The California ADU Permit Process: Step-by-Step Timeline for 2026

The California ADU permit process typically takes 14–21 weeks (about 3.5–5 months) from initial application to permit in hand, though it can range from 4 weeks to over a year depending on your city and how complete your plans are on first submission. State law caps plan review itself at 60 days once your application is deemed complete.

Step 1: Feasibility Review

Before drawing anything, we check property lines, utility easements, setback requirements, zoning classification, and electrical panel capacity. These details determine what you’re allowed to build and where it can go on your lot.

Step 2: Design and Plan Preparation

This is the step that matters most for your timeline. A complete, coordinated, code-compliant first submission is the single biggest factor in moving through city review quickly — incomplete plans are the most common cause of permit delays.

Step 3: Application Submission

Most San Gabriel Valley cities now accept ADU applications through an online permitting portal. We handle the submission and act as your point of contact with the building department throughout review.

Step 4: Completeness Check

As of January 1, 2026, state law (SB 543) requires the city to determine whether your application is complete within 15 business days of submission. If the city doesn’t respond in that window, your application is automatically deemed complete and the 60-day plan check clock starts.

Step 5: Plan Check and Review

This is usually the longest phase. Building, planning, zoning, fire safety, and sometimes public works departments review your plans, often simultaneously but each on their own timeline.

Step 6: Corrections and Resubmission

Almost no project is approved on the first pass. Expect one or two rounds of corrections, where reviewers flag items and we revise and resubmit. Once corrections are resolved, plans are approved and your permit is issued.

The 60-Day Rule

By law, once your application is deemed complete, the city has 60 days to act. If they don’t, your ADU application may be deemed approved. In practice, most projects move through review within that window when the initial submission is thorough — which is exactly why a strong first submission matters so much.

Let Us Handle the Permit Process for You

Potato Construction manages the entire ADU permit process for San Gabriel Valley homeowners, from feasibility review through final permit issuance. Contact us or call (626) 777-6666 for a free consultation, or learn more about our ADU services.

Frequently Asked Questions

How long does it take to get an ADU permit in California?

Most projects take 14 to 21 weeks (about 3.5 to 5 months) from application to permit in hand, though it can range from 4 weeks to over a year depending on the city and how complete your plans are.

What is SB 543 and how does it affect ADU permits in 2026?

SB 543, effective January 1, 2026, requires cities to determine if your ADU application is complete within 15 business days. If they don’t respond, the application is automatically deemed complete and the 60-day plan check clock starts.

What is the biggest cause of ADU permit delays?

Incomplete or uncoordinated plans on the first submission. A complete, code-compliant plan set the first time is the single biggest factor in avoiding multiple rounds of corrections and delays.

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