In M1-1D, M1-2D, M1-3D, M1-4D and M1-5D Districts, vacant floor area in a building originally designed as dwelling units or rooming units may be occupied by a residential use provided that the requirements of either paragraph (a) or (b) are met.

(a)        Residential uses in such buildings may be reactivated as-of-right, provided:

(1)        the floor area has been continuously vacant for two years or more;

(2)        the street line of the zoning lot upon which the discontinued building stands does not exceed 60 feet in length (or, in the case of a corner lot, the lot area does not exceed 6,800 square feet); and

(3)        the zoning lots abutting on both side lot lines and fronting on the same street (or streets, if a corner lot) are occupied by buildings designed for residential use and contain no manufacturing uses.

(b)        Residential uses in such buildings may be reactivated by authorization of the City Planning Commission, provided:

(1)        the floor area has been continuously vacant for two years or more;

(2)        the street line of the zoning lot upon which the discontinued building stands does not form a continuous frontage with vacant land or land with minor improvements whose aggregate length exceeds 60 feet (or, in the case of a corner lot, the lot area does not exceed 6,800 square feet);

(3)        the zoning lot abutting on one side lot line and fronting on the same street is occupied by either:

(i)        a building designed for residential use or a community facility building; or

(ii)        a building originally designed as dwelling units or rooming units for which an application to reactivate residential use in such building has been combined with the subject application;

(4)        25 percent or more of the aggregate length of the block fronts on both sides of the street facing each other is occupied by zoning lots containing community facility buildings or buildings containing residences; and

(5)        the Commission finds that:

(i)        reactivating the residential use will not adversely affect manufacturing or commercial uses in the district; and

(ii)        such residential use will not be exposed to excessive noise, smoke, dust, noxious odor, or other adverse impacts from manufacturing or commercial uses.

In granting such authorization, the Commission may prescribe additional conditions and safeguards as the Commission deems necessary.

The number of dwelling units permitted in such reactivated building containing residences shall not exceed the greater of the number of lawful dwelling units last recorded by the Department of Buildings, or one dwelling unit for every 675 square feet of total net residential floor area as defined in Section 28-02 (Definitions).

No dwelling unit shall be permitted on or below a story occupied by a commercial or manufacturing use.

Residential uses in M1-D Districts may enlarge pursuant to the regulations of Sections 52-46 (Conforming and Non-conforming Residential Uses in M1-1D Through M1-5D Districts) or 42-321 (Residential uses in M1-1D through M1-5D Districts) as applicable.