House Bill 1337 - ADUs

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UPDATE: On June 24, 2025, the Renton City Council adopted the amendments to Renton Municipal Code to comply with Washington State mandates for accessory dwelling units. Please note it typically takes 3-4 weeks for these updates to be reflected online and in Renton Municipal Code. In the interim, please refer to the linked ordinance which shows all code changes.

For information about implementation of HB 1337 and online resources, please see RentonWA.gov/housingleg.

(Updated 7/14/2025)

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The Washington State legislature adopted new rules and regulations for Accessory Dwelling Units (ADUs) to expand housing opportunities.

An ADU is a dwelling unit on the same lot as a single-family, duplex, triplex, townhome, or other housing unit. It is a typical residential home with a kitchen, bedroom(s), and bathroom(s).

Cities across the state, including Renton, are required to update their local ADU regulations to comply with House Bill (HB) 1337 by June 30, 2025. See the table below for a summary of the current and future ADU requirements.

ADU architectural plans will continue to be offered through the city’s Permit Ready ADU Program for properties within Renton city limits. Please use the address locator and jurisdiction finder or contact Planning Customer Service to verify eligibility.

UPDATE: On June 24, 2025, the Renton City Council adopted the amendments to Renton Municipal Code to comply with Washington State mandates for accessory dwelling units. Please note it typically takes 3-4 weeks for these updates to be reflected online and in Renton Municipal Code. In the interim, please refer to the linked ordinance which shows all code changes.

For information about implementation of HB 1337 and online resources, please see RentonWA.gov/housingleg.

(Updated 7/14/2025)

----------------------------------------------------------------------------------------------------------------------------------------

The Washington State legislature adopted new rules and regulations for Accessory Dwelling Units (ADUs) to expand housing opportunities.

An ADU is a dwelling unit on the same lot as a single-family, duplex, triplex, townhome, or other housing unit. It is a typical residential home with a kitchen, bedroom(s), and bathroom(s).

Cities across the state, including Renton, are required to update their local ADU regulations to comply with House Bill (HB) 1337 by June 30, 2025. See the table below for a summary of the current and future ADU requirements.

ADU architectural plans will continue to be offered through the city’s Permit Ready ADU Program for properties within Renton city limits. Please use the address locator and jurisdiction finder or contact Planning Customer Service to verify eligibility.

Ask questions or add comments about House Bill 1337

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  • Share If you have a single family house with a mother in law in the basement, what is needed to make it a legal ADU? on Facebook Share If you have a single family house with a mother in law in the basement, what is needed to make it a legal ADU? on Twitter Share If you have a single family house with a mother in law in the basement, what is needed to make it a legal ADU? on Linkedin Email If you have a single family house with a mother in law in the basement, what is needed to make it a legal ADU? link

    If you have a single family house with a mother in law in the basement, what is needed to make it a legal ADU?

    Stella Michael asked 4 months ago

    Hi there! Please send property specific questions to PlanningCustomerService@rentonwa.gov with the property address so we can confirm that you are in the city's jurisdictional boundary. Thank you!

  • Share We started a permit for an ADU November of 2024. The home is still not complete and the county is charging us full impact fees because we applied for the permit prior to July 2025. Are they able to charge excessive fees for the adu? on Facebook Share We started a permit for an ADU November of 2024. The home is still not complete and the county is charging us full impact fees because we applied for the permit prior to July 2025. Are they able to charge excessive fees for the adu? on Twitter Share We started a permit for an ADU November of 2024. The home is still not complete and the county is charging us full impact fees because we applied for the permit prior to July 2025. Are they able to charge excessive fees for the adu? on Linkedin Email We started a permit for an ADU November of 2024. The home is still not complete and the county is charging us full impact fees because we applied for the permit prior to July 2025. Are they able to charge excessive fees for the adu? link

    We started a permit for an ADU November of 2024. The home is still not complete and the county is charging us full impact fees because we applied for the permit prior to July 2025. Are they able to charge excessive fees for the adu?

    Aleta G asked about 2 months ago

    Hi there! You submitted your inquiry without contact information, so we are unable to follow-up. Send property specific questions to PlanningCustomerService@rentonwa.gov and please be sure to provide the building permit number and/or property address. Thank you!

  • Share We're now 12 days past the implementation deadline and I don't see anything about Renton's new regulations for ADUs. Where can I find them? on Facebook Share We're now 12 days past the implementation deadline and I don't see anything about Renton's new regulations for ADUs. Where can I find them? on Twitter Share We're now 12 days past the implementation deadline and I don't see anything about Renton's new regulations for ADUs. Where can I find them? on Linkedin Email We're now 12 days past the implementation deadline and I don't see anything about Renton's new regulations for ADUs. Where can I find them? link

    We're now 12 days past the implementation deadline and I don't see anything about Renton's new regulations for ADUs. Where can I find them?

    GregL65 asked about 2 months ago

    Hi there! The adopted ordinance is available online. The ordinance document shows all code amendments; unless it is a new or relocated code section, new text will be underlined and deleted text is shown with strikethrough. For additional resources and information please see RentonWA.gov/housingleg. 

    Please note the changes are not yet reflected in Renton Municipal Code. After new code amendments are adopted and in effect, it typically takes 3-4 weeks for the codifier/CodePublishing staff to update and codify the changes, but it may vary depending on the complexity of the code amendments and current workload. In the meantime, refer to the linked ordinance


  • Share When does law take effect on Facebook Share When does law take effect on Twitter Share When does law take effect on Linkedin Email When does law take effect link

    When does law take effect

    Sweetscottyt asked 4 months ago

    Hi, Scotty! The new regulations for ADUs and middle housing are scheduled to take effect June 30, 2025. 

  • Share Has the city finalized zoning regulations in compliance with the House Bill? If so where can we read new zoning. If not, do you know when? Thank you on Facebook Share Has the city finalized zoning regulations in compliance with the House Bill? If so where can we read new zoning. If not, do you know when? Thank you on Twitter Share Has the city finalized zoning regulations in compliance with the House Bill? If so where can we read new zoning. If not, do you know when? Thank you on Linkedin Email Has the city finalized zoning regulations in compliance with the House Bill? If so where can we read new zoning. If not, do you know when? Thank you link

    Has the city finalized zoning regulations in compliance with the House Bill? If so where can we read new zoning. If not, do you know when? Thank you

    Steve asked 3 months ago

    Hi, Steve! The draft ordinance will go to City Council for first reading on June 16, and then second reading on June 23, with an anticipated effective date of June 30. Feel free to send me an email (it was not included with your inquiry) and I'd be happy to share the materials.

  • Share I am planning to build an ADU per new state regulations as of 7/1/2025. Has the City of Renton developed any guidelines/code for what can be built. e.g. can it be build larger then my existing house at 1414 N. 32nd? Does it have to have the same appearance as my existing home? What will be the minimum set backs to property lines and other structures? Provide any details that you can at this point in time. Thank you, Mark Yormark on Facebook Share I am planning to build an ADU per new state regulations as of 7/1/2025. Has the City of Renton developed any guidelines/code for what can be built. e.g. can it be build larger then my existing house at 1414 N. 32nd? Does it have to have the same appearance as my existing home? What will be the minimum set backs to property lines and other structures? Provide any details that you can at this point in time. Thank you, Mark Yormark on Twitter Share I am planning to build an ADU per new state regulations as of 7/1/2025. Has the City of Renton developed any guidelines/code for what can be built. e.g. can it be build larger then my existing house at 1414 N. 32nd? Does it have to have the same appearance as my existing home? What will be the minimum set backs to property lines and other structures? Provide any details that you can at this point in time. Thank you, Mark Yormark on Linkedin Email I am planning to build an ADU per new state regulations as of 7/1/2025. Has the City of Renton developed any guidelines/code for what can be built. e.g. can it be build larger then my existing house at 1414 N. 32nd? Does it have to have the same appearance as my existing home? What will be the minimum set backs to property lines and other structures? Provide any details that you can at this point in time. Thank you, Mark Yormark link

    I am planning to build an ADU per new state regulations as of 7/1/2025. Has the City of Renton developed any guidelines/code for what can be built. e.g. can it be build larger then my existing house at 1414 N. 32nd? Does it have to have the same appearance as my existing home? What will be the minimum set backs to property lines and other structures? Provide any details that you can at this point in time. Thank you, Mark Yormark

    markyormark asked 8 months ago

    Hi, Mark –

    Thank you for your inquiry! 

    Staff continues working on drafting the required amendments for compliance with the state mandates, so nothing concrete to share for now. However, we are not proposing to increase maximum ADU size from 1,000 sq. ft., so you would not be allowed to construct an ADU that is larger than the existing residence. Feasibility and ADU size will depend upon ability to meet development standards (e.g., setbacks, impervious surface coverage, height, etc.). Existing standards can be found in RMC 4-2-110A, RMC 4-2-110C, and RMC 4-2-116.

  • Share Are adu sq ft floor space increasing on July 1st in rural King County on Facebook Share Are adu sq ft floor space increasing on July 1st in rural King County on Twitter Share Are adu sq ft floor space increasing on July 1st in rural King County on Linkedin Email Are adu sq ft floor space increasing on July 1st in rural King County link

    Are adu sq ft floor space increasing on July 1st in rural King County

    Rick asked 5 months ago

    The City of Renton is not increasing maximum building area for ADUs and the maximum ADU size will continue to be 1,000 sq. ft. However, all permitting and land use questions will need to go through King County. See the following contact information and question form for the King County Permitting Division:

    Department of Local Services, Permitting Division
    919 SW Grady Way, Suite 300
    Renton, WA  98057

    Ask them a question Fill out their form to get a response

    Customer service: call 206-296-6600 during the following hours: 9-11 a.m. and 12:30-2:30 p.m., Monday, Tuesday, Thursday, Friday.

Page last updated: 14 Jul 2025, 03:29 PM