Even here, a building permit is required not only for new construction but also for modifications and improvements to existing structures. The permit is issued by the city or municipal engineering department that would include the architectural design and bill of materials for the permit application. My husband's uncle has a house that he expanded without the benefit of a building permit. When a neighbor complained about their house, the uncle had received a notice from the city hall that the extension should be demolished. I don't know if it was already demolished but I guess it has to be within this year.
That's one of the many things I hate about city life. Out of the city no permits are required. Houses do have to conform to State codes but any thing else a homeowner can build as he pleases.