The lawful nonconforming use of a structure or land, including, but not limited to, fences, parking and zoning setbacks existing at the time of the adoption or amendment of this chapter may be continued although the use does not conform with the provisions of this chapter. However, only that portion of the land in actual use may be so continued and the structure may not be extended, enlarged, reconstructed, substituted, 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.

If no structural alterations are made, a nonconforming use of a building may be changed to any use permitted in the same use district as that in which the use existing is permitted according to the provisions of this chapter; provided when a use district is changed, any existing, nonconforming use in such changed district may be continued or changed to a use permitted in the same use district as that in which the existing use is permitted; provided all other regulations governing the new use are complied with.

Substitution of new equipment may be permitted by the Board of Zoning Appeals if such equipment will reduce the incompatibility of the nonconforming use with the neighboring uses.

Termination. If such nonconforming use is discontinued or terminated for a period of six months, any future use of the structure or land shall conform to the provisions of this chapter.

Building destroyed by fire. Where a building located in a district restricted against its use has been destroyed by fire or other calamity to the extent of not more than 50% of its fair market value, the same may be rebuilt; but where such a building is destroyed to the extent of more than 50% of its fair market value, a permit may be granted for its reconstruction within 12 months from the date of such fire or other calamity, except any public utility located in a restricted district shall be permitted to rebuild, alter or enlarge in any business or industrial district as the interest of the public demands.

A nonconforming building damaged or destroyed by violent wind, vandalism, fire, flood, ice, snow, mold or infestation after March 2, 2006, may be restored in accordance with the provisions of § 62.23(7)(hc), Wis. Stats.

In any residential district, a one-family detached dwelling and its accessory structures may be erected on any legal lot or parcel 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: