Detached ADU (DADU) Permits in City of Sammamish
A standalone backyard cottage with its own foundation, roof, and exterior. Maximum flexibility on layout; highest construction cost. HB 1337 floor: 1,000 sf gross allowed everywhere.
Drops the placement canvas on your parcel for detached adu (dadu) scope. Live setback + coverage + easement checks; packet generation when you’re ready.
Permit fees in City of Sammamish
Fee schedule not yet aggregated — check the City of Sammamish fee schedule directly.
City of Sammamish fee scheduleFull Construction Permit (Addition/Alteration) fees. Sewer capacity charges may apply (King County: ~$8k-$10k). Apply via https://mybuildingpermit.com. Apply via MyBuildingPermit.com.
Review timeline
Typical: 45–120 business days
What a DADU permit packet contains
- A1.1 — Site plan with rotated footprint, setbacks, coverage
- A2.1 — Floor plan with rooms, openings, egress
- A3.1 — Elevations (all four faces, dim strings)
- A4.1 / A4.2 — Foundation + framing plans
- A5.1 — Wall section with WSEC R-values
- A6.0 — Glazing schedule (NFRC U-factor + SHGC)
- Filled application forms (city-specific)
- Manual J energy compliance report