Group S-2 is the low-hazard storage occupancy in the International Building Code. Parking garages, open or enclosed, fall in S-2 whether they have one level or ten.
Occupancy classification is the first code question for any building, because it drives allowable height and area, fire protection and separations. Garages get their own rules in IBC Section 406, which then sorts them by how they are built and ventilated.
S-2 versus S-1
- S-2 (low hazard). Storage of noncombustible or low-hazard material, including parking garages used for parking.
- S-1 (moderate hazard). Storage with more fuel load, including motor vehicle repair garages. A garage that adds repair or service functions may change classification for that area.
What follows from S-2
- Open or enclosed. An open parking garage meets opening requirements and relies on natural ventilation; an enclosed parking garage needs mechanical ventilation and, under the IBC, sprinklers. See sprinkler design density.
- Construction type and size. Open S-2 garages get generous height and area allowances for their construction type.
- Mixed use. Where a garage sits under or beside other occupancies, rated separations apply. See Type I construction and fire resistance.
The Parkonomics view
S-2 is the easy part. The decisions that cost money come next: open or enclosed, the construction type and what sits above. Make all three together, early.
Related terms: International Building Code, Open-Air Facility, Enclosed Parking Garage, Type II Construction, Building Code, Authority Having Jurisdiction