2006 New York Code - Crawl Spaces.

 
    § 27-762 Crawl spaces. (a) Buildings and structures without basements.
  In  buildings and structures constructed without basements, and in which
  the first floor construction does not bear directly  on  the  ground,  a
  space at least eighteen inches high shall be provided directly under the
  floor  beams, girders or sill of the first floor construction. Where the
  floor above such a space is constructed of  wood  or  metal,  the  space
  shall be ventilated by one of the following means:
    (1) At least four widely-distributed ventilating openings, providing a
  total  net  free area of at least one eight-hundredth of the area of the
  crawl space, shall be provided in the foundation walls, and  the  ground
  within  the  crawl  space  shall  be  covered  with  a  vapor barrier in
  durability equivalent to at least fifty-five pounds, roofing  felt  with
  unsealed laps and with a transmission rate of one perm or less. At least
  two  ventilating  openings,  providing a total net free area of at least
  one fifteen-hundredth the area of the crawl space shall be  provided  in
  foundation walls, provided that a vapor barrier with a transmission rate
  of  one perm or less is installed over the entire underside of the first
  floor construction and overlaps the walls.
    (2) Other means acceptable to the commissioner.
    (b) Buildings and structures with basements. No foundation wall  vents
  shall  be  required  where  one side of a crawl space is completely open
  except for structural members, to a basement that has an area  at  least
  equivalent  to  that  of  the crawl space, provided that the basement is
  naturally ventilated  by  openings  complying  with  section  27-749  of
  article  six  of  this  subchapter and having a free openable area of at
  least five per cent of the floor area of the basement.