What's the fastest way to permit a DADU in Seattle?
✓ Verified against code · August 19, 2026
Use a pre-approved plan from the city's ADUniverse gallery — SDCI estimates roughly 2–6 weeks for pre-approved designs versus an unpublished (longer) timeline for custom designs.
Citation: SDCI / ADUniverse
How current is this?
Seattle’s ADU rules run under SMC 23.42.022 and the new Chapter 23.44 (Neighborhood Residential) (Ordinance 127376 (CB 120993)). Seattle rewrote its residential zoning twice in eight months: the HB 1337 compliance package (Ord 127211, May 2025), then the permanent state-compliance code signed December 22, 2025 and effective January 21, 2026, which repealed the old Chapter 23.44 and amended SMC 23.42.022. Most guides written in 2025 describe interim rules that no longer exist. We verified this answer against primary sources on August 19, 2026, and every change we catch is logged in the changelog.
More Seattle ADU questions
- Does a backyard cottage count against Seattle's floor-area limits?
- How many ADUs can I build on my Seattle lot?
- Do I need to add parking for an ADU in Seattle?
- Do I have to live on the property?
- Can I sell a Seattle ADU separately from the house?
All Seattle ADU rules → · Compare Washington cities →
Not legal advice — lot-specific overlays can change the answer for your parcel. The citation above points at the governing code section; check it, or ask the city to confirm.