No nonconforming use except as provided in Section 17.52.650 shall be enlarged or extended so as to occupy a greater area of land or of a building than occupied at the time it became a nonconforming use. Except as otherwise provided in Section 17.52.650 of this chapter, no nonconforming building shall be enlarged, extended or structurally altered unless the entire building and the use thereof is so changed as to be conforming in every respect. Except as otherwise provided in Section 17.52.660, no nonconforming use shall be changed to a different nonconforming use. The provisions of this section shall not apply to dwellings in the A district that are nonconforming solely because they were not subject to site development review pursuant to Section 17.06.090 of this title. (Prior gen. code § 8-62.3)