2006 New York Code - Bulkheads.

 
    §  104.  Bulkheads. 1. Every stair, fire-stair and fire-tower required
  by this chapter to extend to the level of the roof  or  to  any  terrace
  formed  by a setback shall extend to and through a fireproof bulkhead or
  other fireproof enclosure in  such  roof  or  terrace  approved  by  the
  department.    Such bulkhead or enclosure shall give unobstructed access
  at all times to such roof or terrace by means of a  fireproof  door  and
  door  assembly  with  the  door self-closing. Such a door shall never be
  self-locking and shall be fastened on the inside by movable bolts, hooks
  or a lock which does not require a key to open from the  inside  of  the
  dwelling. Stairs to a bulkhead or enclosure shall have a handrail.  When
  a  dwelling  has a pitched or sloping roof with a pitch or slope of more
  than fifteen degrees, no bulkhead or  stair  leading  thereto  shall  be
  required.
    2.  The  roof  of any penthouse may for the purpose of this section be
  deemed part of the main roof if  unobstructed  access  be  provided  and
  maintained  between  all  required  fire-stair landings on the main roof
  adjoining such penthouse, on the roof of such penthouse and on the  roof
  of any other penthouse extending above such main roof. Such unobstructed
  access,  where horizontal, shall be by means of a passage at least three
  feet in clear width. It may include one  or  more  stairs  necessary  to
  provide  access  from any penthouse roof to any main roof adjoining such
  penthouse. Such stairs shall conform to all the requirements of  section
  fifty-three  for stairways of fire-escapes.  There shall be a passageway
  at least four feet in clear width between such stairs  and  the  parapet
  wall or guard railing of the main roof.