Section 489-HHH. Extension of time for completion

Where an applicant has
  received a certificate of eligibility but has not completed or will  not
  be  able  to  complete  the  construction  or reconstruction work within
  thirty-six  months,  the  board  shall,  upon  application,  extend   to
  forty-eight  months,  from the time of issuance of such certificate, the
  time for completion of the construction or reconstruction work; provided
  the applicant has completed not less than  two-thirds  of  the  work  as
  specified  in  the certified plans previously filed with the application
  at the time of such application for extension.