N.Y.C. Admin. Code § 27-111: § 27-111 Continuation of lawful existing use.

The lawful occupancy and use of any building, including the use of any service equipment therein, existing on the effective date of this code or thereafter constructed or installed in accordance with prior code requirements, as provided in section 27-105 of article one of this subchapter, may be continued unless a retroactive change is specifically required by the provisions of this code.