Seattle, WA, Municipal Code

Updated July 2023

By: Seattle City Planning
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Table of Contents

Accessory Dwelling Units

The city’s land use code permits internal, attached, and detached accessory dwelling units (ADUs) by right in single-family residential districts, subject to use-specific standards (§23.44.041). These standards address units per lot, owner occupancy, total occupancy, unit size, entrances, parking, lot size and dimensions, lot coverage, setbacks, height, separation between structures, conversion of accessory structures, and removal.

Affordable Housing Programs

The city’s codified ordinances contain several affordable housing policies. §23.54.015 lists parking requirements for residential uses in Table B, showing that multifamily dwelling units that are rent and income-restricted at or below 80 percent of the median income have no minimum requirement. Chapter 23.58B discusses the affordable housing impact mitigation program for commercial development, which holds commercial permit applicants accountable for mitigating the impact on the need for affordable housing through a payment or performance option. Chapter 23.58C lays out the city’s mandatory housing affordability for residential development, including the payment and performance options.

Biophilic Planning

This city’s municipal code addresses biophilia by creating a Green Factor measurement and having green street regulations. The Green Factor measurement is a model that promotes green stormwater infrastructure by improving the quality of landscaping in new developments, including multifamily residential buildings (§23.86.019). Biophilic elements such as green roofs and tree preservation score high on the Green Factor measurement. The Green Street regulations create a high-quality open space by having trees and landscaping while also being pedestrian orientated. The downtown Green Street improvements offer funding incentives by providing developers who constructed a green street with an increased floor-area-ratio.

Creative Placemaking

The city’s land use code establishes the Pike/Pine Overlay District, which encourages locating arts and culture facilities within the designated area. It includes exceptions to floor area limits for uses that support the area’s arts district character, such as building space used for theater or arts facilities, performing arts spaces, and artist-studio dwellings from floor area calculations (§23.73.010). Additionally, it gives flexibility related to building height restrictions for uses that promote the development objectives of the district, including theater space or arts facilities (§23,73.014).

Design Review

The city's land use code addresses design review (Chapter 23.41). Tables lists thresholds (size or number of residential units) for design review in different zoning districts as well as in the downtown zones. Optional full and administrative design review is available to certain other developments. The city is divided into seven design review districts, each with its own design review board; the code lists administrative requirements for boards including composition and meeting requirements (§23.41.008). Design review guidelines for each neighborhood are incorporated by reference (§23.41.010). The code lays out requirements for the design review process (§23.41.014), administrative design review (§23.41.016), a streamlined design review process (§23.41.018), and a master-planned community design review process (§23.41.020).

Environmentally Sensitive Areas

The city’s environmental protection and historic preservation code aims to protect critical areas through development regulations that avoid and mitigate adverse environmental impacts. It includes standards for general development, mitigation, tree and vegetation and impervious surface management, and pesticide, herbicide, and fertilizer use (§25.09.060 et seq.). Additionally, it lists geologic hazard areas, steep slope erosion hazard areas, flood-prone areas, wetlands, fish and wildlife habitat conservation areas, and abandoned landfills as environmentally critical areas (§25.09.012) and establishes site specific regulations (§25.09.080 et seq.).

Food Systems | food trucks

The city’s street and sidewalks use code offers detailed information and diagrams related to mobile food vending (§15.17). The regulations require permitting through the Department of Transportation (§15.17.005) and outline standards for mobile vending in the stadium area (§15.17.050), on public sidewalks and in plazas (§15.17.100), from a curb space (§15.17.120), and from a public place ($15.70.130) These standards include curb setbacks, providing for safe pedestrian passage including ADA compliance, maintaining public place conditions (§15.17.152)and distance requirements from brick-and-mortar business and parks.

Green Building

The city’s municipal code highlights a green building standard. It states that buildings must comply with the green building standard (§23.58D.002).

Green Stormwater Infrastructure

The city’s municipal code presents street and land-use design requirements to allow for green stormwater infrastructure. It supports the design of curb setbacks for green stormwater infrastructure (§15.06.050), presents a requirement option for “planned community developments” (§23.49.036), and allows green infrastructure in restricted setbacks for properties in both commercial districts (§23.47A.014.G.9) and master planned communities (§23.75.140.J.9). The municipal code also outlines the principles of “planned residential development” including promoting green stormwater infrastructure and mitigating impact in environmentally sensitive areas (§23.44.034).

The city's land use code includes a Green Factor measurement, a model that promotes green stormwater infrastructure by improving the quality of landscaping in new developments, including multifamily residential buildings (§23.86.019). And it includes Green Street regulations, which create a high-quality open space by having trees and landscaping while also being pedestrian orientated. The downtown Green Street improvements offer funding incentives by providing developers who constructed a green street with an increased floor-area-ratio.

Historic Preservation

The city’s codified ordinances establish a landmarks preservation board, designation and design review processes, and specific regulations for seven landmark districts (Chapters 25.12 to 25.30). A table of historic landmarks is included in Chapter 25.32.

Home Occupations

The city’s land use code permits home occupations by right, subject to use-specific standards (§23.42.050). Home occupations must comply with location and space, delivery, customer, parking, dwelling modification, storage, sign, employee, and nuisance standards (§23.42.050).

The ordinance includes home-based daycare standards (§§23.42.050.D, F.1, H, & L).

Marijuana-Related Uses

The city’s land use code permits multiple types of marijuana-related uses by right, subject to use-specific standards (§23.42.058). It defines “marijuana activity, major” to include nonresidential production, processing, and selling of marijuana and marijuana-infused products (§23.84A.025).

Its use-specific standards for major marijuana activities address zoning district use-permissions; state licensure; separation from schools, playgrounds, childcare centers, arcades, libraries, public parks, transit centers, recreation facilities, and other marijuana-related uses.

The city’s business licensing code includes additional application and operational requirements for marijuana processors, producers, and retailers (§6.500).

Rethinking Off-Street Parking Requirements

The city’s land use code includes multiple types of policy-driven off-street parking requirements. It exempts most uses in downtown districts from minimum off-street parking requirements (§23.40.019). It establishes maximum parking requirements for select uses in specific districts (§23.54.015.C). And it authorizes parking reductions for landmark structures, shared parking facilities, transit proximity, cooperative parking, and car share programs (§23.54.020).

Scenic View Protection

The city’s municipal code protects both public and private scenic views. The land use code protects view corridors in shoreline area by providing standards to protect view corridors in shoreline environments, such as limitations on allowed structures and parking placement(§23.60A.170). The environmental policies and procedures protect public view to both natural and human-made features, including mountains and skylines, from designated public spaces. Public view mitigation measures include changing the height, bulk, profile, or location (§25.05.675P).

Shared Mobility

The city’s codified ordinances contain regulations that address and encourage carsharing and ridesharing services within the jurisdiction.

Its traffic code establishes a free-floating carsharing parking program to encourage a mode shift from private vehicle ownership (§11.23.160) and presents the annual fees for carsharing parking permits (§11.23.150). It also requires parking permits for ridesharing vehicles (§11.23.390), allows free parking for ridesharing parking permit holders (§11.23.410), and addresses the unlawful use of ridesharing permits (§11.23.415).

The land-use code requires that major institutions have designated parking spaces for ridesharing vehicles (§23.54.016-D-1). It also authorizes the director to reduce required parking spaces for new or existing office and manufacturing uses by one and nine-tenths (1.9) spaces for every carpool space and by six (6) spaces for every vanpool space (§23.54.020-F-3).

Social Equity

The city’s codified ordinances include a Fair Chance Housing Ordinance. Chapter 14.09 prohibits the use of a tenant’s criminal history in housing decisions and outlines an investigation and enforcement process.

Tiny Houses and Micro-Apartments

The city’s land use code defines and regulates micro-apartments as a distinct type of dwelling. It defines a “small efficiency dwelling unit” as any efficiency unit with less than 220 ft2 of living space (§23.84A.008.D & §1208.4). Standards for small efficiency dwelling units address habitable and gross floor area, food preparation areas, bathroom facilities, and parking (§23.42.048.B, §23.54.015 & Small Efficiency Dwelling Units).

Tree Preservation and the Urban Forest

The city's environmental protection regulations establish protections for existing trees on undeveloped and developed lots (§25.11). On undeveloped lots, all trees over 6 inches in diameter are protected. On developed lots, protections cover "exceptional" trees, which are mature trees with special historical, ecological, or aesthetic value. Provisions address purpose and intent, definitions, exemptions, restrictions on tree removal, exceptional tree determination and tree protection area delineation in different zones, tree protection on development sites in neighborhood residential zones, tree protection on development sites in low-rise zones, tree protection on development sites in mid-rise and commercial zones, tree replacement and site restoration, tree service provider registration, and enforcement and penalties.

Food Systems | Urban Livestock

The city's land use regulations permits outright the keeping of small animals, farm animals, domestic fowl, and bees in all zones as an accessory use to any principal use or permitted conditional use, subject to standards (§13.42.052).

Up to 4 small animals, including pygmy goats, are permitted in single-family zones on lots of at least 20,000 SF, with 1 additional small animal permitted for each additional 5,000 SF of lot area. One potbellied pig is permitted. Up to 8 domestic fowl may also be kept on any lot, with roosters prohibited; additional fowl are permitted on lots greater than 10,000 SF with community gardens or urban farms. Cows, horses, sheep, and other farm animals except swine are permitted on lots of at least 20,000 SF, with 1 animal permitted per 10,000 SF. Setbacks are established for the keeping of each animal type.

Beekeeping is permitted as an accessory use if registered with the state department of agriculture; up to 4 hives are permitted on lots less than 10,000 SF, and standards address setbacks, location, and screening.

A city website summarizes the city's animal codes.

Seattle, WA

2010 Population: 608,660

2010 Population Density: 7,250.87/square mile