2023 New York Laws › MDW - Multiple Dwelling › Article 7 - Tenements › Title 1 - Light and Air › 218 - Alterations.

§  218.  Alterations.  1. Any non-fireproof tenement erected after May
  fifteenth, nineteen hundred two, having apartments extending from street
  to yard and having one or more outer courts on a side lot line four feet
  or more in width or inner courts which alone or together with  adjoining
  courts  are  eight  feet  or more in width and twelve feet six inches or
  more in depth, may be altered into  apartments  opening  either  on  the
  street  or  the  yard,  provided  all  such altered apartments also have
  windows opening on such a court. All such altered  apartments  shall  be
  provided  with  a  second  means  of  egress  as required by section two
  hundred thirty-one. The entrance and stair halls of such tenement  shall
  be fire-retarded.
2.  No  room  in  the  cellar  or  basement  of  any tenement shall be
  constructed or altered to be occupied for living purposes unless all  of
  the  conditions  of  section  thirty-four  and  of  subdivision eight of
  section twenty-six in regard to multiple dwellings erected  after  April
  eighteenth, nineteen hundred twenty-nine, are complied with, except that
  the  minimum  depths  of  yards  and  courts prescribed for tenements in
  subdivision one of section two hundred twelve shall be  substituted  for
  the minimum depths referred to in section thirty-four.
3.  Any  additional  room or hall constructed or created in a tenement
  shall comply in  all  respects  with  the  provisions  of  this  article
  respecting  rooms  or halls in tenements erected after April eighteenth,
  nineteen hundred twelve, except that in any tenement erected after April
  fourteenth, nineteen hundred three, such rooms or halls may  be  of  the
  same height as the other rooms or halls on the same story.
4.  The  number  of  apartments or suites of rooms on any story in any
  tenement erected after April  twelfth,  nineteen  hundred  one,  may  be
  altered  so  as  to  increase  or  decrease  the  number of living rooms
  provided such dwelling shall conform with the applicable  provisions  of
  sections two hundred thirty-five and two hundred thirty-six.
5.  If  the  number  of  apartments  or suites of rooms in any old-law
  tenement is increased, the entrance hall and both sides of the walls  of
  the  stair halls adjoining the altered apartment shall be fire-retarded,
  the stairs shall extend to the roof and there shall be no inside  stairs
  from  the  entrance  story  to a cellar, or to a basement or other story
  below the entrance story. However, such inside stair  may  be  permitted
  provided such stair is constructed of incombustible material, has closed
  risers, is enclosed between the entrance story and the next lowest story
  with  fireproof  materials having a standard fire-resistive rating of at
  least three hours, and has fireproof doors and door  assemblies  at  the
  top  and bottom with the doors and door assemblies at the top and bottom
  with the doors self-closing. The soffit of any stair  immediately  above
  an  inside  cellar  stair  shall be fire-retarded and the jib partitions
  enclosing such cellar stair at the first story shall be of incombustible
  material or fire-retarded on both sides with materials having a standard
  fire-resistive rating of at least one hour.
6. If any old-law tenement shall be so  altered  as  to  increase  the
  number  of  rooms  therein  by one-third or more, or if such tenement is
  increased both  in  number  of  rooms  and  in  height  and  after  such
  alteration  is more than four stories or parts of stories above the curb
  level, or if such tenement is  over  three  stories  in  height  and  is
  combined  with  another  old-law  tenement  and the combined area on any
  story exceeds three thousand square  feet,  the  stair  halls,  entrance
  halls  and  other  public  halls  of the whole dwelling shall be made to
  conform to the requirements of subdivision two of  section  two  hundred
  thirty-three  and  sections  two  hundred  thirty-four  to  two  hundred
  thirty-eight inclusive, except that such  combined  tenements,  if  over

  three  stories  in  height,  shall have in the roof a fireproof bulkhead
  with a fireproof self-closing door.
7.  In  lieu  of fire retarding required under subdivision five, there
  may be installed in public halls an automatic dry pipe valve system  or,
  where  halls are heated, an automatic wet pipe system. Where a sprinkler
  system is installed it shall be equipped on each  story  with  heads  in
  such  number and spaced to protect the complete area of the public halls
  and stairs and shall be constructed, located and arranged on every stair
  and entrance hall and in every closet opening therefrom in such a manner
  as the department may require. Such sprinkler system shall be maintained
  continuously in good repair and serviceable condition.