R6  R7  R8  R9  R10  R11  R12

In the districts indicated, the following additional regulations shall apply:

1. Existing buildings may be vertically enlarged by up to one story or 15 feet without regard to the street wall location requirements of Section 23-431.
2. On through lots which extend less than 190 feet in maximum depth from street to street, the street wall location requirements of Section 23-431 shall be mandatory along only one street frontage.
3. On corner lots, or portions thereof, the street wall location requirements of Section 23-431 shall be mandatory along only one street frontage. Where one of the street frontages bounding the corner lot is a wide street and the other a narrow street, the street wall location rules shall be applied along the wide street frontage;
4. The street wall location and minimum base height provisions of Sections 23-431 and 23-432, respectively, shall not apply along any street frontage of a zoning lot occupied by buildings whose street wall heights or widths will remain unaltered.
5. The minimum base height provisions of Section 23-432 shall not apply to buildings, or portions thereof, that are developed or enlarged and do not exceed such minimum base heights.
6. For any zoning lot located in a Historic District designated by the Landmarks Preservation Commission, the street wall location and minimum or maximum base height regulations of Section 23-43, inclusive, or as modified in any applicable Special District, may be modified as follows:
   1. The minimum base height of a street wall may vary between the applicable minimum set forth in Section 23-432, and the height of the street wall of an adjacent building before setback, if such height is lower than the minimum base height; and
   2. The maximum base height of a street wall may vary between the applicable maximum set forth in Section 23-432, inclusive, and the height of the street wall of adjacent building before setback, if such height is higher than the maximum base height.
7. Where a continuous sidewalk widening is provided on the zoning lot, along the entire block frontage of a street, the boundary of the sidewalk widening shall be considered to be the street line for the purposes of applying the provisions of Section 23-431, but such widening may be included in the setback reductions permitted pursuant to paragraph (a) of Section 23-433.