Get Ready for Multiplexes and ADUs

Babak Shamsi Edmonds Lawyer

In 2023, Washington State passed laws regarding Accessory Dwelling Units (HB 1337) and multiplexes (HB 1110) to create a systematic and comprehensive change in the availability of housing. These house bills establish general requirements that municipalities must follow, and which present developers and contractors with unique opportunities to take advantage of a vast change in housing regulations that will, almost undoubtedly, result in a flurry of construction.

In general, HB 1337 requires adoption or amendment of municipal zoning regulations to allow at least two Accessory Dwelling Units (“ADUs”) on all lots in an urban growth area with single family homes, while HB 1110 requires cities to allow the building of duplexes, fourplexes, and/or sixplexes depending on population and other considerations.  My partner, William Kessler, previously posted about Washington State HB 1337 on ADUs here, while I posted about HB 1110 regarding multiplexes here and here. These articles outline in more detail the requirements that municipalities and cities must meet to comply with the new state laws. 

Both HB 1337 and HB 1110 require compliance by municipalities and cities by no later than six months from completion of their next Comprehensive Plan update. While the general rule does not differ, each city and municipality has its own timeline for a Comprehensive Plan update, so the changes will arrive on a rolling basis from area to area. In any case, the changes will come sooner rather than later, and discussions have already started across the State of Washington on the impact of these laws. 

Edmonds, for example, has already started working on its Comprehensive Plan update, which it will complete in 2024, and which addresses, among other things, considerations pertaining to both HB 1337 and HB 1110, as well as exploring incentives to developers to build neighborhood centers and hubs. Meanwhile, Seattle has tentatively set completion of its Comprehensive Plan for the Fall of 2024, but the details have largely yet to emerge. 

Ultimately, these developments (pun intended) will likely result in significant opportunities for developers and general contractors to become a part of interesting, exciting, and desirable building projects over the coming years. Indeed, it presents a possible sea change that does not come regularly, and developers and contractors should act quickly to start putting together the contracts necessary to get projects in place, as well as making sure to line up deposits from clients. Owners, similarly, will want to have their goals sorted out, and retain their contractors, because options will become limited as contractors and developers become busier and busier. In other words, the construction market may soon become more robust and competitive.

If you are a property developer, contractor, or homeowner looking for assistance with the preparation and review of contracts, or simply guidance in any matters pertaining to real estate and construction, the lawyers at Beresford Booth remain prepared to assist you.

To learn more about Multiplexes and ADUs, please do not hesitate to contact us at or by phone (425) 776-4100.

BERESFORD BOOTH PLLC has made this content available to the general public for informational purposes only. The information on this site is not intended to convey legal opinions or legal advice.