How long does City of Seattle take to review a ADU / DADU permit?

Typical review window: 14–84 days. Expedited review is available on request.

Which cities is the Kolmo permit lookup verified for?

Ten cities: Seattle, Bellevue, Kirkland, Redmond, Sammamish, Issaquah, Renton, Kent, Federal Way, and Mercer Island. For these, every fee, threshold, and timeline is sourced from the city directly with the exact quote and URL, and re-verified weekly. Outside these ten cities address lookup still works and we render the parcel and Washington-state baseline code, but per-city specifics are flagged as unverified.

Does the lookup cover unincorporated King, Pierce, or Snohomish County?

Address lookup works and parcels resolve to the county building department, but unincorporated coverage is currently baseline-only — Washington-state IRC, IBC, and WSEC plus state critical-area rules. Per-county fee and code deviations have not been verified to the same standard as the ten verified cities.

Will this replace calling the permit center?

For most homeowner projects — decks, kitchens, bathrooms, ADUs, fences, siding, windows, flooring, roofing, HVAC, electrical, plumbing — the published answer matches what the permit center will say, and the homeowner can submit with a pre-filled application packet. For variances, conditional uses, or unusual scope, calling the city planner is still recommended.

Where does the address go after submission?

The address is geocoded via Google Maps to identify the correct county, then queried against public county GIS endpoints. Parcel data is cached for 30 days. The address is not contacted, sold, or shared with third parties.

Who built this — and why?

Built by Kolmo Construction, a licensed Seattle-area general contractor. The team works with permit code daily and built this to fix the public web's poor coverage of homeowner permit questions. The lookup is free; if a homeowner wants a contractor for the project, Kolmo is one option.

ADU / DADU permits in City of Seattle: fees, timeline & requirements (2026)

Everything you need to know about pulling a ADU / DADU permit in City of Seattle, Washington — when one is required, what it costs, how long review takes, what documents are required, and which inspections you can expect. Cited to Seattle Department of Construction & Inspections (SDCI).

Permit required?

Yes — see threshold below

Permit fee

Construction Permit (Addition/Alteration). Pay 75% of plan-review + permit fees at application acceptance. See 2026 Fee Estimator + Director's Rule 5-2025. Pre-approved DADU plans waive most plan-review fees.

Review timeline

14–84 days · expedite available

When does a ADU / DADU need a permit in City of Seattle?

Max 2 ADUs per property (Seattle code). Pre-approved DADU plans via ADUniverse cut review to 2-6 weeks. Custom designs follow standard plan submittal (SDCI Tips 103 + 106). Owner-occupancy covenant currently required.

Required submittals

full architectural plans (Tips 103/106)
structural calcs
WSEC compliance form
site plan w/ setbacks
King County sewer capacity certification

Inspection sequence

footing
foundation
framing
rough-in (electrical/plumbing/mechanical)
insulation
drywall
final

Contractor specialties needed

general, electrical-01-or-02, plumbing, mechanical

Notes & caveats

Attached/detached ADU and DADU: Construction Permit - Addition or Alteration. Legalizing existing unit: Construction Permit Establishing Use. King County sewage treatment capacity charges apply. Parking, street improvements, and MHA do NOT apply to ADUs.

How to apply

1. Confirm your parcel's zoning & overlays. Run an address lookup on the main permits page — we'll pull your specific lot polygon, zoning, setbacks, and any shoreline/ECA/historic overlays.
2. Assemble submittals (5).
3. Submit through the city portal: Seattle Department of Construction & Inspections (SDCI) ↗
4. Track review (typical: 14–84 days). Respond to reviewer comments promptly.
5. Pay issuance fees (Construction Permit (Addition/Alteration). Pay 75% of plan-review + permit fees at application acceptance. See 2026 Fee Estimator + Director's Rule 5-2025. Pre-approved DADU plans waive most plan-review fees.) and pick up the permit. Inspection card travels with the job.

Compare this against other cities

Side-by-side ADU / DADU requirements across all 10 verified Seattle-area cities.

All City of Seattle permits

Every project type — ADU, addition, kitchen, bath, deck, fence, and more — for City of Seattle.

City of Seattle resourcesPermit portal ↗Fee schedule ↗