All permitted uses in M1-6D Districts, as set forth in Sections 42-11 (Use Group I – Agriculture and Open Uses) through 42-20 (Use Group X – Production Uses) shall comply with the provisions set forth in this Section, inclusive.

1. Residential use#
   
   Residential use shall be permitted in M1-6D Districts only in accordance with the provisions of this Section. For the purposes of this Section, a “qualifying building” shall be any building that existed on April 25, 2011, and which contained at least 40,000 square feet of floor area# on such date.
   1. Residential use as-of-right#
      
      Residential use shall be permitted as-of-right on any zoning lot that, on April 25, 2011, was not occupied by a qualifying building. Such absence of a qualifying building on the zoning lot# shall be demonstrated to the satisfaction of the Department of Buildings.
   2. Residential use by certification#
      
      ​​​​​​​Residential use shall be permitted on a zoning lot that, on April 25, 2011, was occupied by one or more qualifying buildings, only upon certification by the Chairperson of the City Planning Commission that the zoning lot will contain at least the amount of non-residential floor area that existed within qualifying buildings on the zoning lot# on April 25, 2011, provided that:
      1. preservation of non-residential floor area within existing non-qualifying buildings on the zoning lot shall not be counted toward meeting the requirements of this certification; and
      2. floor area from community facility uses with sleeping accommodations shall not be counted toward meeting the requirements of this certification.
         
         However, non-residential floor area converted to residential vertical circulation and lobby space need not be replaced as non-residential floor area.
         
         ​​​​​​​A restrictive declaration acceptable to the Department of City Planning shall be executed and recorded, binding the owners, successors and assigns to provide the amount of non-residential floor area that existed within qualifying buildings on April 25, 2011, on the zoning lot. Such restrictive declaration shall be recorded in the Office of the City Register. A copy of such declaration shall be provided to the Department of Buildings upon application for any building permit related to a change in use from non-residential to residential, or for a new building containing residences.
2. Community facility uses
   
   The regulations for Use Group III that are applicable in M1 Districts shall not apply in M1-6D Districts. In lieu thereof, all  uses listed in Use Group III shall be permitted, except that uses listed in Use Group III(A) shall only be permitted in accordance with paragraphs (1) or (2) of this Section, as applicable.
   
   ​​​​​​​For the purposes of this Section, a “qualifying building” shall be any building that existed on April 25, 2011, and which contained at least 40,000 square feet of floor area on such date.
   1. Uses listed in Use Group III(A) shall be permitted as-of-right on any zoning lot that, on April 25, 2011, was not occupied by a qualifying building. Such absence of a qualifying building on the zoning lot shall be demonstrated to the satisfaction of the Department of Buildings.
   2. Uses listed in Use Group III(A) shall be permitted on a zoning lot that, on April 25, 2011, was occupied by one or more qualifying buildings, only upon certification by the Chairperson of the City Planning Commission that the zoning lot will contain at least the amount of non-residential floor area that existed within qualifying buildings on the zoning lot on April 25, 2011, provided that:
      1. preservation of non-residential floor area within existing non-qualifying buildings on the zoning lot shall not be counted toward meeting the requirements of this certification; and
      2. floor area from community facility uses with sleeping accommodations shall not be counted toward meeting the requirements of this certification.
         
         However, non-residential floor area converted to vertical circulation and lobby space associated with a use listed in Use Group III(A) need not be replaced as non-residential floor area.
         
         A restrictive declaration acceptable to the Department of City Planning shall be executed and recorded, binding the owners, successors and assigns to provide the amount of non-residential floor area that existed within qualifying buildings on April 25, 2011, on the zoning lot. Such restrictive declaration shall be recorded in the Office of the City Register. A copy of such declaration shall be provided to the Department of Buildings upon application for any building permit related to0 a change in use from non-residential to uses listed in Use Group III(A), or for a new building containing such a use.
   3. Commercial and manufacturing uses
      
      The regulations applicable in Special Mixed Use Districts, as set forth in Section 123-21 (Modifications to M1 use regulations) and Section 123-22 (Additional conditions for certain uses), shall apply except that the size limitations for uses listed in Use Group VI, shall not apply.
3. Streetscape provisions
   
   ​​​​​​​For the purposes of applying the underlying ground floor level streetscape provisions set forth in Section 32-30 (STREETSCAPE REGULATIONS) to this Section, the streetscape regulations for C6 Districts shall apply in M1-6D Districts.Ground floor level street frontages along wide streets shall be considered Tier C street frontages. A ground floor level street frontage along any other street shall be considered a Tier B street frontage. Such Tier B provisions shall apply regardless of the zoning district designations on the same or an adjoining block, notwithstanding the exemptions within the definition of Tier B street frontage. Defined terms in this Section include those in Sections 12-10 and 32-301.