N.Y.C. Admin. Code § 28-101.4.4: § 28-101.4.4 Reductions of fire safety or structural safety of prior code buildings prohibited.

Notwithstanding any other provision of this code, where the alteration of any prior code building or structure in accordance with a provision of this code would result in a reduction of the fire safety or structural safety of such building, relevant provisions of the 1968 building code shall apply to such alteration unless there is full compliance with those provisions of this code that would mitigate or offset such reduction of fire protection or structural safety. Where the owner, having a choice to elect the 1968 building code or this code, chooses this code, the applicant shall submit a comparative analysis acceptable to the commissioner of the relevant fire safety and structural safety provisions under the 1968 Code and this code, demonstrating that the alteration does not result in a reduction to the fire and life safety of the building.

Exception: The use of automatic-closing by smoke detection for doors serving vertical exit enclosures in accordance with section 713.7 of the New York city building code in a prior code building shall not be deemed to result in a reduction of the fire safety or structural safety of such a building.