6–10 weeks
Typical DCI review timeline
Standard Permit
Standard Building Permit for ADUs
(206) 684-8850
Seattle DCI
The Seattle ADU Permit Process
Standard Building Permit (Most ADU Projects)
Seattle uses a single Standard Building Permit for ADU construction — no tiered land use permit classification is required. Both DADUs (SMC 23.44.041) and AADUs (SMC 23.44.025) follow this process. No neighbor notification or public hearing required for standard ADUs. Learn more about Seattle's ADU ordinance (SMC 23.44.041).
Use for: DADUs and AADUs within standard Seattle zoning parameters
Shoreline Conditional Use Permit (SMA Properties Only)
Properties within 200 feet of Lake Washington, Lake Union, Green Lake, or Puget Sound fall under the Shoreline Management Act. An additional Shoreline Conditional Use Permit is required — this adds 4–8 weeks and $5,000–$15,000 in costs. ADUs can still be built in SMA areas with proper permits.
Use for: Properties in SMA zones only (confirm early in feasibility)
Standard Permit Process: Step by Step
Pre-Application Research
1–2 weeks- Verify zoning district and ADU eligibility for your parcel (DADU: SMC 23.44.041, AADU: SMC 23.44.025)
- Check for Shoreline Management Act (SMA) overlay — properties within 200 ft of Lake Washington, Lake Union, Green Lake, or Puget Sound require extra review
- Review critical areas, steep slope overlays, and setback requirements
- Confirm utility capacity (SPU sewer/water, Seattle City Light electrical)
- Check transit proximity — within ½ mile of Link Light Rail or RapidRide eliminates off-street parking requirement
Pro tip: Our GIS feasibility study checks SMA proximity, critical areas, setbacks, transit proximity, and zoning automatically. Start with your free report instead of navigating the Seattle Services Portal manually.
Design & Documentation
2–4 weeks- Hire an architect experienced in Seattle ADU projects
- Prepare site plan showing ADU placement, setbacks, and access
- Create floor plans and elevations
- Prepare stormwater/drainage plan
- Complete energy code calculations (WA Energy Code 2021)
- Get a boundary or site survey if needed
Pro tip: Seattle DCI reviewers have specific expectations for ADU submittals. Working with a designer who has done Seattle projects before reduces correction letters significantly.
Submit Application
1 day- Submit online permit application via Seattle Services Portal (aca.seattle.gov)
- Upload all required drawings and documentation
- Consider submitting to ADU Pre-Screening first for informal feedback
- Pay application fees online
Pro tip: Submit a complete package the first time. Incomplete applications are the #1 cause of delays — DCI will place your application on hold until all documents are received.
DCI Review
6–10 weeks- Seattle DCI performs combined plan review (zoning, structural, electrical, plumbing)
- Seattle Public Utilities reviews stormwater/drainage
- May receive correction letters — respond promptly
- SMA properties: Shoreline review adds 4–8 additional weeks
Pro tip: Stay responsive. When DCI sends corrections, address them within days, not weeks. Your application moves to the back of the queue if it sits.
Permit Issued
—- Standard Building Permit issued — construction can begin
- Post permit on-site as required by SMC
- Schedule required inspections as construction progresses
- Final inspection for Certificate of Occupancy
Pro tip: Your contractor must be familiar with Seattle DCI inspection scheduling. We coordinate all inspections as part of our build process.
Before you start the permit process: Get a free feasibility study to confirm your property's zoning, setbacks, SMA proximity, and critical areas. This saves you from investing in design work before knowing what constraints apply. Already know you qualify? See our full cost breakdown to budget the complete project.
Required Documents Checklist
Tips for Faster Approval
Use the Seattle Services Portal (aca.seattle.gov) to track your application status in real time — you'll see when it moves to each reviewer.
Consider the ADU Pre-Screening route for informal DCI feedback before formal submittal. It can surface issues without burning permit review time.
Submit during off-peak months (January–March) when DCI reviewers are less backlogged.
Respond to correction letters within 3 business days to keep your application at the top of the queue.
If your property is near a shoreline (Lake Washington, Lake Union, Green Lake, Puget Sound), confirm SMA applicability early — it adds 4–8 weeks and $5,000–$15,000 in additional costs. It does NOT prohibit ADU construction.
Our Full Permit Package handles all DCI coordination, portal submissions, and correction responses. See our contact page to learn more.
Seattle Department of Construction & Inspections (DCI)
Phone: (206) 684-8850
Portal: aca.seattle.gov
DCI home: sdci.seattle.gov
Permit info: seattle.gov/sdci
Last updated: June 2026. Not legal advice. Verify current requirements with Seattle DCI.
Let Us Handle the Permitting
Our Full Permit Package covers all zoning verification, documentation, and DCI coordination. Your investment is applied as a build deposit.
Start Your Permit PackagePrefer to call? (206) 222-2898
