Floor area regulations are set forth in Section 23-21 for R1 through R5 Districts and Section 23-22 for R6 through R12 Districts. Special allowances for multi-family buildings are set forth in Section 23-23. Special rules governing certain areas are set forth in Section 23-24. 

For zoning lots with buildings containing multiple uses or multiple buildings with different uses, inclusive of residences subject to different floor area ratios, the maximum floor area ratio for each use shall be as set forth in the applicable provisions of this Section, inclusive, or as provided in the respective floor area provisions of another Chapter of this Resolution. The total of all such floor area ratios shall not exceed the greatest floor area ratio permitted for any such use on the zoning lot. 
 
Where floor area in a building is shared by multiple uses, the floor area for such shared portion shall be attributed to each use proportionately, based on the percentage each use occupies of the total floor area of the zoning lot, less any shared floor area.

Where a floor area bonus established through another Section of this Resolution applies to a zoning lot containing residences, the residential floor area ratio used to calculate the maximum permitted floor area bonus shall be the maximum floor area ratio permitted for such zoning lot pursuant to this Section, depending on whether the zoning lot is a qualifying residential site or the zoning lot contains qualifying affordable housing or qualifying senior housing#.