Zoning Systems and Codes

Types of Zoning Introduction Zoning is a land-use regulation tool that municipalities use to control how land can be developed. There are several major approaches to zoning, each with different goals and mechanisms. Understanding these types is essential because they shape urban development, housing availability, environmental protection, and community character. The most common approach in the United States is use-based zoning, but alternative approaches like form-based zoning and performance zoning are becoming increasingly popular as cities seek more flexible, innovative solutions. Use-Based Zoning: The Foundation Use-based zoning divides land into districts based on the type of activity permitted—whether residential, commercial, industrial, or mixed. This is by far the most dominant zoning approach in the United States. The fundamental principle is straightforward: different uses are grouped together in designated areas, and regulations specify what activities are allowed in each district. Within use-based zoning, there are two main subtypes: Single-Use (Euclidean) Zoning Single-use zoning designates each district for one specific use only. For example, a residential zone allows only houses and apartments, a commercial zone allows only shops and offices, and an industrial zone allows only factories and warehouses. There is no mixing of uses. This approach is also called Euclidean zoning because it originated from the landmark 1926 Supreme Court case Village of Euclid v. Ambler Realty. In this case, the Court ruled that a village could legally restrict land use through zoning ordinances. The case established the constitutional validity of zoning as we know it, making single-use zoning the standard approach for the next century. The image above shows a typical single-use zoning map with different colors representing residential, commercial, and other distinct zones. Why single-use zoning? The original motivation was to prevent incompatible uses from conflicting. Keeping noisy factories away from homes protects residents and property values. However, as you'll see later, this approach has significant drawbacks. Mixed-Use Zoning Mixed-use zoning permits different types of activities—residential, commercial, office, and public uses—to coexist in the same area. This can happen in two ways: Vertical mixing: Different uses are stacked in the same building, such as apartments on upper floors with shops on the ground floor. Horizontal mixing: Different uses occupy adjacent buildings in the same neighborhood. Mixed-use development encourages walkability and vibrant neighborhoods where people can live, work, and shop in the same area. However, it requires careful design to ensure incompatible uses don't negatively affect each other. Form-Based Zoning While use-based zoning focuses on what activities are allowed, form-based zoning focuses on how buildings and streets should look and function. Instead of separating uses, form-based codes regulate the physical characteristics of development: building height, setbacks (distance from the street), lot size, street width, and architectural standards. Form-based codes include four key components: Regulating plan: A map showing different zones or areas Public standards: Requirements for public spaces like streets and sidewalks Building standards: Requirements for private buildings (height, setback, façade type) Precise technical definitions: Clear, specific language to avoid ambiguity The advantage of form-based zoning is flexibility: it can allow mixed uses while still controlling the urban form. A building might be residential or commercial, but it must meet the same height and setback requirements. This approach is increasingly popular in urban revitalization and transit-oriented development. Performance Zoning Performance zoning sets goal-oriented criteria that developments must meet, rather than prescribing specific uses or forms. Instead of saying "this is a residential zone," performance zoning might say "any project must achieve a walkability score of at least 70" or "include at least 15% affordable housing units." This approach often uses a points or credit system where developers earn points by meeting various environmental, social, or design goals. For example: Preserving wetlands might earn 10 points Providing affordable housing might earn 5 points Including public transit access might earn 7 points Performance zoning can be combined with use-based districts, creating a hybrid approach. The advantage is flexibility—developers can achieve the goals however they choose, promoting innovation. The disadvantage is that implementation requires more expertise and case-by-case evaluation. Incentive Zoning Incentive zoning (also called bonuses) rewards developers for providing public benefits by allowing greater density or height. For example, a developer might normally be permitted to build a 10-story building, but could build 12 stories if they include affordable housing units or create a public plaza. Common incentives include: Open space and plazas: Developers get higher density in exchange for creating public gathering spaces Affordable housing: Reduced parking requirements or floor area ratio (FAR) bonuses for including affordable units Walkability: Permission for ground-floor retail and narrower streets in exchange for more residential units The logic is straightforward: cities give developers something valuable (increased profit potential) in exchange for public goods. This approach works well when there is market demand for additional density, but may be ineffective in weaker real estate markets. The Evolution: Hierarchical vs. Flat Single-Use Zoning Understanding the difference between hierarchical and flat single-use zoning is important for understanding how zoning evolved in America. Hierarchical Zoning (Early Approach) In hierarchical zoning, districts are arranged in a pyramid with different levels of restrictiveness. A typical hierarchy is: Residential (most restrictive): Only houses and apartments allowed Commercial (less restrictive): Commercial buildings allowed, plus residential buildings may be permitted Industrial (least restrictive): Industrial uses allowed, plus commercial and residential uses may be permitted This structure allows "downward compatibility"—a use can flow downward in the hierarchy, but not upward. A house cannot be built in a commercial zone, but a store can be built in a residential zone. Flat Zoning (Modern Standard) By the mid-twentieth century, flat zoning became dominant. In flat zoning, each district is separate with no hierarchy. A residential zone allows only residential uses, a commercial zone allows only commercial uses, and an industrial zone allows only industrial uses. There is no "downward compatibility." Most U.S. municipalities today use flat single-use zoning as their primary approach, though many retain some hierarchical elements in their codes. The map above shows a flat single-use zoning structure with distinct, non-overlapping districts in different colors. Additional Zoning Tools and Strategies Beyond the main zoning types, municipalities use various specialized tools to address specific goals. Cluster Zoning Cluster zoning (also called open space zoning) groups residential units together more densely than typical zoning would allow, while preserving larger blocks of open space for recreation, conservation, or future development. For example, instead of spreading 50 homes across 50 individual lots across 50 acres, cluster zoning might permit those 50 homes on 20 acres, leaving 30 acres as open space. This approach: Preserves farmland and natural areas Reduces infrastructure costs (fewer miles of roads and utilities) Maintains rural character while accommodating growth Often requires negotiation between developers and local governments Planned Unit Development (PUD) A Planned Unit Development (PUD) is a single development that groups multiple compatible uses together—residential, commercial, office, and public spaces. Rather than following standard zoning district regulations, a PUD is negotiated directly between the developer and the local government. PUDs are common in: Mixed-use neighborhoods Large suburban developments Urban infill projects The advantage is flexibility and comprehensive planning of interconnected uses. The disadvantage is that negotiations are time-consuming and outcomes can be unpredictable. Overlay Zoning Overlay zones sit on top of existing base zones to address specific concerns without replacing the underlying zoning. An overlay zone adds requirements to parcels within it while the base zone remains in effect. Common uses for overlay zones include: Historic districts: Protecting architecturally significant buildings Wetlands: Protecting environmentally sensitive areas Transit-oriented development: Encouraging mixed-use, walkable development around transit stations Flood plains: Managing stormwater and reducing flood risk A property might be in a residential base zone AND a historic overlay district, in which case both sets of regulations apply. Inclusionary Zoning Inclusionary zoning requires or incentivizes developers to include a percentage of affordable housing units in new residential projects. For example, a new apartment building might need to include 15% of units rented at below-market rates to low- and middle-income households. Approaches include: Mandatory: Developers must include affordable units or pay into an affordable housing fund Voluntary with incentives: Developers get density bonuses or reduced parking requirements for including affordable units Inclusionary zoning addresses housing affordability but can increase development costs, potentially reducing overall housing supply. Many jurisdictions combine it with other affordable housing tools. Transferable Development Rights (TDR) Transferable Development Rights (TDR) allow property owners to separate development rights from land ownership. An owner in a "sending area" (where development is discouraged, such as farmland or historic districts) can sell their unused development capacity to an owner in a "receiving area" (where development is encouraged, such as downtown). This mechanism: Compensates property owners who accept development restrictions Concentrates growth in desired locations Preserves farmland, open space, or historic areas Requires careful market design to work effectively Spot Zoning Spot zoning rezones a small parcel in a way that is inconsistent with the surrounding area's zoning and the broader zoning plan. For example, rezoning a single house lot to commercial use when all surrounding lots are zoned residential would be spot zoning. Spot zoning is generally prohibited because it: Violates the comprehensive planning principle (zoning should follow an overall plan) Creates unpredictable neighborhoods May benefit one property owner unfairly Is vulnerable to legal challenges Understanding spot zoning is important because it represents what zoning regulations should not do. <extrainfo> Conditional Zoning Conditional zoning adds site-specific conditions to the zoning ordinance at the request of the property owner. The property owner might promise to meet certain conditions in exchange for receiving desired zoning. This can resemble spot zoning because it applies special rules to one property, and it may be challenged on similar grounds. Contract Zoning Contract zoning is a bilateral agreement in which a developer agrees to certain commitments (such as building public space or including affordable housing) in exchange for zoning changes. Like conditional zoning, it creates special rules for specific properties. Courts sometimes rule contract zoning illegal because it resembles a private contract rather than a general regulation. Fiscal Zoning Fiscal zoning uses zoning to attract high-tax-revenue uses (such as office parks or upscale retail) while discouraging uses that demand costly public services (such as multifamily housing or services for low-income residents). This zoning approach can exacerbate economic inequality across municipalities. Smart Zoning Smart zoning incorporates information and communication technologies to measure metrics like walkability and enable more flexible zoning decisions. For example, instead of fixed setback requirements, a smart zoning code might calculate setbacks based on street width, pedestrian movement patterns, and traffic data. Pattern Zoning Pattern zoning provides pre-approved building designs with expedited permitting processes. Developers can choose from approved designs and receive faster permits, reducing uncertainty and increasing housing supply. </extrainfo> Hybrid and Composite Zoning Real-world zoning is often a blend of approaches: Hybrid zoning combines two or more zoning types. For example, a downtown area might use form-based zoning to regulate building form while allowing mixed uses, combined with performance standards for environmental impact. Composite zoning integrates use, form, and site-design components to create flexible transition zones. This approach is useful for neighborhoods that need to evolve from one character to another, or for areas where different uses need to coexist thoughtfully. Summary Zoning types can be organized by their primary focus: Use-based zoning controls what activities are allowed (single-use or mixed-use) Form-based zoning controls how buildings look and function (height, setback, design) Performance zoning sets goal-oriented criteria that projects must meet Incentive zoning rewards developers for providing public benefits Additionally, municipalities deploy specialized tools like cluster zoning, PUDs, overlay zones, inclusionary zoning, and transferable development rights to address specific challenges. Understanding these tools is essential for understanding how zoning shapes cities, manages growth, and addresses goals like housing affordability, environmental protection, and community character.