On any nonconforming structure, or on any conforming structure containing a nonconforming use, routine maintenance work may be performed, or repair or replacement of non-bearing walls, fixtures, wiring or plumbing may take place, provided that the value of repair or replacement work during any 12-month period shall not exceed 10% of the replacement cost of the whole structure, and provided further that the square footage of the structure, whether conforming or nonconforming, shall not be increased.
(`83 Code, § 17.48.040) (Ord. 94-03 § 6, 1994)