UPDATE: HB 1337 was heard in the Local Government committee on January 12. If you support the bill, you can contact the members of the committee and ask them to pass it:

[email protected] (Chair) 206-307-0409
[email protected] (Vice Chair) 425-318-1303
[email protected] 509-665-0386
[email protected] 360-786-7966
[email protected] 425-939-8423
[email protected] 360-786-7866
[email protected] 425-279-5345

A shortage of homes is sending rents and prices skyward in communities all across Washington state. The squeeze is especially acute in urban neighborhoods where zoning laws allow only the most exclusive kind of home: a detached house on a big plot of land. One low-risk corrective action state legislators can take is to lift unnecessary local restrictions on backyard homes and mother-in-law apartments (a.k.a. accessory dwelling units, or ADUs).

Boosting ADUs does two good things: it increases the number of homes available, and those additional homes are more affordable than a typical stand-alone house. 

Boosting ADUs does two good things: it increases the number of homes available, and those additional homes are more affordable than a typical stand-alone house. #WAleg


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The problem is too many cities impose too many restrictive ADU rules, so far too few backyard homes and basement apartments get built. It’s no mystery which rule reforms work. Policy wonks identified the barriers to ADUs long ago, and on-the-ground evidence for removal of those barriers is piling up in Vancouver, BC, Portland, Seattle, and cities throughout California 

Over the past three years, Washington lawmakers committed to affordability solutions have sponsored several bills to end city laws that stymie ADU construction. But so far, only one narrow bill has passed, one that removes mandates for on-site parking for ADUs within a quarter-mile of transit—a tiny fraction of house lots in the state. 

Representative Mia Gregerson (D) has championed three ADU bills that spell out the proven reforms (see 20192020, and 2021). Support is broad-based but political opposition remains. This year, AARP published ADU policy recommendations that almost exactly mirror the Gregerson bills.  

Reforming ADU rules to allow more backyard homes won’t solve the state’s crippling shortage of housing all by itself! No single intervention will. But every extra home matters—and cottages and basements are naturally-affordable additions to our neighborhoods. In a housing crisis, you pursue every reasonable solution. And ADUs are the lowest hanging fruit there is. 

Delayed ADU reform has already denied homes to thousands of Washington families

How many ADU homes have been sacrificed during Washington’s delay in passing reforms for three years and counting? To give an idea of the potential, in the years after California passed statewide ADU reform in 2017, permits for ADUs exploded, comprising a whopping one fifth of all building permits issued in Los Angeles in 2019. 

From 2018 to 2019 ADU permits in California spiked by nearly 10,000. For a back-of-the-envelope estimate, scaling that down by the relative population of Washington yields about 1,900 more ADUs per year, which adds up 5,700 homes over three years. Delaying statewide ADU reform serves no purpose other than to exacerbate housing insecurity for thousands more Washington families. 

Washington’s next ADU bill: back to the future (again) 

In the 2022 legislative session, Representative Gregerson is back again with a strong bill—HB 1337—to set state standards to allow more ADUs in Washington communities. Here are the key provisions it will include, in order of decreasing importance: 

  • Lift bans on renters living on lots with ADUs 
  • Lift mandates to provide on-site parking    
  • Waive impact feeson ADUs 
  • Legalize detached ADUs (backyard homes or cottages) 
  • Legalize two ADUs per lot 
  • Allow ADUs on any lot that meets the minimum lot size for a detached house 
  • Allow ADU floor area of at least 1,200 square feet  
  • Do not allow ADU design standards that are more restrictive than those that apply to houses, including height, setbacks, yard coverage, tree retention, door locations, and aesthetics
  • Allow ADUs to be sited at the lot line when abutting a public alley 
  • Allow ADUs to be converted from existing structures (for example, detached garages) 
  • Allow the separate sale of an ADU as a condominium  

Seattle and Tacoma have passed strong reforms covering most of the above list, and a few other Washington cities have made good progress chipping away at it. But most cities retain far too many barriers that quash ADUs 

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  • The poster child Bellevue. Among Washington’s large cities, Bellevue’s typical home value of $1.3 million is the highest, while its rules for ADUs are the worst. One particularly egregious restriction: ADUs separate from the main house—that is, backyard cottages—-are flat-out illegal in Bellevue. 

    Delaying statewide ADU reform serves no purpose other than to exacerbate housing insecurity for thousands more Washington families. #WAleg


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    Also this session, Representative Sharon Shewmake has introduced a focused ADU bill—HB 1660—to do one simple but important reform to end anti-renter discrimination in local ADU rules (also included in Representative Gregerson’s bill). It would lift local bans on renters living in some of the homes on properties with ADUs, renter bans otherwise known as owner occupancy requirements (this article gives a rundown on why these rules are bad policy).  

    The reasons for opposing ADU reform are empty excuses 

    If their past actions are any indication, many city leaders and their lobbyists will oppose any bill that mandates the reform of local ADU laws, arguing that such decisions belong under local control. But here’s the elephant in the room they ignore: local control of zoning has given us the housing crisis! 

    Under status quo restrictive zoning enacted and preserved through local control, rents and prices are skyrocketing in cities large and small; racial and economic segregation is worsening as neighborhoods become increasingly exclusionary; climate pollution is rising as more and more communities get locked into sprawling car dependence.  

    And even local leaders who want to do the right thing are usually stuck in a tragedy of the commons similar to what impedes action on climate change: mutual progress on housing depends on all jurisdictions acting on zoning reforms together, so why stick your neck out and act alone? 

    Meanwhile, policymakers and planners will point out any and all possible problems that might arise from loosening restrictions, arguing that it’s just too risky. But they too have a massive blind spot: the ongoing harms that status quo exclusionary zoning is inflicting on Washingtonians already.  

    The damage caused by doing nothing—the housing crisis we can all see with our own eyes right now—dwarfs any presumed potential risks of taking statewide action to allow more basement and backyard homes. 

    Fourth time’s a charm? 

    This year, Washington lawmakers will have a fourth chance to take action on the housing crisis by passing a bill to boost the production of in-law apartments and backyard cottages. The best time to do that was three years ago, but the second-best time is now. Further delay will only serve to tighten Washington’s housing squeeze and make it even harder for residents throughout the state to find homes they can afford.

    Check here to stay informed about this and other Washington zoning reform bills for 2022.