Section 27-351. Finish flooring and floor coverings

Finish flooring and
  floor coverings shall comply with the following:  (a)  In  buildings  or
  spaces  classified in occupancy group A and in all exits except those in
  buildings of construction  group  II-E,  finish  flooring  shall  be  of
  noncombustible  material  and except as otherwise provided for stairs in
  subdivision (h) of section 27-375 of article five of subchapter  six  of
  this chapter.
    (b) Flooring in buildings or spaces of construction group I. Except as
  provided  in subdivision (a) of this section combustible finish flooring
  may be used in buildings or spaces of construction group I when cemented
  directly to the top surface of  noncombustible  floor  construction,  or
  attached  to  combustible  or  noncombustible sleepers. When attached to
  sleepers, the space between the noncombustible  floor  construction  and
  the  bottom  of  flooring  shall  be  solidly filled with noncombustible
  material to within one-quarter  inch  of  the  flooring,  or  the  space
  between  the sleepers under the flooring shall be firestopped into areas
  of not more than twenty square feet, and provided further that  no  open
  spaces  shall  extend  under  or  through fire divisions or through fire
  separations. Combustible insulating or sound absorbing boards  not  more
  than  one-half  inch  thick and having a flame-spread rating not greater
  than class C may be used when attached directly to noncombustible  floor
  construction and covered with finish flooring.
    (c)  Flooring  in buildings or spaces of construction group II. Except
  as provided in subdivision (a)  of  this  section,  finish  flooring  in
  buildings  or  spaces  of  construction  group  II may be of combustible
  material.
    (d) Floor coverings.
    (1) Exits. Where exits are required under any provision of this  code,
  carpets  and  carpet  assemblies  shall  not be installed in such exits,
  except that wool  carpeting  may  be  installed  in  lobby  areas,  exit
  passageways and convenience stairs.
    (2)  Flammability  requirements.  The requirements of this subdivision
  shall apply to carpets and carpet assemblies only when used as  a  floor
  covering  (for  requirements pertaining to carpets and carpet assemblies
  used as interior finishes, see section  27-348  of  this  article).  For
  purposes  of  this  subdivision,  carpeting assemblies shall include the
  carpet, its underlay, and adhesives which when  tested  as  a  composite
  shall be representative of the proposed installation.
    a.  Pill  test.  All  carpets and underlayments shall pass a methanine
  pill test in accordance with the requirements of reference  standard  RS
  5-20.
    b.  Critical radiant flux test. Carpets and carpet assemblies shall be
  tested by the method for critical radiant flux in  accordance  with  the
  requirements of reference standard RS 5-20. The time frame for such test
  shall be at least a fifteen minute exposure.
    1.   Carpets  and  carpet  assemblies  representative  of  the  actual
  installation on floors of  corridors,  shall  have  a  minimum  critical
  radiant flux of 0.5 watts per square centimeter (W/cm{2}).
    2.   Carpets  and  carpet  assemblies  representative  of  the  actual
  installation on floors of general areas shall have  a  minimum  critical
  radiant flux of 0.4 W/cm{2}.
    c.   Smoke   developed   ratings.   Carpets   and   carpet  assemblies
  representative of the actual installation  on  floors  of  corridors  or
  general  areas shall be tested for smoke developed ratings in accordance
  with the requirements of reference standard RS 5-20. The smoke developed
  ratings in either the flaming or no-flaming mode shall not exceed  three
  hundred within the first four minutes of the test.

    d.  The manufacturer of the carpets and carpet assemblies shall submit
  a  certificate  from  an  independent  laboratory  acceptable   to   the
  commissioner  pursuant to section 27-131, showing the complete test data
  results, prior to final acceptance. The certification shall  state  that
  the  material  is  treated  for  fire  resistance and shall indicate the
  service life of the treatment or that the material  is  inherently  fire
  resistant  by  virtue  of  its  construction, chemical properties and/or
  composition. Materials which are not inherently fire  resistant  may  be
  used only when the certified fire resistant service life exceeds that of
  the  planned  service  life  of  the  carpets and carpet assemblies with
  consideration being given to cleaning, traffic, and other conditions  of
  use which may affect the treatment.