506.2.1 Single-Occupancy, One-Story Buildings
The allowable area of a single-occupancy building with no more than one story above grade plane shall be determined in accordance with Equation 5-1:
Aa = Allowable area (square feet).
At = Tabular allowable area factor (NS, S1, S13R or S13D value, as applicable) in accordance with Table 506.2.
NS = Tabular allowable area factor in accordance with Table 506.2 for nonsprinklered building (regardless of whether the building is sprinklered).
If = Area factor increase due to frontage (percent) as calculated in accordance with Section 506.3.