N.Y.C. Admin. Code § 27-452: § 27-452 Construction.

The street floor construction of group 1 public garages shall have at least a two hour fire-resistance rating. Where openings are provided in the floor of any public garage, they shall be protected by railings complying with the requirements of subchapters nine and ten of this chapter, with a curb or ramp at least six inches high above the floor. All floors shall be concrete or equivalent noncombustible material. Columns in parking areas shall comply with the provisions of section 27-559 of article three of subchapter nine of this chapter.