SENATE BILL REPORT
SB 5332
As of February 26, 2025
Title: An act relating to mobile dwellings.
Brief Description: Concerning mobile dwellings.
Sponsors: Senators Shewmake, Wilson, J., Bateman, Chapman, Nobles and Valdez.
Brief History:
Committee Activity: Housing: 1/29/25, 1/31/25 [DPS-WM, w/oRec].
Ways & Means: 2/26/25.
Brief Summary of First Substitute Bill
  • Requires any city or county planning under the Growth Management Act to allow at least one mobile dwelling unit on each lot zoned for residential use if certain conditions are met.
SENATE COMMITTEE ON HOUSING
Majority Report: That Substitute Senate Bill No. 5332 be substituted therefor, and the substitute bill do pass and be referred to Committee on Ways & Means.
Signed by Senators Bateman, Chair; Alvarado, Vice Chair; Orwall, Salomon and Trudeau.
Minority Report: That it be referred without recommendation.
Signed by Senators Goehner, Ranking Member; Gildon.
Staff: Melissa Van Gorkom (786-7491)
SENATE COMMITTEE ON WAYS & MEANS
Staff: Trevor Press (786-7446)
Background:

Growth Management Act.  The Growth Management Act (GMA) is the comprehensive land use planning framework for counties and cities in Washington. The GMA establishes land use designation and environmental protection requirements for all Washington counties and cities. The GMA also establishes a significantly wider array of planning duties for 28 counties, and the cities within those counties, that are obligated to satisfy all planning requirements of the GMA. These jurisdictions are sometimes said to be fully planning under the GMA.

 

Counties that fully plan under the GMA are required to designate urban growth areas (UGAs) within their boundaries sufficient to accommodate a planned 20-year population projection range provided by the Office of Financial Management. Each city located within a planning county must be included within a UGA.  Urban growth must be encouraged within the UGAs, and only growth that is not urban in nature can occur outside of the UGAs.

 

Common Interest Communities.  A common interest community (CIC) is a form of real estate in which each unit owner or homeowner has an exclusive interest in a unit or lot and a shared or undivided interest in common area property. In Washington, several statutes govern residential CICs, such as condominiums and homeowners' associations. These groups can regulate or limit the use of property by its members.

Summary of Bill (First Substitute):

A mobile dwelling unit (MDU) is a vehicular-type unit primarily designed for recreational camping or travel use that has its own motive power or is mounted on or towed by another vehicle, including travel trailers, fifth-wheel trailers, folding camping trailers, truck campers, tiny houses with wheels, and motor homes.

 

Any city or county planning under the GMA must allow at least one MDU on each lot zoned for residential use if the lot is: 

  • located within a UGA and has at least one existing housing unit;
  • a property where the city or county and the utilities have determined that the additional demand will be adequately served by sewer systems; and
  • not located in designated critical areas and natural resource lands, or a shoreline of the state.

 

The MDU must:

  • be connected to electrical services through a dedicated outlet;
  • be maintained so that it can be moved at any time;
  • meet the setback requirements of the underlying zone; and
  • if the MDU has internal plumbing, be connected to potable water and sanitary sewer services, or if the MDU does not have internal plumbing, the occupant must have 24- hour, 7 days a week access to potable water, toilets, and showers in the existing housing unit on the lot.

 

Cities and counties must enforce standard inspection procedures for utility hookups to mobile dwelling units but may not require inspection of the MDU itself.  Cities and counties may inspect storage tanks, sewer, and sanitary connections to ensure they are not leaking or polluting.

 

A CIC may not create a restriction, covenant, condition, declaration, bylaw, rule, provision of governing document, or master deed provision that prohibits at least one MDU on each lot zoned for residential property within a city subject to the act. 

EFFECT OF CHANGES MADE BY HOUSING COMMITTEE (First Substitute):
  • Updates the conditions to require the lot is a property the city or county and utilities have determined that additional demand will be adequately served by sewer systems, rather than restricting a mobile dwelling unit on a property on which the city or county has determined that housing development cannot be adequately served by water, sewer, stormwater, or transportation systems. 
  • Requires a water connection made through a yard hydrant or anti-siphon hose bib be certified for potable use.
  • Requires the mobile dwelling unit occupants have 24-hour, seven days a week access to potable water, toilets, and showers in an existing housing unit on the lot if the unit does not have internal plumbing.
  • Allows cities and counties to inspect storage tank, sewer, and sanitary connections to ensure they are not leaking or polluting.
  • Requires the mobile dwelling unit be maintained so that it can be moved at any time.
  • Requires the mobile dwelling unit meet the setback requirements of the underlying zone.
  • Adds tiny house with wheels to the list of units included under the mobile dwelling unit definition.

Appropriation: None.
Fiscal Note: Available.
Creates Committee/Commission/Task Force that includes Legislative members: No.
Effective Date: Ninety days after adjournment of session in which bill is passed.
Staff Summary of Public Testimony on Original Bill (Housing):

The committee recommended a different version of the bill than what was heard. PRO:  Current housing solutions are insufficient because they are not addressing supply for lower cost housing options that can be truly affordable at market rate without government subsidy. MDUs are far less expensive and more rapidly deployed than any type of housing.  These homes are built to Labor and Industries standards and legal to use in a mobile home or RV park.  This bill expands the areas in which this type of housing is allowed and requires the same infrastructure.  This bill allows for people to lean on family members that might be able to offer parking at a rate that is better than traditional RV communities, some of which have predatory fees.  People are in moldy rentals with no other housing options and this is an affordable option for people to own a space that they can take care of instead of relying on a landlord.  The more restrictions you put on could limit the amount of housing that gets created.  People will have an easier time going to work, staying sober and healing from trauma if they have a safe space to live.  Oregon has already implemented this type of housing and it has been successful in providing housing.  This bill will provide a pathway to homeownership and stable housing for low income individuals, students, seniors and working families.  This also allows intergenerational families to stick together and have support while having separate living spaces.

 

CON:  Support innovative approaches to help with housing but do have significant public health concerns.  Without inspections of the mobile dwellings we have no way of knowing if the onboard systems are in an adequate condition to be able to contain or transfer the waste.  There is also no way to validate whether potable water, toilets and showers are being provided by the existing unit on the lot.  Also concerned that the language "at least one" may have the unintended consequence of allowing short term rental situations or ad hoc mobile home parks in areas that are not well suited to accommodate these vehicles and uses.

 

OTHER: Support the intent but are concerned with the impact it could put on existing systems because mobile dwellings use pressure which poses a risk of back pressure and the requirements in the bill would not meet the Department of Health standards as part of the Cross Connection Program.  Allowing trailers to connect directly to sewers via cleanouts could increase risk for the existing infrastructure and environment when or if there is a backup.  Having the connection below ground and not just through the standard cleanout would be a safer approach. 

Persons Testifying (Housing):

PRO: Kol Peterson, Tiny Hookups LLC; Dan Bertolet, Sightline Institute; Zachariah Giffin, Operation Tiny Home - Non Profit; Allison Arroyo; Jean Gamman; Tim McCormick; Lisa Tenney, HomeMindBody.con; Michelle Boyle, Self; Mckellips Todd, Wa tiny house association; Alaska Wagoner; Lauren Grey.

CON: Kelsey Hulse, Washington State Association of Counties.
OTHER: Joren Clowers, Sno-King Water District Coalition.
Persons Signed In To Testify But Not Testifying (Housing): No one.
Staff Summary of Public Testimony (Ways & Means):

PRO: SB5332 presents a viable solution to the housing crisis by offering an affordable, low-cost housing option. Mobile dwellings, specifically tiny homes and MDUs, are an essential form of housing for people who are underserved by current housing markets. These units provide flexibility, climate change adaptation, and disaster resiliency without requiring public subsidies. The bill extends existing regulations for MDUs in RV parks to residential properties, ensuring that these units are safely installed with proper infrastructure. There is already evidence from Portland that MDUs can be successfully integrated into residential areas without complaints. The bill also allows cities more options for addressing housing needs without mandating them to implement MDUs.

 

CON: This bill raises significant concerns about public health and safety, particularly regarding the potential for temporary structures like RVs and tents to be treated as permanent residences. There is no clear mechanism for local governments to inspect these units, which could lead to deteriorating conditions such as mold and other hazards. Additionally, the lack of safeguards against short-term rentals could result in investors benefiting rather than renters. Cities also express concerns about the administrative burden, with local governments lacking the resources to manage code enforcement and ensure compliance with safety standards. Furthermore, the bill could lead to environmental issues, with unregulated hookups potentially causing contamination of critical areas.

 

This bill creates potential complications for city planning. The bill’s proposal to allow additional units on every residential parcel in the state could complicate zoning and planning requirements, particularly regarding the installation of utilities. While temporary structures like tiny homes on wheels might be acceptable in RV parks, the expansion to residential properties raises issues regarding the enforcement of safety standards, including the proper installation of hookups for water, electricity, and sewage. The proposed changes could have significant impacts on local governments and public health, and further refinement of the bill might be necessary.

Persons Testifying (Ways & Means):

PRO: Dan Bertolet, Sightline Institute; Kol Peterson; Tim McCormick; Zachariah Giffin, Operation Tiny Home; Todd McKellips, WA tiny house association.

CON: Carl Schroeder, Association of Washington Cities; Kerri Burnside, Bellingham Tenants Union; Michael Mactutis, City of Kent, Public Works Department.
Persons Signed In To Testify But Not Testifying (Ways & Means): No one.