Portola Valley Accessory Dwelling Unit (ADU) Standards

INFORMATION  
Contact

Arly Cassidy, Associate Planner
650.851.1700 x 230 – This email address is being protected from spambots. You need JavaScript enabled to view it.

Website
ADU Ordinance
STANDARDS  

Zones allowed

All residential zones

Lot restrictions

None

Minimum lot size

None

Min / Max ADU size

Min: None

Max for External ADUs: 1,200 sf

Max for Internal ADUs: 1,700 sf

ADU building height

28 feet

Setbacks

Varies depending on zoning district and size of the parcel
Parking requirements
Internal ADUs: None
External ADUs: One parking spot is required but may be shared with primary unit on parcels 1 acre or greater. Tandem parking and parking in setbacks are allowed.
Owner occupancy

Owner must live in the main dwelling or the ADU. Short-term rentals are not allowed.

Sample fees from recently built projects*

ADU 1(800 sf, detached): $14,048
ADU 2 (500 sf, garage conversion): $8,839

Other requirements
  • Second Addresses allowed
  • ADUs must comply with all requirements of the underlying zoning district
  • Existing buildings and ADU(s) cannot exceed the total amount of allowable floor area or impervious surface for the parcel
  • If the primary dwelling has sprinklers, the ADU must have sprinklers
  • Single family lots with 3.5+ acres can have two ADUs, otherwise only one ADU is allowed
Process
There are three review levels:
  • Ministerial Review - up to 1,000 sf that comply with certain design requirements.
  • Staff Discretionary Review - Multiple design related issues requiring discretionary review.
  • ASCC Review - Special review needed, such as historic, second driveway or non-residential zone.

Making an appointment to meet with a planner in the initial stages of the project can help avoid challenges and is highly recommended.

Exceptions

Some parcels under 1 acre may not qualify for ADUs based on location and fire safety requirements.

Disclaimer: standards and process may vary. Consultation with the contact is recommended before starting any project.

*Fees are specific to each project and will vary. Fees change regularly. These are provided as examples only.

Download ADU Standards PDF

Updated: 12/11/2017