HB 1345 Washington House · 2025-2026 Regular Session

Establishing limitations on detached accessory dwelling units outside of urban growth areas.

HB 1345 restricts detached accessory dwelling units (ADUs) - separate small homes on the same lot as a main house - outside urban growth areas in Washington counties. It requires counties to limit each parcel to one ADU, set size limits (max 1,296 sq ft), mandate water metering and sewage capacity documentation, and require ADUs to be within 150 feet of the main home. Counties must enforce penalties for unpermitted ADUs (including $1,000 fines, removal orders, and 3-year permit bans) and track ADU permits for land-use planning updates. The bill applies only to counties allowing such ADUs outside urban areas, not affecting existing urban or rural ADU rules.

Issues: ✗ Housing

Bill status signed all 5 stages cleared

Introduction

Jan 2026

Committee Review

Feb 2026

House Passage

Mar 2026

Senate Passage

Mar 2026

Signed into Law

Mar 2026

Introduced Jan 12, 2026 Signed Mar 27, 2026

Maddy AI version diff · 2 comparisons

What changed between versions

Engrossed Bill → Passed Legislature · 2 edits

MINOR

The bill text was updated to reflect its successful passage by both the House and Senate in the 2026 Regular Session, replacing the previous 2025 session reference. This change formalizes the bill's final status and ensures the correct legislative session is cited for future implementation.

Scope change

The bill's scope remains unchanged as this is a procedural update to the certification of enrollment.

TIMELINE

The legislative session was updated from the 2025 Regular Session to the 2026 Regular Session to match the actual dates the bill was passed by the legislature.

TECHNICAL

New certification text was added to formally document that the House and Senate approved the bill on specific dates in 2026.

Floor votes · Senate Mar 3, 2026 · House Jan 22, 2026

How they voted

35–15

Passed · 1 other

Total votes 51

Mar 3, 2026

D Democratic31

30 Yea 1

96% Yea

R Republican20

5 Yea 15 Nay

75% Nay

Vote distribution

All Yea All Nay Mixed No data

Full legislative history

Actions timeline

Total actions

Key actions

Committee

Mar 27, 2026

Signed into law

Governor signed.

executive

Mar 4, 2026

Upper · Passed

President signed.

upper

Mar 4, 2026

Lower · Passed

Speaker signed.

lower

Mar 3, 2026

Senate · Passed

Senate Vote: pass (35-15-1)

senate

Feb 18, 2026

Upper · Passed

HSG - Majority; do pass.

upper

Feb 18, 2026

Upper · Passed

Executive action taken in the Senate Committee on Housing at 10:30 AM.

upper

Feb 4, 2026

Upper · Passed

Public hearing in the Senate Committee on Housing at 10:30 AM.

upper

Jan 22, 2026

Lower · Passed

Floor amendment(s) adopted.

lower

Jan 12, 2026

Introduced

By resolution, reintroduced and retained in present status.

lower

Feb 10, 2025

Committee

Referred to Rules 2 Review.

lower

Feb 6, 2025

Lower · Passed

HOUS - Majority; do pass.

lower

Feb 6, 2025

Lower · Passed

Executive action taken in the House Committee on Housing at 8:00 AM.

lower

Jan 27, 2025

Lower · Passed

Public hearing in the House Committee on Housing at 1:30 PM.

lower

1 primary · 4 co-sponsors