that one exit is permitted for an assembly space, but that would require reducing the usable area to roughly 735 sf at 15 net sf per occupant, which defeats the 60-dancer program. The designer should present these options with cost and schedule implications. The 44 in corridor is not the main problem; the missing second way out is.

A change from business to assembly triggers accessibility review of the route from the public way to the studio, the elevator, the corridor, doors, and restrooms. The restrooms are on the first floor, so the designer must confirm an accessible route, signage, and whether the assembly occupancy requires accessible restrooms on the same floor or within a reasonable distance. The studio may need an accessible entrance, accessible seating or wheelchair spaces for performances, and an assistive-listening system if the performance area qualifies as an assembly space with amplified sound. The change of occupancy also triggers review of fire ratings, panic hardware at exit doors, emergency lighting, and the sufficiency of the sprinkler system for the new occupancy. The risk in lease negotiation is that the tenant signs before the second-exit and restroom issues are priced. If the landlord prohibits the exterior stair and the building cannot provide a horizontal exit, the tenant may be unable to obtain a certificate of occupancy for 60 dancers. The designer should give the client a written code summary and a contingency plan before the lease is executed, not after construction documents are complete.