San Mateo County
Portola Valley ADU rules
Portola Valley has an official local rule record in this scrape. Provider research is grouped at the San Mateo County level.
Local rule facts
Min/max ADU size
External ADU: 800 to 1,500 square feet depending on proposed setbacks/FAR JADU: 500 square feet Internal ADU: 1700 square feet *Not more than 50% of primary dwelling square footage, unless 50% of primary dwelling is less than 800 square feet.
Height
Not yet parsed from an official local source.
Setbacks
less than base zoning district: 16 feet vertical/maximum height Compliant setbacks: 18 feet vertical height/24 feet maximum height *Higher builds require discretionary approval unless preempted by State Law Setbacks Less than base zoning district: Subject to additional...
Parking
JADUs/Internal ADUs: None External ADUs: One parking spot required but may be shared with primary unit on parcels 1 acre or greater. Tandem parking/parking in setbacks allowed
Owner occupancy
JADU: Required, ADU: not required for ADUs built recently (2020-2024)
Process
-at-a-Glance FAQs Floorplans Inspiration Glossary Guidebook + Exercises Pre-Designed Plans Process-at-a-Glance See the resources page Events About Contact Getting Started Learning the Rules Budgeting Design Permitting Construction Renting Getting Started Learning the...