2006 New York Code - Alterations Under Thirty Percent Of Building Value.

 
    § 27-117 Alterations under thirty percent of building value. Except as
  otherwise provided for in sections 27-120 and 27-121 of this article, if
  the cost of making alterations in any twelve month period shall be under
  thirty  percent  of  the  value  of  the building, those portions of the
  building altered may,  at  the  option  of  the  owner,  be  altered  in
  accordance  with the requirements of this code, or altered in compliance
  with the applicable laws in existence prior to December sixth,  nineteen
  hundred  sixty-eight, provided the general safety and public welfare are
  not thereby endangered.