ADU Permits in City of Seattle
Verified rules for detached (DADU), attached (AADU), and junior (JADU) accessory dwelling units in City of Seattle, King County. HB 1337 conformant.
Free lookup. We’ll resolve your zoning, setbacks, and which ADU types are allowed on your specific parcel.
Choose an ADU type for your parcel
All three are permitted in City of Seattle under HB 1337. Pick the one that fits your goals and lot constraints; the per-parcel canvas verifies it against your specific zoning.
DADU — Detached
Backyard cottage with its own foundation and roof. Most flexibility on layout.
AADU — Attached
Basement, garage, or addition conversion inside the primary residence footprint.
Standard Plan (Expedited)
Pre-approved DADU plans cut review from 6–9 weeks to ~3–4 weeks. Seattle only.
City of Seattle permit-process facts
ADU permit fees
Fee schedule not yet aggregated. Check the City of Seattle fee schedule directly.
Fee scheduleReview timeline
Typical: 14–84 business days
Standard-plan DADUs cut this in half.
HB 1337 conformance
City of Seattle permits at least two ADUs per single-family lot, with no owner-occupancy requirement and parking limits that respect the HB 1337 ceilings.
Rules above are aggregated from City of Seattle’s permit-rules table; per-parcel facts (your specific setbacks, easements, ECA buffers) are pulled live on the parcel page. Primary source: https://www.seattle.gov/sdci/permits/common-projects/accessory-dwelling-units. Last verified 2026-05-25.