All plumbers or steam or gas fitters, before doing work of any kind mentioned in this chapter, except in case of repairing leaks inside of the property line, shall file in the office of the plumbing inspector upon blanks for that purpose an application for a permit, and a plan or sketch of the work to be performed. No such work shall be done in any building without a written permit from the plumbing inspector. (1983 Code § 5-305)