On February 28, 2025, Washington’s State Senate passed Senate Bill 5559, a housing supply measure which proposes to apply more uniformity in the procedures that local governments use for Unit Lot Subdivision (“ULS”) processes. Professional housing providers, builders, and homeowners alike can use ULS processes to bring townhouses, cottage housing, and even accessory dwelling units to market. With the Senate’s bipartisan and nearly unanimous approval, this bill will now move to Washington’s State House of Representatives for consideration in that chamber.
In the midst of an acute housing supply and affordability crisis that spans our region, many cities and towns in Washington State already make bold and effective use of ULS procedures—within areas designated for growth—to help provide new family-sized housing units in configurations of twos, fours, nines or even more, depending on the local jurisdiction’s rules and the features of the underlying land. However, because the ULS is a relatively new tool, cities and towns have been trying different approaches at different paces, occasionally leading to confusion and uncertainty. Some cities and towns have not enacted ULS procedures at all. SB 5559 seeks to help housing providers and cities alike by clarifying a baseline framework for ULS processes across different jurisdictions.
Among other things, the Senate’s adopted bill text provides that a city or town’s ULS procedures (i) must not require any public predecision meeting or hearing, or any non-administrative design review; (ii) must apply only clear and objective design and development standards; (iii) must be logically integrated with any other application review and approval processes that apply; and (iv) must be subject to applicable deadlines for the local government’s permit reviews and decisions.
Notably for proponents of ADU/DADU “lot splits” within Seattle’s city limits, the Senate’s draft text would not affect the City of Seattle’s current exclusion of ADUs and DADUs from its ULS procedures. Observers have suggested that this bill could be amended to add a solution for that specific housing barrier, so further discussion of these concepts in the House is likely.
Sen. Liz Lovelett (D-Anacortes) introduced the bill as its prime sponsor, with co-sponsorship by Sen. Nobles (D-University Place) and Sen. Trudeau (D-Tacoma). The bill passed out of the Senate with 48 votes in favor, none opposed, and one absence. In the House, it will first be reviewed by the Local Government Committee under Chair Davina Duerr (D-Bothell) and ranking GOP member Mark Klicker (R-Walla Walla).
Please do not hesitate to contact HCMP’s real estate and land use attorneys with any questions about how this legislation or other bills being considered in Olympia may affect a current housing proposal or may expand the possibilities for future infill uses or development on your property.
