Growth Management Act. The Growth Management Act (GMA) is the comprehensive land use planning framework for counties and cities in Washington. The GMA establishes land-use designation and environmental protection requirements for all Washington counties and cities. The GMA also establishes a significantly wider array of planning duties for 28 counties, and the cities within those counties, that are obligated to satisfy all planning requirements of the GMA. These jurisdictions are sometimes said to be fully planning under the GMA.
 
Counties that fully plan under the GMA must designate urban growth areas (UGAs), within which urban growth must be encouraged and outside of which growth may occur only if it is not urban in nature. Each city in a county must be included in a UGA. Planning jurisdictions must include within their UGAs sufficient areas and densities to accommodate projected urban growth for the succeeding 20-year period.
 
The GMA also directs fully planning jurisdictions to adopt internally consistent comprehensive land use plans. Comprehensive plans are implemented through locally adopted development regulations, and both the plans and the local regulations are subject to review and revision requirements prescribed in the GMA. Comprehensive plans must be reviewed and, if necessary, revised every ten years to ensure that it complies with the GMA. When developing their comprehensive plans, counties and cities must consider various goals set forth in statute.
 
Each comprehensive plan must include a plan, scheme, or design for certain enumerated elements, including a mandatory housing element. The housing element must ensure the vitality and character of established residential neighborhoods and among other requirements consider the role of accessory dwelling units in meeting housing needs.
 
Accessory Dwelling Units. Any county fully planning under the GMA, city with a population over 20,000, or county with a population over 125,000 must have accessory dwelling unit (ADU) provisions incorporated in their development regulations, zoning regulations, or official controls. These provisions must be consistent with a 1993 report from the Department of Community, Trade, and Economic Development that provided recommendations to encourage the development and placement of ADUs in areas zoned for single-family residential use. However, local communities have some flexibility to adapt these recommendations to local needs and preferences.

As of July 1, 2021, fully planning cities under the GMA may not require the provision of off-street parking for ADUs within a quarter mile of a major transit stop, such as a high capacity transportation system stop, a rail stop, or certain bus stops, unless the city determines that on-street parking is infeasible for the ADU.
 
An ADU is a residential living unit providing independent living facilities and permanent provisions for sleeping, cooking, sanitation, and living on the same lot as a single-family home, duplex, triplex, townhome, or other housing unit. A short-term rental is a lodging use, outside of a hotel, motel, or bed and breakfast, in which a room is offered for a fee for fewer than 30 consecutive nights.

Accessory Dwelling Units—General Requirements. A city or county fully planning under the GMA must adopt or amend by ordinance, and incorporate into their development regulations, zoning regulations, and other official controls at least three of the following policies to take effect six months after the jurisdiction's next periodic comprehensive plan update:

• the city or county may not establish a requirement for the provision of off-street parking for ADUs;
• the city or county may not assess impact fees on the construction of ADUs greater than 50 percent of the impact fees that would be imposed on the principal unit;
• the city or county may not require the owner of a lot on which there is an ADU to reside in or occupy the ADU or another housing unit on the same lot; and
• the city or county must allow at least two ADUs on all lots located in all zoning districts within an UGA that allow for single-family homes in the following configurations:
  1. one attached ADU and one detached ADU;
  2. two attached ADUs; or
  3. two detached ADUs, which may be comprised of either one or two detached structures.

 
In addition to the above policies, a city or county must comply with all of the following policies:

• permit ADUs in structures detached from the principal unit;
• allow an ADU on any lot that meets the minimum lot size required for the principal unit;
• may not establish a maximum gross floor area requirement for ADUs less than 1000 square feet;
• may not establish roof height limits on ADUs less than 24 feet, unless the height limitation that applies to the principal unit is less than 24 feet, in which case the jurisdiction may not impose roof height limitation on ADUs less than the height limitation that applies to the principal unit;
• may not impose setback requirements, yard coverage limits, tree retention mandates, restrictions on entry door locations, aesthetic requirements, or requirements for design review for ADUs that are more restrictive than those for principal units;
• must allow ADUs to be sited at a lot line if the lot line abuts a public alley, unless the jurisdiction routinely plows snow on the public alley;
• must allow ADUs to be converted from existing structures, including but not limited to detached garages, even if they violate current code requirements for setbacks or lot coverage;
• may not prohibit the sale or other conveyance of a condominium unit independently of a principal unit solely on the grounds that the condominium unit was originally built as an ADU; and
• may not require public street improvements as a condition of permitting ADUs.

 
Incentives. A city or county may adopt ordinances, development regulations, and other official controls that waive or defer fees, including impact fees, defer the payment of taxes, or waive specific regulations. A city or county may only offer such reduced or deferred fees, deferred taxes, waivers, or other incentives for the development or construction of ADUs if:

• the units are located within a UGA; and
• the units are subject to a program adopted by the city or county with effective binding commitments or covenants that the units will be primarily utilized for long-term housing.

 
Accessory Dwelling Units Guidance Recommendations.  The Department of Commerce (Commerce) must revise its recommendations for encouraging ADUs to include the provisions in this act no later than December 31, 2023. During each comprehensive plan review, Commerce must review local government comprehensive plans and development regulations for compliance with this act and the recommendations provided by Commerce.
 
Applicability of Provisions. A fully planning city or county must adopt or amend by ordinance, and incorporate into their development regulations, zoning regulations, and other official controls the ADU requirements established by this act to take effect six months after the jurisdiction's next periodic comprehensive plan update. Any conflicting development regulations are preempted and superseded after this deadline.
 
Nothing in this act requires or authorizes a city or county to authorize the construction of an ADU in a location where development is restricted under other laws, rules, or ordinances as a result of physical proximity to on-site sewage system infrastructure, critical areas, or other unsuitable physical characteristics of a property.
 
Nothing in this act prohibits a city or county from:

• restricting the use of ADUs for short-term rentals;
• applying public health, safety, building code, and environmental permitting requirements to an ADU that would be applicable to the principal unit, including regulations to protect ground and surface waters from on-site wastewater;
• applying generally applicable development regulations to the construction of an ADU, except when the application of such regulations would be contrary to the ADU policies established by this act;
• prohibiting the construction of ADUs on lots not connected to or served by public sewers; or
• prohibiting or restricting the construction of ADUs in residential zones with a density of one dwelling unit per acre or less that are within areas designated as wetlands, fish and wildlife habitats, flood plains, or geologically hazardous areas.

 
The ordinances, development regulations, and other official controls adopted or amended in accordance with these requirements must only apply to the portions of towns, cities, and counties within UGAs. Attached or detached ADUs may not be considered as contributing to the overall underlying density within the UGA boundary of a county.
 
Liability. A restrictive covenant or deed restriction created after the effective date of the act may not prohibit the construction, development, or use of an ADU within a UGA. A city or county that issues a permit for the construction of an ADU may not be held civilly liable on the basis that the construction would violate the restrictive covenant or deed restriction created after the effective date of the act.
 
Any action taken by a city or county to comply with the above policies is not subject to legal challenge under the Growth Management Hearings Board or the State Environmental Policy Act.
 
Accessory Dwelling Units—Definitions. Terms, including gross floor area and principal unit are defined.
 
Statutes Repealed. Statutes pertaining to accessory apartments are repealed.