In accordance with the provisions of Section 91-31 (Street Wall Regulations), setbacks are required for any portion of a building or other structure that exceeds the maximum base heights specified for the applicable street in Section 91-31.

Required setbacks shall be provided at a height not lower than any minimum base height or 60 feet where none is specified and not higher than any maximum base height specified for the applicable street in Section 91-31. The depth of the setback shall be determined by the lot area of the zoning lot, as shown in the following table:

REQUIRED DEPTH OF SETBACKS

For "Type 1" and "Type 2A and 2B" street walls, the required setbacks shall be measured from the street line.

For "Type 3" street walls, the required setbacks shall be measured from a line drawn at or parallel to the street line so that at least 70 percent of the aggregate width of street walls of the building at the minimum base height are within such line and the street line.

For all other street walls, the required setbacks shall be measured from a line drawn at, or parallel to, the street line so that at least 50 percent of the aggregate width of street walls of the building at the minimum base height are within such drawn line and the street line. However, setbacks are not required for street walls fronting upon the major portion of a bonused public plaza.

For buildings within the Historic and Commercial Core as shown on Map 1 in Appendix A, any building or portion of a building may be located within the required setback area beneath a sky exposure plane that rises from a height of 100 feet above the street line over the zoning lot at a vertical distance of six to a horizontal distance of one.