ADU permit process in Millbrae, California
Last verified August 29, 2026
Prepared by GetYourPermit editorial teamReport an error
This guide includes the portions of the City permit process that passed our evidence review. Confirm project-specific requirements with the City before submitting.
Where to apply
- Department
- Building Division
- Permit portal
- City Online Portal System
Step by step
- 1
Review City ADU reference materials and consult Planning or Building
Review City ADU page and official reference links Contact Planning about ADU requirements or Building Division about submittal requirements City guidance and a defined electronic submittal route
- 2
Submit electronic Building Permit application and required documents
Register a portal account Complete City information, scope, application and submittals pages Submit required electronic documents Submitted online Building Permit application
- 3
City and pertinent departments perform electronic plan review
Pay any required plan-check fee after City accepts the application For qualifying pre-approved plans, submit City checklist materials Department comments, approvals or conditions
- 4
Correct and electronically resubmit incomplete or returned materials
Address missing documents or City concerns Resubmit through the City online portal Corrected electronic resubmittal
- 5
Satisfy City conditions and pay permit fees for issuance
Satisfy applicable department conditions Pay Building Permit fees at permit issuance Issued Building Permit
- 6
Request City inspections before advancing work
Request inspection at least one day in advance Ensure the proper inspection occurs before proceeding to the next work phase Required City inspection
- 7
Pass final inspection and receive Certificate of Occupancy
Complete all work and departmental conditions Pass final inspection Certificate of Occupancy
What you need to submit
- Application for Building, Electrical, Plumbing and Mechanical Permit — only in some cases
- Pre-Approval of ADU Plans - Submittal Checklist and master-plan materials
- Pre-approved ADU site-specific Building Permit materials
Pre-approved ADU plans
Use Millbrae’s official page to confirm which designs, site conditions, and supplemental documents qualify. Plan-check timing still depends on the project and city review.
View pre-approved plansProject-specific next step
Build your Millbrae permit report
Choose your ADU type and size to bring the City process, researched permit fees, and early construction budget into one planning report.
Sources for this guide
Additional city reference pages
Accessed August 28, 2026
The page's historic January 2024 single-family impact-fee amount is not treated as a current rate.
Accessed August 28, 2026
Official source for the current City fee schedule, rule, or verification path.
Accessed August 28, 2026