N.Y.C. Admin. Code § 27-434: § 27-434 Construction.

Heliports shall be permitted only on buildings classified in noncombustible construction group I. All heliport construction above the building roof shall be noncombustible. No openings in the roof shall be permitted in the landing area. Roof openings outside the landing area shall be protected from flammable liquid spillage by four inch curbs and shall be surrounded by metal railings at least three feet complying with the requirements of subchapter nine of this chapter. The landing area shall be enclosed with a substantial metal fence or skirt.