No permit for clearing a clog
In the State Uniform Construction Code, clearing stoppages falls in the ordinary maintenance class. Permits, inspections and notices to the enforcing agency are all waived for that class, which means a clogged drain stays outside the permit process.
One drain or all of them
A slow drain at a single fixture points to a clog near that fixture. Slow drains at several fixtures, or water backing up in a low drain, point to the main line instead.
A clog that comes back belongs under sewer repair, a faucet or toilet that still misbehaves belongs under fixture repair, and the full list of work is on the homepage.