On any nonconforming structure, or portion of a structure containing a nonconforming use, work may be done on ordinary repairs or on repair or replacement of nonbearing walls, fixtures, wiring or plumbing; provided, that the cubic content existing when it became nonconforming shall not be increased. Nothing in this section shall be deemed to prevent the strengthening or restoring to a safe condition of any building or part thereof declared to be unsafe by any official charged with protecting the public safety upon order of such official. (Ord. 40, 10-1978, rev. 9-1980)