Fire area in Assembly uses

[Morphdesigns]

In most of the Assembly areas, in IBC section 903.2.1, one of the triggers for providing a sprinkler system is "The fire area exceeds 12,000 sqft".

I have a 2-story, main occupancy is A-3, building addition that is set into a hill. Each floor has around 9000 sqft, and each floor has grade access. The building has an total occupant load of under 3000 sqft. This is attached to another A-3 building, but these 2 buildings are separated by a 2-hour firewall, based on IBC table 706.4. The existing building is not sprinklered, due to code rules when that was built.

I have an elevator to connect the two levels. I also have an open stair to connect each level, so I cannot provide a 2-hr floor separation.

Is this 12,000 sqft fire area, the aggregate of both floor 1 and floor 2, which would give me a total of 18,000 sqft, thus requiring a sprinkler system, or is this fire area only based on 1 level, which puts me under this requirement, thus no sprinkler system?
Thanks.

 

[Paul Sweet]

IBC chapter 2 defines Fire Area as "The aggregate floor area enclosed and bounded by fire walls, fire barriers, exterior walls or horizontal assemblies of a building. Areas of the building not provided with surrounding walls shall be included in the fire area if such areas are included within the horizontal projection of the roof or floor next above."

You have to include both floors if the floor/ceiling assembly between them isn't rated.