SB 5332 Washington Senate · 2025-2026 Regular Session

Concerning mobile dwellings.

SB 5332 allows cities and counties in Washington to permit at least one mobile dwelling unit (like tiny homes on wheels, travel trailers, or RVs) on residential lots that already have a home, are in urban growth areas, and have adequate utility capacity. It requires safe utility connections (water, sewer, electricity) to existing homes on the lot and bans homeowners' associations from prohibiting these units, though the rule expires in 2028. The bill does not require new construction but sets standards for how mobile dwellings must be connected to utilities and maintained to remain movable. This directly affects local governments, property owners with existing homes, and HOAs in qualifying areas.

Issues: ✓ Housing

Bill status in committee 1 of 4 stages cleared

Introduction

Jan 2026

Committee Review

Floor Vote

Governor

Introduced Jan 12, 2026 Last action Jan 12, 2026

Maddy AI version diff · 1 comparison

What changed between versions

Bill → Substitute Bill · 8 edits

MODERATE

The bill was amended to broaden the definition of allowed mobile dwellings to include 'tiny houses with wheels' and add specific setback requirements. The eligibility criteria for placing these units were tightened by requiring that sewer systems be explicitly certified to handle the additional demand and by excluding units located in state shorelines or critical natural resource lands. Additionally, the inspection rules were expanded to allow local officials to check for leaks or pollution from storage tanks and utility connections.

Scope change

The bill's scope was expanded to include a new category of mobile dwelling units (tiny houses with wheels) and to apply stricter environmental and infrastructure constraints.

DEFINITION

Added 'tiny houses with wheels' to the list of units that qualify as mobile dwelling units under the new law.

ELIGIBILITY

Replaced the general requirement that infrastructure must 'adequately serve' the property with a stricter mandate that utilities must determine the additional demand will be 'adequately served by sewer systems'.

Added a prohibition on placing mobile dwelling units in state shorelines or critical areas and natural resource lands.

REQUIREMENT

Added a requirement that mobile dwelling units must meet the setback requirements of the underlying residential zone.

Added a requirement that mobile dwelling units must be maintained so they can be moved at any time.

Clarified that water and sewer connections must use hoses and fittings certified for potable use.

Specified that access to water, toilets, and showers for units without internal plumbing must be available 24 hours a day, seven days a week.

ENFORCEMENT

Expanded the inspection authority for cities and counties to include checking storage tanks and utility connections for leaks or pollution.

Floor votes

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Full legislative history

Actions timeline

Total actions

Key actions

Committee

Jan 12, 2026

Introduced

By resolution, reintroduced and retained in present status.

upper

Feb 26, 2025

Upper · Passed

Public hearing in the Senate Committee on Ways & Means at 1:30 PM.

upper

Feb 3, 2025

Committee

Referred to Ways & Means.

upper

Jan 31, 2025

Upper · Passed

Minority; without recommendation.

upper

Jan 31, 2025

Committee

And refer to Ways & Means.

upper

Jan 31, 2025

Upper · Passed

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

upper

Jan 29, 2025

Upper · Passed

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

upper

1 primary · 5 co-sponsors