(1) Ordinary maintenance of a nonconforming structure which includes minor interior and exterior repairs and incidental alterations is permitted. Minor maintenance and repair may include, but are not limited to painting, roof repairs and replacement, plumbing, wiring, mechanical equipment replacement, and weatherization. Incidental alterations may include construction of nonbearing walls and partitions. Ordinary maintenance and incidental alterations shall not exceed 20 percent of the value of the building at the time of repair or alteration;

(2) No building damaged by fire or other causes to the extent of more than 50 percent of the assessed value of the structure as determined by the records of the Franklin County Assessor shall be repaired or rebuilt, except multifamily units previously authorized by building permit in any residential zoning district may be rebuilt under the following conditions:

(3) Any structure or portion thereof declared unsafe by the Building Official may be restored to a safe condition and continue as a nonconforming use, unless such repairs exceed 50 percent of the assessed valuation of the structure as determined by the records of the Franklin County Assessor, except multifamily units previously authorized by building permit in any residential zoning district may be rebuilt under the following conditions: