2006 New York Code - Construction.

 
    §  27-521.3  Construction.  (a)  Atriums  may  be  constructed only in
  buildings in noncombustible construction groups 1-A, 1-B and 1-C.
    (b) An atrium shall be fully enclosed except that openings of any size
  into the two lowest levels of an  atrium  shall  be  permitted  if  such
  openings  are provided with opening protectives having a fire-resistance
  rating of  at  least  one  and  one-half  hours  or  are  provided  with
  sprinklers no more than six feet apart.
    (c) The minimum horizontal clear dimension of an atrium shall be forty
  feet,  provided,  however  that  this dimension can be reduced to twenty
  feet where sprinkler spacing on the  occupied  side  adjacent  to  glass
  panels  authorized  by  subdivision  (d) of this section is no more than
  four feet or the minimum atrium area is twelve hundred square feet.
    (d)  Atrium  enclosing  walls  shall  be  of   at   least   two   hour
  fire-resistant  construction  or  of  glass that is wired, laminated, or
  tempered and is provided with sprinklers on the occupied side spaced  no
  more  than  six feet apart, except as otherwise permitted by subdivision
  (c) of this section.