ADU Resources
Supporting you throughout your ADU journey

key resources for your adu project

Looking for advice?
If your community is a member of the San Mateo County ADU Resource Center, you can contact our staff for advice on your project. Check the Contact page for more details.

ADU Guidebook
A step-by-step guide to building an ADU in San Mateo County

Process At-A-Glance
A two-page overview of the entire ADU process.

ADU Calculator
Estimate potential costs, fees, and rents, and see how choices can impact your budget.
Pre-Designed Plans
ADU plans you can use or purchase, and some that are locally pre-approved.

Local ADU rules
An overview of ADU rules in your location.

ADU Stories
Spotlights on real ADUs built by homeowners in San Mateo County and across California.