Zoning is a device of land use planning used by local governments. Zoning may be use-based (regulating the uses to which land may be put), or it may regulate building height, lot coverage, and similar characteristics, or some combination of these.
The primary purpose of zoning is to segregate land uses that are thought to be incompatible. In practice, zoning is used to prevent new development from interfering with existing residents or businesses and to preserve the "character" of a community or neighborhood. Zoning is commonly controlled by local governments such as counties or municipalities.
Most zoning systems have a procedure for granting variances (exceptions to the zoning rules), usually because of some perceived hardship caused by the particular nature of the property in question.
Variances enable a property owner to utilize the property in a manner that is not allowed by the local zoning laws. To obtain a variance, a property owner must establish difficulties or "unnecessary hardship" in complying with the zoning law.
The two most common types of zoning variances are a use variance and area variance.
A use variance allows a property owner to use the property for some purpose prohibited by the local zoning laws. When a use variance is sought, the applicant demonstrates "unnecessary hardship" by establishing that:
a. the land cannot yield a reasonable return if used for zoned purposes;
b. the property owner's difficulty is due to unique circumstances and not to general conditions throughout the neighborhood (the hardship must be unique or peculiar to the property for which the variance is sought); and
c. the sought-after use will not alter the essential character of the neighborhood.
Although it is permissible for a municipality to impose conditions on a use variance, the conditions must regulate the property use and not the activities of the applicant (property owner).
An area variance enables the property owner to maintain, build or subdivide on a parcel smaller than that required by the zoning law. To obtain an area variance, the property owner need only show "practical difficulties" in complying with the law.
Even though self-creation of a difficulty is certainly a factor to be taken into account in considering an application for an area variance, it is less significant a consideration in those cases than in applications for use variances. It is not the sole determining factor, and a finding of self-created hardship, normally should not in and of itself justify denial of an application for an area variance.
See New York Times article by Amy Gunderson, "HOME AWAY: When You Need a Zoning Variance", for further discussion on zoning variances.