Existing nonconforming uses. The lawful nonconforming use of a structure or land existing at the time of the adoption or amendment of this chapter may be continued although the use does not conform to the provisions of this chapter; provided, however, that:

Abolishment or replacement. If such nonconforming use is discontinued or terminated for a period of 12 months, any future use of the structure or land shall conform to the provisions of this chapter. When a nonconforming use or structure is damaged by fire, explosion, flood, the public enemy, or other calamity to the extent of more than 50% of its current assessed value, it shall not be restored except so as to comply with the use provisions of this chapter. A current file of all nonconforming uses shall be maintained by the Zoning Administrator listing the following: owner's name and address, use of the structure or land, and assessed value, at the time of becoming a nonconforming use. A nonconforming structure damaged or destroyed by violent wind, vandalism, fire, flood, ice, snow, mold or infestation may be restored in accordance with the provisions of § 62.23(7)(hc), Wis. Stats.[1]

Existing nonconforming structures. A lawful nonconforming structure existing at the time of the adoption or amendment of this chapter may be continued although its size or location does not conform to the lot width, lot area, yard, height, parking and loading, and access provisions of this chapter; however, it shall not be extended, enlarged, reconstructed, moved or structurally altered except when required to do so by law or order or so as to comply with the provisions of this chapter.

Changes and substitutions. Once a nonconforming use or structure has been changed to conform, it shall not revert back to a nonconforming use or structure. Once the Zoning Board of Appeals has permitted the substitution of a more restrictive nonconforming use for an existing nonconforming use, the substituted use shall lose is status as a legal nonconforming use and become subject to all the conditions required by the Zoning Board of Appeals.

Substandard lots. In any residential district, a one-family detached dwelling and its accessory structures may be erected on any legal lot or parcel, provided that such lot or parcel was of record in the County Register of Deeds office before the effective date or amendment of this chapter. Such lot or parcel shall be in separate ownership from abutting lands. If abutting lands and the substandard lot are owned by the same owner, the substandard lot shall not be sold or used without full compliance with the provisions of this chapter. If in separate ownership, all the district requirements shall be complied with insofar as practical but shall not be less than the following: