Tumwater is issuing fewer permits for ADUs than before. Will new rules boost construction?
The construction of Accessory Dwelling Units was increasing in Tumwater just a few years ago, with more than a dozen permitted in 2021. That number dropped to six ADUs in 2024.
The city’s General Government Committee met last week to discuss updating a service provider agreement and an interlocal agreement that ultimately would update the city’s ADU allowances to match its neighboring cities and state law.
Brad Medrud, the city’s Community Development deputy director, said two ADUs will be allowed per residential lot instead of one, as required by state law as of December 31, 2025.
The maximum size of an ADU will be increased from 800 square feet to 1,000 square feet.
Medrud said the city also will simplify its design guidelines. And Tumwater residents will be allowed to convert an existing building into an ADU even if it’s nonconforming, or no longer meets some code requirements.
He said the city’s transportation impact fees are already in alignment with state requirements for ADUs, and the city has provisions to reduce fees for ADUs that are used for permanent supportive housing.
The General Government Committee approved putting an updated service provider agreement with Artisans Group and an interlocal agreement with the cities of Olympia, Lacey and Yelm on the City Council’s consent calendar for June 17.
Tumwater first approved an interlocal agreement with the cities of Lacey and Olympia to work with Artisans Group to develop pre-approved ADU plans in 2020. Artisans Group is a Tumwater, women-led architecture firm. The new agreement makes Tumwater the lead agency in contracting for this work across all three jurisdictions, with financial reimbursement from the other cities.
The contracting work was originally under the control of the City of Lacey, according to meeting documents.
The updated interlocal agreement expands the ADU building program to include the City of Yelm.
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