The requirements set forth in Section 23-435 (Tower regulations) for any building, or portion thereof, that qualifies as a “tower” shall apply, except as modified in this Section.

1. At any level at or above a height of 85 feet above curb level, a tower shall occupy in the aggregate not less than 30 percent of the lot area of a zoning lot. However, any story located within the highest 15 percent of the tower may cover less than 30 percent of the lot area of a zoning lot provided that the gross area of any such story does not exceed 90 percent of the gross area of that story directly below the highest 15 percent of the tower.
2. At all levels at or above a height of 85 feet from curb level, the minimum required setback of the street wall of a tower shall be at least 15 feet from the street line of Broadway or Columbus Avenue, and at least 20 feet on a narrow street.
3. At least 60 percent of the total floor area permitted on a zoning lot shall be within stories located partially or entirely below a height of 150 feet from curb level.

For the purposes of determining allowable floor area, where a zoning lot has a mandatory 85 foot high street wall requirement along Broadway, the portion of the zoning lot located within 50 feet of Broadway shall not be included in lot area unless such portion contains or will contain a building with a wall at least 85 feet high coincident with the entire street line of Broadway.

For the purposes of determining the permitted tower coverage in Block 3, as indicated on the District Plan in Appendix A of this Chapter, that portion of a zoning lot located within 100 feet of the west street line of Central Park West shall be treated as if it were a separate zoning lot and the tower regulations shall not apply to such portion.