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 mandatory elements, including a housing element.  The housing element must ensure the vitality and character of established residential neighborhoods.

Co-living housing is a residential development with sleeping units that are independently rented and lockable and provide living and sleeping space, and residents share kitchen facilities with other sleeping units in the building.  Local governments may use other names to refer to co-living housing including congregate living facilities, single room occupancy, rooming house, boarding house, lodging house, and residential suites. 

Within six months of its next comprehensive plan update, a fully planning city or county must adopt development regulations allowing co-living housing in any zone within a UGA that allows multifamily residential uses, including mixed-use development.  In addition, a city or county may not require co-living housing to:

• contain room dimensional standards larger than that required by the State Building Code, including dwelling unit size, sleeping unit size, room area, and habitable space;
• provide a mix of unit sizes or number of bedrooms; 
• include other uses; 
• provide off-street parking within one-half mile walking distance of a major transit stop;
• provide more than 0.25 off-street parking spaces per sleeping unit; or 
• meet any standards that are more restrictive than those that are required for other types of residential uses in the same zone. 

A city or county may only require a review, notice, or public meeting for co-living housing that is required for other types of residential uses in the same location, unless otherwise required by state law.  A city or county may not treat a sleeping unit in co-living housing as more than one-quarter of a dwelling unit for purposes of calculating dwelling unit density or fees for permitting and utility connections and may not exclude co-living housing from participating in affordable housing incentive programs.