A nonconforming use is generally defined as a land use or structure that was legal when established but does not conform to the standards of the current zoning ordinance. The term “nonconforming use” actually covers several situations, including nonconforming uses, lots and structures.
Preexisting land uses that do not conform to current zoning are not favored. The ultimate goal of zoning is to achieve uniformity of property uses within each zoning district. At the same time, landowners have made investments in their businesses and buildings, and it would be unfair -- not to mention illegal in some states -- to require immediate termination or removal. Rather than require the immediate elimination of these preexisting uses, the zoning ordinance will outline a set of conditions for the continued existence of nonconforming uses.
Although state courts apply different interpretations to local zoning codes regarding nonconforming uses, the expansion, enlargement or intensification of a nonconforming use in almost all cases can be regulated or prohibited.
Resumption of a nonconforming use or structure after it has been destroyed may be prohibited in some states. In other states the right to reestablish the nonconforming use exists. Zoning ordinances traditionally have set a specific threshold-- for example, a percentage of assessed value -- for defining what constitutes destruction, and courts generally defer to the stated threshold. Again, the principle is to allow landowners to continue to reap the benefits of investments made in their properties. If those investments have been destroyed, however, the community may or may not have an obligation to allow a landowner to reinvest in a use prohibited by current zoning.
To prevent nonconforming uses from becoming blighted properties, zoning codes generally do allow for routine maintenance and repair, so long as such activities do not constitute expansion or enlargement.
Once a nonconforming use has been abandoned, its resumption can be prohibited. Most ordinances state a time period, usually six months to a year, that creates a presumption of abandonment if the property is not used for that period. Some states do not allow just a passage of time to establish abandonment. The issue of what constitutes abandonment is one that is generally the subject of much state court case law, with some courts requiring that an “intent to abandon” be shown before the nonconforming use is considered to be terminated. The intent to abandon may be something like a list of criteria, in the zoning ordinance, from which “abandoned” is established from a preponderance of facts about the particular situation.
Gary D. Taylor, Iowa State University