From the comments regarding the right way to report unpermitted work in San Francisco:

“I’ve seen plenty of rehab projects that were dressed up for inspection, and converted after sign off from [the Department of Building Inspection] – for example, a “powder room” with a disallowed shower stall hidden behind a wall of sheet rock. Inspector signs off, contractor knocks down the sheet rock, and *voila* we have an illegal full bath, with the appearance of being permitted and approved by the city.”

What’s The Right Way To Rat Out A Neighbor And Report Illegal Work? [SocketSite]