Types

• Floor Area Ratio and Lot Coverage
  Zoning bulk controls that cap total floor area as a multiple of lot area and building footprint as a percentage of the lot.
• Height and Story Limits
  Zoning limits on building height and number of stories, how height is measured from grade to roof, and the common exceptions for roof structures.
• Landscape, Buffers, and Open Space
  Zoning requirements for landscaping, parking lot islands, buffers and screening between uses, and required open space on a lot.
• Overlay Districts and Historic Review
  How overlay districts add rules over base zoning for historic, floodplain, airport, and design areas, and how certificates of appropriateness work.
• Parking and Loading Requirements
  Zoning requirements for off-street parking and loading, including how minimums are set, current reform trends, and typical loading space sizes.
• Permitted, Conditional, and Accessory Uses
  How zoning sorts uses into permitted by right, conditional or special, and accessory categories, and what each category means for approval and design.
• Setbacks, Yards, and Build-To Lines
  Zoning rules for required distances between buildings and lot lines, the front, side, and rear yards, and build-to lines at the street.
• Site Plan Review and Entitlements
  The local approval path for development, covering pre-application meetings, site plan review, rezoning, conditional use, variances, and the handoff to building permits.
• Variances, Appeals, and Nonconforming Conditions
  How zoning allows relief from its rules through variances and appeals, and how lawful existing buildings and uses become nonconforming and are protected or lost.
• Zoning Districts and Use Regulations
  How zoning divides a city into residential, commercial, industrial, and mixed-use districts, and how to read a district's use table and dimensional standards.

Scope and application

• Regulates how land is used and how buildings sit on it: permitted activities, density, building height, lot coverage, setbacks, landscaped versus paved space, and required parking
• Applies parcel by parcel through a zoning map that assigns each lot to a district; a project must satisfy the ordinance before a building permit is issued
• Separate from the building code. The building code governs how a building is built and made safe; zoning governs whether and where it may be built. A project must satisfy both, and the stricter limit governs where they overlap
• Local covenants, deed restrictions, and subdivision or design guidelines add further limits that are not part of the ordinance
• State and federal rules can override or shape local zoning, for example for accessory dwellings, group homes, or parking minimums
• Zoning rules for a specific site are never generalized here; the notes give typical structure, with illustrative numbers marked as examples

Legal basis and administration

• Zoning is an exercise of local police power under state enabling laws. The US Supreme Court upheld zoning in Village of Euclid v. Ambler Realty Co. (1926), and use-separating districts are often called Euclidean zoning
• Euclidean zoning is by far the most prevalent type in the US; performance, incentive, and form-based zoning are other approaches
• A planning commission usually advises on amendments and many approvals; a legislative body such as a city council adopts and amends the ordinance and map; a board of zoning appeals or board of adjustment decides variances and appeals of staff decisions
• Amendments (rezonings) are reviewed in court for whether they are arbitrary or reasonably related to police power, and owners have no vested right to keep a district unchanged
• Most systems have a variance procedure for hardship cases; unwarranted variances risk spot zoning claims, which most state laws prohibit
• Zoning changes over time, so a lawful existing use or building may become nonconforming

How an ordinance is structured

• District codes are not standardized. Codes often begin with R, C, or I, but the same code can mean different things in different cities (an R5 district may be multifamily housing, five units per acre, or 5,000 sq ft lots)

Using the notes

The usual order of a zoning check on a site:

1. Find the parcel's district and any overlays on the zoning map, then read Zoning Districts and Use Regulations and Overlay Districts and Historic Review
2. Confirm the use is allowed by right, needs approval, or is an accessory use, under Permitted, Conditional, and Accessory Uses
3. Compute the buildable envelope from Setbacks, Yards, and Build-To Lines, Height and Story Limits, and Floor Area Ratio and Lot Coverage
4. Check site requirements under Parking and Loading Requirements and Landscape, Buffers, and Open Space
5. If the design does not fit, look at the relief routes in Variances, Appeals, and Nonconforming Conditions
6. Plan the approval path and schedule under Site Plan Review and Entitlements

Where to find the local rules

Sources

• Wikipedia: Zoning in the United States, https://en.wikipedia.org/wiki/Zoning_in_the_United_States
• Wikipedia: Variance (land use), https://en.wikipedia.org/wiki/Variance_(land_use)
• Wikipedia: Setback (land use), https://en.wikipedia.org/wiki/Setback_(land_use)