N.Y.C. Admin. Code § EBC D302: D302 Conversions to a multiple dwelling (MDL 9(2)).

A building, not a dwelling, converted to a multiple dwelling shall comply with the requirements of Sections D302.1 and D302.2, and shall be classified as HAEA (2008+) or HAEB (2008+).

Exceptions:

1. Conversions to CAAs and JARs to the extent otherwise provided for in MDL 277.

2. Reconversions to OL or NL to the extent otherwise provided for in Section D701.1 (MDL 9(6)).

D302.1 Applicable provisions other than height, bulk, open spaces (MDL 9(2)).

A building, not a dwelling, converted to a multiple dwelling, shall thereupon comply with the applicable provisions of this code, including Chapter D3.

D302.2 Height, bulk, open spaces (MDL 9(2), 26).

A building, not a dwelling, converted to a multiple dwelling shall thereupon comply with all applicable requirements for yards and courts under the New York City Zoning Resolution and shall thereupon comply with the floor area ratio provisions of Section 26(3) of the MDL. For the purposes of this section:

1. Conversions that are allowed by the New York City Zoning Resolution to retain existing non-complying yards and courts shall, at a minimum, meet the light and air requirements of Section 277 of the MDL.

2. For buildings converted to multiple dwellings classified as commercial uses under the New York City Zoning Resolution, including but not limited to transient hotels as such term is defined in New York City Zoning Resolution, any courts with required windows opening thereon shall comply with Section D305.1.

3. Buildings granted a lawful variance, authorization, or special permit modifying the requirements of the New York City Zoning Resolution with respect to yards and courts by the board of standards and appeals or the city planning commission shall be deemed in compliance with this section.