Sec. 9-4.2705.  Nonconforming uses of nonconforming buildings.
   (a)   The nonconforming use of a nonconforming building or structure shall not be expanded or extended to portions of such building or structure which were not in use at the time the use became nonconforming.
   (b)   The nonconforming use of a nonconforming building or structure may be changed to another use of the same zoning classification
provided no exterior structural alterations are made therein.
   (c)   The nonconforming use of any nonconforming building may be changed to any use which is permitted in a more restrictive zone, except no residential use shall be permitted to replace nonconforming uses within commercial or industrial zones.  The sequence of such zones, the first being the most restrictive and the last being the least restrictive, is as follows: R-1, R-O, R-E, R-A, R-2, H-P-D, R-P-D, R-3, T-P-D, C-O, C-1, C-2, C-3, C-4, M-1, and M-2.
   When the zoning use of a nonconforming building is changed to a use which is permitted in a more restrictive zone, such nonconforming building shall not thereafter be reoccupied by a use which is permitted only in a less restrictive zone.
(§ 8162.6, T.O.O.C., as amended by § 14, Ord. 89, and §20, Ord. 126, renumbered by § XIV, Ord. 173-NS, eff. November 5, 1970, as renumbered and amended by § 10, Ord. 1230-NS, eff. April 18, 1995)