Super exciting (if somewhat nerdy) policy news: the Washington State legislature just took two big steps to increase the availability of “missing middle” housing through a pair of new housing bills: HB 1337 and HB 1110. These bills will increase the availability of affordable housing options and reduce barriers to building ADUs, DADUs, and other forms of housing. Both bills passed the legislature with strong bipartisan support – housing is an important issue for all Washingtonians. Here’s what you need to know:

HB 1337: Better ADU Rules for All of Washington

HB 1337 will make it easier for Washington homeowners to add ADUs to their properties by eliminating some of the biggest regulatory barriers in most cities and towns in the state, including all of King, Pierce, and Snohomish counties. 

What does it do?

These are some of the most significant changes the bill will make to existing ADU regulations:

  • Eliminating owner-occupancy requirements
  • Legalizing two ADUs per lot in any combination of attached or detached 
  • Increasing the maximum ADU size to 1,000 sq. ft. 
  • Allowing the primary home and ADU to be sold separately via condoization
  • Eliminating off-street parking requirements for ADUs within a half mile of major transit stops
  • Capping impact fees at 50% of the fees that would be paid for a new primary dwelling

Special note for homeowners in Seattle, Kirkland, and Burien: your cities already have great ADU rules in place (give yourself a high five!), so these changes won’t affect you as much.

When will it go into effect?

Some cities may move more quickly, but the new ADU rules aren’t technically required until six months after each city’s next update to its Comprehensive Plan. For King, Pierce, and Snohomish counties, that generally means late 2024 to early 2025.  

I’m thinking about an ADU. Should I wait to build?

Don’t wait! Most of the cities in our region have pretty flexible ADU rules already (ahem, ahem, Bellevue…), so for homeowners who build ADUs now, the main impact of the new rules will be some added flexibility in resale and occupancy–in other words, an ADU built today will become even more valuable under the new rules. As we’ve written before, ADUs are still a great investment, especially if you already own the property – and when the HB 1337 rules go into effect statewide, we expect an ADU construction boom, which will slow down permitting and delivery for a while. Get your ADU project done before the rush begins!

HB 1110: Increased Housing Supply and Density

HB 1110 aims to increase housing supply and density by allowing the construction of more dwellings (like ADUs, cottages, duplexes, triplexes, and townhomes) in most areas currently zoned for single-family homes. This bill applies primarily to cities with a population above 75,000 – like Seattle, Bellevue, Auburn, Federal Way, Kent, Kirkland, Renton, and Tacoma – with some less significant requirements that will apply to most of the smaller cities in King County. It’s important to note that some existing city rules, like lot coverage, setbacks, and critical areas, will still apply – so even though most single-family properties will become technically eligible for additional density, it might not always be feasible to build.

What does this mean for ADUs?

Cities have some flexibility to choose how they enact the new density rules under HB 1110 – but since ADUs count toward the number of dwellings per property and every city will be required to allow 2 ADUs under HB 1337, ADUs are going to be an even more important piece of the puzzle. If you’re considering a multi-dwelling development, the MyKabin sales team can help develop a plan for your property that balances an ADU (or ADUs) today and additional homes in the future.

Creating More Livable and Sustainable Communities

These bills are important steps toward increasing housing availability and affordability and reducing urban sprawl. We are super excited to see the state taking steps to address the housing shortage and create more livable and sustainable communities. As the Seattle region’s largest dedicated builder of backyard homes, MyKabin is committed to helping homeowners take advantage of these new opportunities and find the housing solutions they need. Contact us to learn more and get your ADU project started.

By |Published On: May 5, 2023|