ADU permit process overview
ADU permit threads describe a path of feasibility, plans, submittal, review, corrections, approval, and inspection milestones — not a single approval date promised upfront.
Permit timelines vary widely by city and county workload. Homeowners on ADU forums report multiple review cycles when energy code, fire separation, or utility details need clarification. Budget time for corrections, not just first submittal.
Design documents typically include site plan, floor plan, elevations, structural details where required, and energy compliance forms. Owner authorization is required for application submission even when a contractor handles the paperwork.
Inspection milestones during construction — foundation, framing, MEP rough-in, insulation, final — gate each next phase. Work ahead of approval or inspection is a common source of tear-out and redo.
Keep a single folder of approved plans, permit card, and inspection sign-offs. When you sell the property or refinance, lenders and buyers often ask for that paper trail.
Permit path (overview)
- Feasibility Zoning, setbacks, utility path confirmed for your address.
- Design documents Plans, elevations, structural and energy details as required.
- Application submittal Forms, fees, and plans to the building department.
- Plan review Corrections and resubmittals until code compliance is met.
- Permit issuance Approved permit before foundation and framing work.
- Inspections Foundation through final; each passed inspection unlocks the next scope.
Documents often required
- Site plan with setbacks and utility locations
- Floor plan and elevations
- Structural calculations when required
- Energy code compliance documentation
- Owner authorization for application
- Fire separation details between ADU and main dwelling when applicable
If your lot is in a historic district or HOA-controlled community, add design review time to the calendar. Those layers run parallel to building department review and can require separate submittals.
