Except as provided in Article 28 of this chapter:
(a) No building shall be moved into an area, erected, reconstructed, added to, enlarged, structurally altered, or maintained, and no building or land shall be used for any purpose except as specifically provided and allowed by the provisions of this chapter with respect to land uses, building heights, yards, area coverage, and lot width, and with respect to all other regulations, conditions, and limitations prescribed by this chapter as applicable to the same zone or sub-zone in which such use, building, or land is located.
(b) While a nonconforming use exists on any lot, no other use of a more restricted classification shall be permitted even though such other use would otherwise be a conforming use.
(§ 8165.1, T.O.O.C., as renumbered by § XIV, Ord. 173-NS, eff. November 5, 1970)