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Washington lawmakers racked up some solid wins for housing abundance this year, passing bills to legalize co-living homes, increase parking flexibility, and revamp building codes for middle housing. 

These wins overcame the challenges of both a “short session” (only two-months long) and the risk of complacency following 2023, which became known as Washington’s “year of housing” in recognition of all the bills passed to help reduce the state’s housing shortage. 

Indeed, 2024 was not without casualties. Three bills to boost housing supply that didn’t survive: HB 1245 to legalize house lot splitting, HB 2160 to allow more homes near transit, and HB 2113 to establish local accountability for housing production. And the legislature still has much work to do on the other two pillars of housing policy: stability for tenants and subsidy for below-market rate homes. 

Still, in 2024, Washington achieved more on zoning reform bills than in any previous year other than 2023. And the debate and coalition building around the bills that died will create a more solid foundation for progress on them next year.  

Here’s a cheat sheet for the three key bills that passed, followed by sections digging into the details on each.  

  • HB 1998 establishes a new best-in-the-US standard for statewide zoning reform to allow co-living homes, which are small apartments with shared kitchens. Co-living is a low-cost housing option requiring no public subsidy that most cities have all but regulated out of existence.  
  • SB 6015 creates new statewide standards to give builders more flexibility in complying with local parking mandates. The first stand-alone parking bill ever passed in Washington, its reforms will make homebuilding easier and less expensive—especially for middle housing and accessory dwellings. 
  • HB 2071 sets in motion a process to modify the residential building codes so that it can apply to the construction of middle housing projects up to six units. It’s a critical cost-saving follow-up to 2023’s HB 1110 that legalized middle housing. 

Co-living homes: Naturally affordable, flexible, and community-forward  

Co-living homes are a low-cost, multifamily housing option in which each resident has a small, private room and shares with other building residents a common kitchen and other spaces. Policymakers also refer to it as single-room occupancy (SRO), congregate housing, or rooming houses.  Rents in newly constructed, market-rate co-living homes in the Puget Sound region can be affordable to people earning as low as 50 percent of area median income, without any public subsidy.  

Co-living was once far more common. In the 1950s, it accounted for up to 10 percent of the rental stock in some US cities. Soon after that, however, local governments began adopting restrictive zoning and other rules that increasingly banned co-living, both new and old, and its numbers plummeted.  

In a first for any US state, last year Oregon passed legislation to legalize co-living homes on all residential lots in urban areas. A weakness in Oregon’s bill, though, is that it doesn’t apply a co-living-specific method for counting its units—i.e., counting their “sleeping units” as fractions of standard “dwelling unit” apartments that they are so as to fit well within designated residential zones.

Washington’s co-living bill, HB 1998, raises the bar by establishing this better-suited unit-counting method and by establishing other guardrails to prevent cities from indirectly preventing co-living development. Here’s what it does (see this article for more details): 

  • Requires cities and counties to allow co-living homes everywhere that they allow multifamily housing with six or more units per lot on land inside urban growth areas (the six units aligns with the middle housing bill HB 1110) 
  • Prohibits a sleeping unit from counting as more than one-quarter of a dwelling unit for density limits 
  • Eliminates parking mandates within a ½-mile of a transit stop with at least 15-minute service; otherwise, caps mandates at 1 space per 4 sleeping units  
  • Caps sewer connection fees per sleeping unit at one-half of what’s charged for a standard dwelling unit 
  • Prohibits requirements for inclusion of standard apartments or commercial spaces, and for unfairly stringent design standards or review processes 
  • Cities and counties must comply by the end of 2025  

From 2014 to 2016 in Seattle, co-living homes accounted for fully 1 in 11 of total new homes built, before the city’s ill-advised raft of new restrictions effectively killed off co-living construction. Based on that precedent, by a conservative estimate the reforms required by the co-living bill could yield two to three thousand additional homes per year statewide in Washington. 

“This is a big step forward for affordable housing,” said Washington State Senator and sponsor of the bill Jesse Salomon. “We have seen a worrisome rise in senior homelessness, and many of our young adults are unable to afford housing near work or school. Co-living can offer clean, safe housing and a sense of community for people.” 

How co-living earned fast, strong bipartisan passage 

HB 1998 passed 96-0 in the House and 44-4 in the Senate, and on March 19, Governor Inslee signed it into law—a marvel in a short session that often becomes a bill-killing pressure cooker and for a bill whose central idea was brand new to legislators. Typically, legislators need at least a year or more to get comfortable voting for new bill concepts.  

Amendments slightly weakened a few of HB 1998’s original guardrails, but the most important provisions on density and parking—usually lightning rods for opposition—were untouched and remained strong. Where local governments cap dwelling unit density, the bill requires them to raise that cap by a factor of four for sleeping unit density. The parking mandate reductions are arguably the strongest parking reforms yet passed in Washington. 

So why did things go so well for HB 1998? Here are some factors that helped it sail through unscathed:  

  • Strong champions in both chambers: Representative Mia Gregerson and Senator Jesse Salomon both began working on the bill during the interim and collaborated closely all through the process. 
  • Bipartisanship: Representative Andrew Barkis, the Republican caucus’s leading voice on housing policy, engaged from the get-go on developing the bill with his colleagues across the aisle. 
  • It’s about bringing something back: The bill “re-legalizes” a type of housing that was once more common, and history shows that it provided an important, low-cost option. 
  • It can be good option for seniors: AARP supported the bill because co-living is a great option for single seniors who want to downsize, age in their communities, and benefit from the increased social interaction typical in co-living buildings.   
  • It provides unsubsidized affordable housing: Market-rate co-living rent is often as low as rents in standard below-market-rate apartments that require significant public subsidy. 
  • A strong coalition: HB 1998 enjoyed a broad coalition of support from housing, environmental, community, business, and builder advocates (see list here). Opposition was pretty much non-existent. Even the Association of Washington Cities (AWC), which historically has vehemently opposed any bill that supersedes local control of zoning, didn’t raise a fuss. 

Increased parking flexibility for housing by counting spaces people already use 

Most parking reform legislation aims to reduce requirements for new homes to include a pre-determined number of off-street parking spaces. SB 6015 is different. It instead gives builders more options on how to provide the parking local governments require. Not only was SB 6015 Washington’s first stand-alone parking reform bill to pass; it also establishes a model for statewide reform of local rules for parking configurations. 

“…If it’s a parking spot, it should count as a parking spot.”


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Senator Sharon Shewmake (D-Bellingham) stepped up to be the prime sponsor for this new approach. “This is not a bill getting rid of parking minimums,” she said. “The general idea is that if it’s a parking spot, it should count as a parking spot.”   

By setting state standards on what cities must count toward their parking mandates, SB 6015 reduces unnecessary expenses that overly prescriptive parking rules can add to housing construction. In some cases, this added flexibility on parking nuts and bolts can enable homebuilding that otherwise would have been impossible. SB 6015 will make it easier to build middle housing in particular, because it tends to have such tight geometrical constraints. 

Here’s what SB 6015 does in all cities and counties planning under Washington’s Growth Management Act: 

  • Prohibits requirements for parking spaces to be enclosed in a garage  
  • Allows existing gravel parking lots with up to six spaces to fully count toward parking minimums (paving not required)  
  • Allows parking areas to be surfaced with grass block pavers 
  • Allows space saving tandem parking spaces (where one car parks behind another) to fully count toward minimums  
  • Prohibits requirements for parking spaces to be larger than 8 by 20 feet (excepting accessible spaces) and grandfathers the legality of existing spaces regardless of their size 
  • Requires that if parking minimums and tree preservation requirements conflict for a homebuilding project, the tree rules take precedence; applies only to cities with over 6,000 residents (this provision was amended out of HB 2071 and later amended into SB 6015) 
  • Entirely exempts a one-mile radius around the airport in the city of SeaTac (by the city’s request), piggybacking off of the same exemption in the 2023 middle housing bill

At SB 6015’s hearings, builders testified on why the bill’s reforms would matter. “My work is made much more difficult by inflexible parking requirements that prioritize cars over people,” homebuilder Keven Maas told lawmakers. Mount Vernon, where he lives, requires a two-car garage with every new house, in most cases. For a duplex, the mandate balloons to two double garages.  

“On small infill lots, I find there’s enough room on the ground floor to build a bedroom for two people or a bedroom for two cars, but not both.”


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Not only does a garage add about $50,000 to the cost of construction, it also can make the homes less accessible. “On small infill lots, I find there’s enough room on the ground floor to build a bedroom for two people or a bedroom for two cars, but not both,” Maas said. “Garages can’t go upstairs, so we make people climb stairs.” SB 6105 will enable more new homes with bedrooms on the ground floor, a preference Maas anticipates will increase along with Washington’s growing senior population.  

A common scenario in which allowing tandem parking can make a big difference is with standard house driveways. Local rules often do not allow tandem parking in driveways to count toward the lot’s off-street quota for anything other than detached homes or duplexes. In particular, that can be a deal breaker for infill housing, including backyard cottages and other accessory dwelling units (ADUs), where the only space available to add parking spaces is an existing driveway.  

Large apartment buildings can also benefit. The 280-unit Arete co-living building in downtown Kirkland has 192 tandem stalls in its underground parking garage. Management pairs residents who want to share a tandem space for a reduced price. According to Arete’s developer Angela Rozmyn, who testified in support of SB 6015, tandem parking consumes 12 to 15 percent less garage space than standard single stalls. In Arete, that enabled elimination of one-half of a garage level, reducing costs for steel, concrete, and excavation. The costly, time-consuming city waiver process Rozmyn had to go through to put in tandem parking will be a thing of the past under SB 6015

As for its path through the legislature, SB 6015 passed on a nearly partisan 30-19 vote in the Senate, followed by a bipartisan 96-1 vote in the House. The passed version was missing several provisions in the bill as introduced that were opposed by the AWC and amended out by the Senate Local Government committee. One would have allowed on-street parking in front of a lot to count toward the lot’s off-street parking minimums—likely the most impactful part of the original bill. Another would have allowed parking in property setbacks to count. 

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  • Not all cities agreed with the AWC on watering down the original bill. Vancouver, the fourth-largest Washington city, proposed the bill remove parking minimums for middle housing altogether. “Vancouver supports this bill,” Councilmember Ty Stober testified, “but quite frankly it does not go far enough in releasing our state from the shackles of parking.”  

    Better building codes: A necessary follow-up to 2023’s HB 1110 for middle housing 

    HB 2071 gets at a key piece of the housing policy puzzle that hasn’t gotten as much attention as zoning: building codes. Building codes are essential for making sure housing doesn’t fall over or burn down, but in some cases, they needlessly add construction costs.  

    In most jurisdictions, the residential building code applies to single-detached houses and duplexes. But for triplexes and up, builders must adhere to the far more stringent commercial building code—the same code that was designed to regulate skyscrapers. Requiring such an onerous and expensive code for middle housing is overkill, given how it’s the same wood frame construction type and scale as a house. What’s more, as with exclusionary zoning, a century ago some advocates for more onerous building codes on multifamily housing were motivated by their desire to ban apartment buildings

    Building code reform for middle housing has recently started getting more attention. Last year saw the first statewide reform when North Carolina passed HB 488, instructing the Building Code Council to modify the residential code for up to fourplexes. In 2022, Memphis and Shelby County, Tennessee, became the first major US jurisdictions to move middle housing into the residential building code, but the change has been on hold due to concerns from the state fire marshals. Tennessee currently has a state bill in play. In January of 2024, Anchorage, Alaska, passed the third in a series of ordinances that remove from their regulations various barriers to triplexes and fourplexes and align their middle housing building codes with the less onerous residential building code. 

    In 2023, Washington passed HB 1110 to make sure zoning allows middle housing, but the cost and hassle of the commercial building code is still a big barrier to it actually getting built. To address that issue, in the same session, Representative Davina Duerr introduced a bill,HB 1167, that would have instructed the State Building Code Council (SBCC) to modify the residential building code so that it applies to middle housing with up to six units. The bill was uncontroversial, passing 95-0 in the House, but then died when the Senate declined to give it a floor vote.  

    In 2024, Rep. Duerr came back with HB 2071, which repeats HB 1167’s language on applying the residential code to middle housing. It was a mixed bag on bipartisanship, passing 63-34 in the House and 36-13 in the Senate. 

    HB 2071 also includes a second building code reform intended to enable the construction of low-cost, efficiently designed, small studio apartments. The bill instructs the SBCC to evaluate a reduction of the minimum habitable space for studios. As described in this article, the widely used International Building Code arbitrarily prohibits small, efficient home designs. The bill’s intent is for Washington to reduce its minimum habitable space to align with the National Healthy Housing Standard. 

    The original bill’s allowance for external insulation for Passive House retrofits and construction to extend into setbacks was unfortunately amended out in committee. And its provision to prioritize tree protection over parking mandates was amended into SB 6015 (see above). 

    In 2024, Washington also passed a related bill to streamline the process for improving the state building code. SB 6291 updates SBCC rules for amendment criteria, timelines, adoption cycle, councilmember selection, and technical advisory groups. 

    Onward to 2025 

    While the success of Washington’s 2023 legislative session earned it widespread praise as the “Year of Housing,” the work was far from done. Lawmakers in 2024 followed up with more, complementing 2023’s wins with bills to re-legalize co-living homes, allow more flexibility in how cities meet parking mandates, and update building codes to permit more middle housing options.  

    Not enough progress to qualify as “Year of Housing 2.0” as some had hoped, but solid progress, especially given the limits of a short session. And the work on housing bills that died will keep the momentum building for next year and beyond—to unlock more homes, in all shapes and sizes, for Washingtonians throughout the state. We’ve not seen the last of bills on transit-oriented development, lot splitting, parking, housing production accountability, and more.