Section 26. Egress from dwellings

In every such dwelling three stories or
  more in height there shall be from each story at least  two  independent
  means  of  egress accessible to each apartment or suite. The first means
  shall open into a public hall connected  with  a  stair  affording  safe
  access  to  a  street,  or  to  a  yard,  court  or passageway affording
  continuous, safe and unobstructed access to a street. The  second  means
  shall  be  directly  to  a  fire-escape  or to an enclosed stair without
  passing through the first means,  except  that  where  the  first  means
  includes  an  interior  stair which is closed off at each floor level by
  fire-retarded construction with a fireproof self-closing  door  therein,
  the  second  means  may  be another such interior stair or a fire-escape
  directly accessible on the same story from a public hall therein whether
  or not such public hall is also a part of the first means provided  such
  fire-escape  is  not  a  wire,  chain,  cable,  vertical  ladder or rope
  fire-escape. In lieu of a second means of egress a sprinkler system  may
  be installed in the public halls and stairs.
    Except  as required by the provisions of article four of this chapter,
  the second means of egress shall not be required in a multiple  dwelling
  of fireproof construction, six stories or less in height, erected before
  July  first,  nineteen  hundred  fifty-two,  if  the egress arrangements
  thereof complied with requirements of law applicable  at  the  time  the
  dwelling was erected.