GetYourPermit

ADU permit process in San Mateo, 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
Contact
(650) 522-7172building.info@cityofsanmateo.org

Step by step

  1. 1

    Create CSS account and submit complete ADU/JADU application

    Create/confirm CSS account Upload complete plans, documents and project materials CSS pre-application that moves to full application after City processing

  2. 2

    City Building, Planning and conditional agency review

    Pay City-assessed application fees through CSS Receive comments and provide resubmittals through CSS For pre-approved plan, retain exact pre-approved design while adding site-specific materials Review comments or plans ready for issuance

  3. 3

    Complete pre-issuance conditions and receive permit

    Complete ADU affordability survey For JADU, record City-prepared deed restriction Pay other applicable conditions and fees as directed Permit issuance communication through CSS

  4. 4

    Construction and inspection after issued permit

    Proceed only after Building Permit issuance and follow City inspection requirements

What you need to submit

  • Complete electronic Building Permit plan package
  • Plot plan with site, utility and environmental information
  • Pre-Approved Plan Phase 2 site-specific package
  • Completed ADU Affordability Survey
  • Recorded deed restriction

Pre-approved ADU plans

Use San Mateo’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 plans

Project-specific next step

Build your San Mateo permit report

Choose your ADU type and size to bring the City process, researched permit fees, and early construction budget into one planning report.

Start my permit report

Sources for this guide

Additional city reference pages