A lawfully preexisting use of a structure or site, which does not conform to the regulations for the district in which it is located, shall be deemed to be a lawful, nonconforming use and may be continued, subject to the following regulations:
A. 
Routine maintenance and repairs may be performed on structures or sites.
B. 
No nonconforming structure shall be moved, altered, or enlarged unless required by law, allowed elsewhere in this code, or unless the moving, alteration or enlargement will result in the elimination of the nonconforming use.
C. 
No structure partially occupied by a nonconforming use shall be moved, altered or enlarged in such a way as to permit the enlargement of the space occupied by the nonconforming use.
(Ord. 89-O-446 § 1; Ord. 09-O-637 § 2)
If a nonconforming use has been changed to a conforming use, or if the nonconforming use of a building, structure or premises is discontinued for the time period specified below, the said use shall be considered abandoned, and said building, structure or premises shall thereafter be used only for a use permitted as an allowed outright use or as a conditional use in the district in which it is located:
A. 
Residential uses in a commercial zoning district: five years, unless the building has been altered to the point that it is no longer suitable as a residence;
B. 
All other uses: two years.
(Ord. 89-O-446 § 1. Formerly 17.120.030; Ord. 90-O-446.B § 3; Ord. 09-O-637 § 2)
If a nonconforming residential or commercial structure is destroyed to any extent, by any cause beyond the owner’s control, it may be rebuilt or replaced by a structure that is no larger than the original structure. Time limits for this replacement shall comply with BMC § 17.120.020.
(Ord. 89-O-446 § 1. Formerly 17.120.040; Ord. 90-O-446.B § 4; Ord. 09-O-637 § 2)
Nothing contained in this code shall require any change in the plans, construction, alteration or designated use of a structure for which a valid permit exists unless work is discontinued and the building permit expires prior to completion.
(Ord. 89-O-446 § 1. Formerly 17.120.050; Ord. 09-O-637 § 2)
Existing structures that do not conform to current standards, including but not limited to setbacks, coverage, and height requirements, can be expanded, but only if all new construction complies with current standards and does not increase the area out of compliance. This provision allows additional stories that meet setbacks to be sited on an existing structure with nonconforming setbacks.
(Ord. 89-O-446 § 1. Formerly 17.120.060; Ord. 09-O-637 § 2; Ord. 10-O-659 § 2)