Section 28-105.1. General

It shall be unlawful to construct, enlarge, alter,
  repair, move, demolish, remove or change the use  or  occupancy  of  any
  building  or structure in the city, or to erect, install, alter, repair,
  or use or operate any sign or service  equipment  in  or  in  connection
  therewith,  or  to  erect,  install,  alter,  repair, remove, convert or
  replace any gas, mechanical, plumbing or fire suppression system  in  or
  in  connection therewith or to cause any such work to be done unless and
  until  a  written  permit  therefore  shall  have  been  issued  by  the
  commissioner  in  accordance with the requirements of this code, subject
  to such  exceptions  and  exemptions  as  may  be  provided  in  section
  28-105.4.