Zoning 101

Zoning and Development Glossary

Note: We’re developing illustrations for some key definitions in this glossary. Check back later to see them. As well, if you have any suggestions to add to the glossary, please let us know in the contact form at the bottom of the page.

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

A

An Accessory Dwelling Unit (ADU) is a smaller, separate home located on the same lot as a single-family home that is being used as primary residence. Can be physically attached to the primary dwelling unit but must have its own entrance. Commonly called an in-law suite, granny flat, etc. Not to be confused with an Affordable Dwelling Unit (see: Inclusionary Zoning).

An Accessory Use is a secondary use of a property that is incidental and subordinate to the primary use. The accessory use is typically located on the same lot as the primary use and is related to it in terms of functionality. For example, a garage, shed, or garden could be considered an accessory use to a primary residential use.

B

The Board of Zoning Appeals (BZA) is a local citizen board appointed by the Circuit Court to hear petition requests for special exceptions and variances requests.

By-right Development is development of a property that already conforms to existing zoning and building code, and so does not require special approval.

C

A Comprehensive Plan (sometimes shortened to “comp plan,” or called a “master plan” or “general plan) is a document produced by a local government that expresses its desires for the future development of communities in its jurisdiction. Comprehensive plans cover many areas, such as housing, land use, transportation, utilities, recreation, public spaces, urban design, and more. Comprehensive plans contain a future land use map, which serves as the basis for amendments to the locality’s zoning code.

A Condominium, usually shortened to Condo, is an arrangement where units of a multi-family building such as apartments or townhouses can be sold individually. Owners in a condominium arrangement own their individual units as well as a share of the common spaces in the building or complex through a legal entity called a condominium association. Condominium arrangements may also be used for single-family detached housing developments in some cases, such as in gated communities.

D

A Duplex is a type of residential building that consists of two separate housing units or apartments, typically sharing a common wall or floor.

E

An Easement is a legal right to use someone else’s land for a specific purpose. It’s a form of nonposessory interest that allows the easement holder access to or through another person’s property without conferring ownership. For example, utility easements allow companies to install and maintain infrastructure like electricity lines.

The Entitlement Process is the legal process through which a local government grants permission for a development that does not conform with the existing zoning. These entitlements can take the form of Special Use Permits, Rezonings, or Variances.

Euclidean Zoning, also called conventional zoning or single-use zoning, is a method of land use regulation that divides municipalities into residential, commercial, and industrial zones or districts. Each has a specific set of regulations dictating what type of buildings and activities can occur within them. The name “Euclidean” comes from a landmark U.S. Supreme Court case, Village of Euclid, Ohio v. Ambler Realty Co., which affirmed the constitutionality of this type of zoning in 1926.

The primary purpose of Euclidean zoning is to prevent uses that are thought to be incompatible from interfering with each other. For instance, factories are separated from residential areas to protect homes from noise, pollution, and traffic associated with industrial uses. While it has been widely used for organizing towns and cities, Euclidean zoning has also been criticized for contributing to urban sprawl and reinforcing socioeconomic and racial segregation.

Exclusionary Zoning is the practice of using zoning regulations and land use policies to exclude certain types of housing or specific groups of people from residing in a particular area.

F

Floor Area Ratio (FAR), also known as Floor Space Index (FSI) or Floor Space Ratio (FSR), is a calculation used in urban design and zoning regulations to determine the maximum allowable floor area of a building in relation to the size of the land on which it is located. It is a ratio that represents the total floor area of a building divided by the area of the plot of land on which the building is constructed.

Form-based Code is a method of regulating land development to achieve a specific urban form. This type of zoning focuses more on the physical form and character of buildings and less on land use. Form-based codes address: 

• the relationship between building facades and public spaces
• the form and mass of buildings in relation to one another
• the scale and types of streets and blocks

Unlike traditional zoning regulations that segregate land uses, form-based codes aim to integrate different uses and create mixed-use neighborhoods. This approach is intended to make cities more walkable, diverse, and attractive.

A Fourplex, also known as a quadplex, is a type of residential building that contains four separate housing units or apartments. Typically arranged in two floors, with two units on each floor.

G

H

In real estate, Highest and Best Use refers to the most profitable, legally permitted, and physically possible use of a piece of property. This use should be sustainable in the long term and generate the highest economic value or the greatest benefit to its owner.

In the context of zoning, “Highest and Best Use” refers to the most profitable use of a property that is allowed under the existing zoning laws. Zoning laws can influence a property’s “Highest and Best Use” by limiting the types of activities or developments that can take place on a property.

I

Inclusionary Zoning is a policy implemented by local governments to promote or require the inclusion of affordable housing within residential developments. It awards incentives to residential developments that set aside units for low-income households. Such policies may require affordable set-asides in certain cases. In Virginia, these laws are known as Affordable Housing Dwelling Unit (ADU or AHDU) ordinances.

J

K

L

Lot Coverage is the portion of a property or plot of land that is covered by structures. It is often expressed as a percentage of the total lot area. For example, if a 1,000-square-foot building sits on a 4,000-square-foot lot, the lot coverage is 25%.

Maximum lot coverage is a common regulation in zoning ordinances. Among other things, it is used to: 

• control the size and placement of buildings
• ensure adequate open space
• limit overdevelopment
• manage stormwater runoff

Lot Frontage is the length of a property that borders a public or private street, road, or thoroughfare. It is essentially the boundary of a lot that runs along the street. This is the side of a property where the main entrance is typically located and where the property is accessed.

Lot frontage regulations are common in residential zoning. They often specify a minimum lot frontage for a parcel of land to be considered a legal building lot. This ensures that all parcels of land have adequate access to public streets and services. For example, a zoning ordinance might require that residential lots have a minimum frontage of 50 feet. This means that to be buildable, a lot must have at least 50 feet bordering a street.

M

A Manufactured Home, historically also called a mobile home or trailer, is a single-family home that is assembled in a factory and transported to its final location on a truck. Manufactured homes are usually installed in “parks,” where a private landowner provides standard-size concrete pads which they rent out to homeowners. Due to their small size and efficient factory production, manufactured homes are some of the most affordable homes available.

The terms “mobile home” or “trailer” are no longer technically accurate to the way manufactured homes work today; they are much larger than standard freight trailers and are virtually impossible to move again once they are installed.

Minimum Lot Size is the minimum area or size requirement for a parcel of land to be eligible for development or subdivision. Local authorities use this zoning regulation to control and manage land use, density, and the overall character of an area.

Mixed-use Zoning is a zoning approach that allows different land uses within a single area or development. It is designed to create vibrant, walkable communities by combining residential, commercial, and sometimes industrial or institutional uses in close proximity.

Multi-family Housing refers to residential buildings or developments that contain multiple housing units within a single structure. Multi-family housing can take various forms, including apartment buildings, townhouses, duplexes, triplexes, and larger complexes such as high-rise buildings or housing developments. Units in a multi-family development can be rented or sold in a condominium arrangement (see: Condominium).

N

New Urbanism is an urban planning and design movement that emerged in the 1980s as a response to the negative impacts of suburban sprawl and car-centric development. It advocates for the creation of walkable, mixed-use, and socially vibrant communities that prioritize human-scale design, connectivity, and sustainability.

NIMBY stands for “Not In My Backyard” and refers to the opposition to some undesired land use by people in the local area of the proposed site. In housing contexts, it usually refers to people who oppose new development, especially dense, mixed-use, and affordable development.

In zoning terms, Non-conforming denotes a land use, structure, or lot that lawfully existed before the current zoning ordinances were enacted or amended, but doesn’t comply with all of the current zoning regulations. For example, a commercial business operating in an area that gets rezoned for residential use would become a non-conforming use.

O

An Overlay District is an additional layer of zoning regulations that modifies the base zoning regulations for a particular area. Overlay districts are typically implemented to address specific issues or goals, like historic preservation or climate resiliency.

P

Performance-based Zoning, also known as impact-based or effects-based zoning, is a type of land use regulation that specifies the performance standards or environmental impacts that developments must meet. It is an alternative to traditional zoning, which prescribes exact uses for each parcel of land.

In other words, instead of focusing on what type of building or activity can occur on a piece of land (e.g., residential, commercial, industrial), performance-based zoning is concerned with the potential impacts or outcomes of the development (e.g., noise levels, traffic generated, environmental impacts, visual aesthetics).

Performance standards might address a variety of issues, such as:

• Noise pollution: A limit might be set on the acceptable decibel level a development produces.
• Air and water quality: Standards may be set on emissions or the treatment of waste.
• Traffic: Standards could regulate the amount of traffic that a development can generate.
• Visual impact: Standards might limit the height of buildings or require certain aesthetic features to preserve community character.

A Planning Commission, also known as a Planning Board or Planning Committee, is a local appointed or elected body that is charged with overseeing and making decisions related to land use, development, and growth in a community. The exact roles and responsibilities of a Planning Commission vary depending on the laws and regulations in a given jurisdiction. However, their goal is to guide development in a way that promotes the health, safety, and general welfare of the community, while balancing the rights and interests of property owners.

A Planned Residential Development (PRD), also known as a Planned Unit Development (PUD), is a type of development intended to maximize flexibility in zoning and design regulations to create integrated, mixed-use communities. PRDs typically involve clustering residences into more compact areas than standard zoning regulations permit. This helps to preserve open space and create community amenities, such as parks, community buildings, and walking trails.

PRDs can include a variety of housing types (single-family homes, townhouses, apartments, etc.) in one development. They may also include commercial, recreational, or other non-residential uses. PRDs are often designed with a holistic approach to land use planning, considering the layout of buildings, streets, and public spaces to create walkable, connected communities.

A Primary Dwelling is the housing unit where a person or family resides and typically spends the majority of their time.

Proffers are commitments made by a developer or property owner to provide certain public benefits or amenities to mitigate the impact of the development in exchange for approval of the development. The developer and the local government or planning authorities typically negotiate proffers during the entitlement process.

Q

R

Rezoning is the process of changing the zoning classification of a particular property or group of properties. It modifies the allowed uses, standards, or restrictions for the property as set out in the local zoning ordinance or land use code.A municipal or county governing body typically enacts this change.

A Right-of-Way (ROW) is a type of easement granted or reserved for transportation purposes, including: 

• highways
• pedestrian and cyclist paths
• rail transport
• canals
• electrical transmission lines
• oil and gas pipelines

This can also include considerations for trees, streetlights, or other aspects of the public realm.

In urban planning, managing and planning rights-of-way is an important task because they are crucial for transportation and the provision of utilities.

S

Single-family Attached denotes a type of housing where a small number of single-family homes—usually two—share common walls, but have their own entrances, utilities, driveways, yards, etc. Single-family attached homes are commonly called rowhouses, townhouses, or townhomes. However, townhouses are sometimes considered technically distinct (see: Townhouses).

Single-family Detached, often simply referred to as single-family, denotes a type of residential dwelling that stands alone and is not physically attached to or touching any other dwellings. It is a separate, self-contained structure designed to accommodate one household.

A Setback is the minimum required distance between a building or structure and the property line, street, or neighboring buildings. It is a zoning regulation that determines how close a building can be constructed to the edge of the property.

A Special Use Permit (SUP), also known as Conditional Use Permit or Special Exception, is a zoning exception that allows a property owner to use their land in a way not typically permitted within the zoning district, under specific conditions.

A Starter Home is the first home someone buys in their lifetime. Starter homes are usually small and inexpensive, with only two or three bedrooms. People buying starter homes are typically only just starting families, and prioritize affordability over space.

Subdivision is the process of dividing a larger tract of land into smaller, individual parcels or lots. It involves dividing the land into legally defined units that can be sold, developed, or transferred separately. The individual lots are collectively referred to as a subdivision as well. Subdivisions can range from small residential lots to large-scale developments with multiple residential, commercial, or industrial parcels.

T

Townhouses, also known as a townhomes, are a type of housing where dwelling units are arranged in rows and each unit has its own entrance and usually extends vertically over two or more floors. Townhomes are designed to provide a balance between the features of a single-family home and the convenience of multi-family housing. They are sometimes considered to be distinct from single-family attached homes or rowhouses (see: Single-family Attached), as townhouses can be constructed as multi-family buildings instead of individual homes that share walls. In such cases, the townhomes may be rented by a single owner or sold under a condominium arrangement (see: Condominium).

Transferable Development Rights (TDRs) are a land use policy tool that allows the rights to develop a parcel of land to be transferred from one property to another. This tool is often used to control and direct growth toward certain areas while protecting others. TDR programs can create “sending districts,” places with characteristics that the locality would like to preserve where landowners are allowed to sell their TDRs. The development rights are then sold to developers in “receiving districts” to allow denser development. Some cities allow TDRs to be sold to adjacent property owners, which has resulted in the recent boom in “supertall” skyscrapers in New York City.

Transit-Oriented Development (TOD) is an urban planning and development approach that focuses on creating compact, pedestrian-friendly, and mixed-use communities. These communities are centered around public transportation hubs, such as urban rapid transit, commuter transit, or intercity transit stations. 

The goals of TOD are to: 

• encourage and ease the use of public transportation
• reduce reliance on private vehicles
• promote sustainable and livable urban environments

A Triplex is a type of residential building that consists of three separate housing units or apartments, each usually occupying a separate floor or level of the structure.

U

V

A Variance is an officially approved deviation from the zoning ordinance, building code or municipal code. The variance relieves a property owner from certain zoning regulations when the strict enforcement of the regulations would cause undue hardship. For example, a business might request a variance to provide fewer parking spaces than are required by the code because it can demonstrate that its operations require fewer spaces.

W

X

Y

YIMBY stands for “Yes In My Backyard” and refers to supporters of new development, especially dense, mixed-use, and affordable housing. YIMBY is intended to directly oppose and counteract NIMBY in public discussions around housing and community development. It appears to have originated in a 1993 essay by Robert W. Lake in the Journal of the American Planning Association.

Z

A Zoning District, often shortened to “zone” or “district,” is a designated area within a municipality or jurisdiction that is subject to specific regulations and land use restrictions. Local governments create zoning districts to regulate and control the use of land, buildings, and structures within their jurisdiction.

Each zoning district is assigned a specific zoning classification or designation, which determines what is permissible, including: 

• land uses
• building types
• density
• height restrictions
• setbacks
• parking requirements
• other development standards

Reading List

Want to learn more about zoning and land use in the United States? We recommend these books and online resources: 

Zoning, Land Use, and the Reproduction of Urban Inequality (2022) 
Author: Michael C. Lens 

While sociologists study the consequences of zoning and other causes of unaffordable housing and segregation, they rarely examine zoning itself. This article argues for a sociological research agenda on zoning and land use.

Zoning and Segregation in Urban Economic History (2022) 
Authors: Allison Shertzer, Tate Twinam, Randall Walsh 

This essay explores the long-run impact of zoning on the development of cities.  It highlights the key gaps in understanding how urban and suburban zoning has contributed to segregation within cities and across metropolitan areas. The authors also discuss the importance of racial dimensions when studying land use regulations, even when the policies in question are ostensibly race neutral.

A History of Zoning in Three Acts (2017) 
Author: Spencer Gardner 

The first in a three-part series examining the history of zoning, its growth throughout the last century, and its implications for building strong towns today.

The Color of Law (2017) 
Author: Richard Rothstein 

This book discusses how segregation in America is the byproduct of explicit government policies at the local, state, and federal levels. The Color of Law was designated one of ten finalists on the National Book Awards’ long list for the best nonfiction book of 2017.

Zoning in 20th Century American Cities (2016)
Author: Christopher Silver

A brief summary of the history of 20th century zoning practices. 

Zoned in the USA: The Origins and Implications of American Land-Use Regulation (2014) 
Author: Sonia Hirt 

This book explores municipal zoning from a comparative and international perspective.  It draws on archival resources and contemporary land-use laws from several countries to challenge assumptions about American cities and the laws that guide them.

Urban Planning and the African American Community: In the Shadows (1997)
Authors: June Manning Thomas, Marsha Ritzdorf 

The book focuses on areas of zoning and real estate, planning and public policy, African American initiatives and responses to urban planning, and urban planning education. Individual chapters examine the racial origins of zoning in American cities.

Residential Segregation by Law, 1910-1917 (1968)
Author: Roger L. Rice

This essay discusses the context and cases related to legal racial segregation in the second decade of the 20th century.