N.Y.C. Admin. Code § 27-465: § 27-465 Railings.

Substantial railings or protective guards of noncombustible materials shall be provided at the perimeter of all parking tiers, except where exterior walls are provided, and around all interior floor openings. Such railings or guards shall be at least three feet six inches high, and shall be designed in accordance with the requirements of subchapter nine of this chapter.