While it seems like they have been with us forever, zoning ordinances are relatively recent in origin. Many local municipalities began to adopt zoning ordinances in the middle of the twentieth century, typically in the 1950’s and 1960’s. Prior to that time there was little organized regulation of land uses.
When zoning ordinances were first adopted they were applied to properties that were already being used for many different uses, often inconsistent in character. For example, you could find a residential structure and use adjacent to an auto repair garage. Take a ride through some of the older boroughs in the Commonwealth and you can still see a variety of incongruous uses within the same block. Zoning ordinances changed all of that by imposing different zoning districts for different types of uses in an effort to promote harmony and consistency.
Uses that were not consistent with a newly enacted zoning ordinance were rendered “nonconforming.” Zoning ordinances typically provide that any lawful use or structure which existed on the date the zoning ordinance took effect would continue as a “lawful nonconforming use” or “lawful nonconforming structure,” subject to a right of continued use in the future. If zoning ordinances did not allow existing nonconforming uses to continue they would be rendered unconstitutional, either as an unlawful taking of property without compensation or as an ex post facto law. This principle of continued right to use a nonconforming property is commonly called “grandfathering.”
Most zoning ordinances also allow lawful nonconforming uses and structures to be expanded (either in size or intensity of use) up to a certain point, typically 25%. Thus, a business in a nonconforming building can expand to a limited degree.
Nonconforming uses and structures are also subject to special rules in the event they are destroyed or discontinued. For example, if a nonconforming structure is totally destroyed by fire most zoning ordinances require that any new structure be built in compliance with existing zoning regulations. The benefit of the nonconforming use is thus lost. If a structure is partially destroyed, it can typically be rebuilt to the original nonconforming standard provided that the level of destruction does not exceed a certain percentage, typically around 75%.
Most zoning ordinances provide that if a lawful nonconforming use or structure is abandoned or discontinued for a continuous period of time, typically 1 year, any subsequent use of the property or structure must be in conformity with the zoning ordinance. Whether a nonconforming use or structure has been “abandoned” within the meaning of the zoning ordinance is typically a matter of the owner’s intent and is often a hot topic of debate with the municipal government.