That such alteration, enlargement, or reconstruction does not exceed twenty-five percent of the value of the existing building;

That floor area shall not be increased over ten percent of the total existing floor area of the building, except that this limitation shall not apply to single-family residences in an area zoned for single-family use.

That the alteration, enlargement, or reconstruction shall not increase any discrepancy between existing conditions and the regulations prescribed by code;

That the planning director shall determine that added safety, reduction of fire hazard, aesthetic improvement, or closer conformity to surrounding conforming structures shall be achieved.

Repairs or interior alterations which do not enlarge a nonconforming building or structure may be made; provided, however, that any nonconforming building or structure destroyed by fire, explosion, act of God, natural calamity, or act of the public enemy to a greater extent than fifty percent shall be removed or reconstructed in conformance to zoning regulations. The extent of damage shall be determined by the ratio of the estimated cost of restoring such building or structure to its prior condition, before damage, to the estimated cost of duplicating the entire structure as it existed prior thereto.

If such damage is fifty percent or less, a nonconforming building or structure may be restored providing such restoration is commenced within one hundred eighty days and diligently pursued to completion.

No nonconforming use shall be resumed, reestablished, or reopened after it has been abandoned, discontinued, or changed to a conforming use. A nonconforming use shall be deemed to have been discontinued or abandoned when such has ceased to be used, operated, or exist as a nonconforming use for a period of one hundred eighty days. Such date for commencement of the one-hundred-eighty-day period shall be established upon lapse of city business license, lapse of State Board of Equalization permit, or date noted by a city official with proper site verification of abandonment or discontinuance duly documented or any other competent evidence tending to prove such cessation of use.

Notwithstanding any provisions of subdivision 1 of this subsection gasoline service stations are hereby declared to be a special class of land use and shall be deemed to be abandoned and discontinued after a period of sixty days determined as to date of commencement as for other nonconforming uses.

Nonelectrical signs and advertising activities listed as prohibited under Chapter 17.18, sixty days,

Electrical signs and advertising devices, listed as prohibited under Chapter 17.18, one hundred eighty days,

Off-premises advertising signs not advertising business, product, or service supplied on the property upon which it is located and having a value less than five hundred dollars, one year,

Billboards or outdoor advertising structures having a value greater than five hundred dollars and not having been approved by a prior conditional use permit or variance, three years,

On-premises advertising signs advertising a business, product, or service on the property on which they are located and which are nonconforming due to area, height, or other pertinent zoning regulations without a prior approved conditional use permit or variance, five years. Monument signs conforming to the provisions of this code prior to the adoption of Ordinance No. 565 shall be exempt from this provision;