The occupant load for an R-2 building's common patio area must be calculated using an occupant load factor. The correct factor is 15 gross sq. ft. per person.

Reference to Fire Inspector Documentation:

1. 2021 International Building Code (IBC) – Table 1004.5 (Occupant Load Factor)

For outdoor areas (such as patios and terraces), the applicable factor is 15 gross sq. ft. per person.

2. 2021 International Fire Code (IFC) – Section 1004.5 (Outdoor Occupant Loads)

The 15 gross per person requirement is applied to common outdoor gathering areas in residential occupancies (R-2).

Detailed Explanation of Answer Choices:

Option A (Incorrect): 50 net per person applies to storage areas, not patios.

Option B (Incorrect): 11 gross per person is used for business occupancies (B), not residential patios.

Option C (Correct): 15 gross per person is the correct calculation factor for common outdoor spaces in R-2 buildings.

Option D (Incorrect): The code official does not assign occupant load values arbitrarily—they follow IBC Table 1004.5.

Thus, the correct and verified answer is: C. 15 gross per person.