Section 14. Application of chapter to uncompleted dwellings

1.  The
  provisions of this chapter relating to multiple dwellings erected  after
  April  eighteenth,  nineteen hundred twenty-nine, shall not apply to any
  multiple dwelling for which plans were on file with the department or  a
  permit  to  commence building was issued by the department before August
  ninth, nineteen hundred twenty-nine, and the entire building shall  have
  been completed according to the plans filed with the department, subject
  to  any lawful subsequent amendment thereto, before July first, nineteen
  hundred forty-seven.
    2. No provisions of any part  of  this  section  shall  be  deemed  to
  prohibit  the  amendment  of  any  plans filed and approved before April
  eighteenth, nineteen hundred twenty-nine, if such amendment  would  have
  been  lawful  before  such  date, or if such amendment complies with the
  requirements of this chapter for alterations to buildings of like  class
  and kind existing before April eighteenth, nineteen hundred twenty-nine.
    3. A permit to commence building issued by the department before April
  eighteenth,  nineteen  hundred  twenty-nine,  based upon plans filed and
  approved for a multiple dwelling described in subdivision one, shall  be
  deemed to be in compliance with section three hundred.
    4.  The  provisions  of  this  chapter  relating to multiple dwellings
  erected and occupied as such before April eighteenth,  nineteen  hundred
  twenty-nine,  shall  apply  to  the dwellings described in this section;
  except, however, that unless otherwise  expressly  required  in  article
  three  nothing  in this chapter shall be construed to require any change
  in the plans or occupancy of any such dwelling if it  be  fireproof  and
  the plans therefore when filed were in compliance with the provisions of
  all local laws, ordinances, rules and regulations applicable thereto and
  in  effect  on  April  eighteenth, nineteen hundred twenty-nine, or were
  subsequently amended to comply with such provisions.