Section 28-112.9.2. Lien

All such unpaid amounts shall constitute a lien upon
  the  land  and  building  upon, or in respect to which, such inspection,
  reinspection, examination or service was performed or permit issued when
  the amount thereof shall have been definitely computed as a statement of
  account by the department and the department shall file  such  statement
  with  the  department  of  finance  for  entry  in  the  records of such
  department against the premises. Such lien shall have  a  priority  over
  all  other  liens  and  encumbrances  except  for  the lien of taxes and
  assessments. However, no lien created pursuant to this section  28-112.9
  shall  be  enforced  against  a  subsequent  purchaser  in good faith or
  mortgagee in good faith unless the requirements  of  section  28-112.9.1
  are satisfied.