Washington legislation · 2025-26 Regular Session
Washington SB5470: Detached ADUs
Status: In committee, February 26, 2026
Establishing limitations on detached accessory dwelling units outside urban growth areas.
What the bill says
An act Relating to establishing limitations on detached accessory dwelling units outside urban growth areas; amending RCW 36.70A.696; and adding a new section to chapter 36.70A RCW. NEW SECTION.
From the introduced text:
AN ACT Relating to establishing limitations on detached accessory dwelling units outside urban growth areas; amending RCW 36.70A.696; and adding a new section to chapter 36.70A RCW. NEW SECTION. Sec. 1. A new section is added to chapter 36.70A RCW to read as follows: (1) Counties may allow detached accessory dwelling units outside of urban growth areas if the county meets the requirements in subsection (2) of this section, and such detached accessory dwelling units are subject to development regulations that include the following (b) The detached accessory dwelling unit is subject to the water supply requirements of RCW 19.27.097 and any groundwater mitigation requirements adopted by the county or department of ecology; (c) The applicant must provide documentation that the existing or proposed sewage or septic system is capable of handling the additional demand placed upon it by the detached accessory dwelling unit; (d) The gross floor area of the detached accessory dwelling unit may not exceed the gross floor area of what could be authorized by the county as an expansion of the primary dwelling to create an attached accessory dwelling unit and, in no case, exceed 1,296 square feet. Floor areas exclude garages, porches, and unfinished basements; (e) The detached accessory dwelling unit must utilize the same driveway as the principal unit; (f) The detached accessory dwelling …
Sponsors
- Keith Goehner (R) · primary sponsor
- Jessica Bateman (D)
- Mike Chapman (D)
- Noel Frame (D)
- Chris Gildon (R)
- T'wina Nobles (D)
- Rebecca Saldaña (D)
Latest actions
- : Senate Rules "X" file.
- : Placed on second reading by Rules Committee.
- : Passed to Rules Committee for second reading.
- : HSG - Majority; 2nd substitute bill be substituted, do pass.
- : Executive action taken in the Senate Committee on Housing at 10:30 AM.
- : Public hearing in the Senate Committee on Housing at 10:30 AM.
- : Rules Committee relieved of further consideration. On motion, referred to Housing.
- : By resolution, reintroduced and retained in present status.
- : Senate Rules "X" file.
- : Placed on second reading by Rules Committee.
Votes
- Senate Committee on Housing: That Second Substitute Senate Bill No. 5470 be substituted therefor, and the second substitute bill do pass (February 4, 2026): 7 yea, 0 nay, passed
- Senate Committee on Ways & Means: That it be referred without recommendation (February 20, 2025): 22 yea, 0 nay, passed
- Senate Committee on Housing: That Substitute Senate Bill No. 5470 be substituted therefor, and the substitute bill do pass (February 12, 2025): 7 yea, 0 nay, passed
Subjects: HOUSING AND HOMES, GROWTH MANAGEMENT
Common questions
- What is SB5470?
- SB5470 is a bill in the Washington Legislature (2025-26 Regular Session): Detached ADUs.
- What does SB5470 do?
- In its own words: An act Relating to establishing limitations on detached accessory dwelling units outside urban growth areas; amending RCW 36.70A.696; and adding a new section to chapter 36.70A RCW. NEW SECTION.
- What is the status of SB5470?
- In committee as of February 26, 2026. Latest action: Senate Rules "X" file. (February 26, 2026).
- Who sponsored SB5470?
- Keith Goehner (R), with 6 co-sponsors.
- Where is the official record for SB5470?
- On the Washington Legislature website: https://app.leg.wa.gov/billsummary?BillNumber=5470&Year=2025
Source: official Washington record. Tracked by Delilah, AI for legislation across all 50 states and Congress.