Woodside Accessory Dwelling Unit (ADU) Standards

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ADU Ordinance



Zones allowed

All residential and commercial zones (R-1, SR, RR, SCP-5/7.5/10, and CC)
Lot restrictions
No more than two accessory dwelling units, including accessory dwelling units in barns, are permitted on a parcel. For parcels equal to or greater than 1.0 acre in size, but less than 1.5 acres in size, a maximum of one detached and one attached accessory dwelling unit shall be permitted. For parcels less than 1.0 acre in size, no more than one accessory dwelling unit, whether attached or detached, shall be permitted. In the R-1 District, no more than one accessory dwelling unit is permitted, and detached accessory dwelling units may only be permitted if the lot area is at least 20,000 square feet.
Minimum lot size


Min / Max ADU size
None / 1,500 sf (subject to total floor area allowed for parcel)
ADU building height
Attached: 28-30 feet (depending on zoning district)
Detached: 17 feet, 11 foot exterior wall height max


Same as primary dwelling:

  • Front: 30-50 feet

  • Sides: 15-50 feet

  • Rear: 25-50 feet

Check specific zoning district requirement for specific lot requirements.

Parking requirements
One space per unit is required unless state exemptions are met (ADU is within 1⁄2 mile of transit, in existing structures, in historic districts, within one block of car share locations, or in an area with residential parking permit rules that do not allow second units to get a permit). Parking in setbacks and tandem parking are allowed.
Owner occupancy

No requirement

Sample fees from recently built projects*
ADU - 1,493 sf, detached: $20,683
Other requirements
  • ADU shall be consistent with Residential Design Guidelines.

  • ADU shall comply with Fire District and Building Department regulations and may be required to install fire sprinklers, meet Wildland Urban Interface requirements, fire hydrant, and/or provide fire truck access/turnaround. Contact Woodside Fire Protection District and Woodside Building Department for all detailed regulations.

  • Limitations to septic installation may apply. Contact Town of Woodside and San Mateo County Department of Environmental Health for specific regulations.

  • ADU shall have all utility connects prescribed by CBC/CRC.

  • ADU must comply with Zoning Districts that require increased setbacks for portions of structures that exceed 17 feet.

  • Removal of Significant Trees as defined by the Municipal Code requires Town review and approvals of a Tree Destruction Permit.

  • Conversion of existing historical structures is encouraged by the Town if the project complies with all applicable Zoning and Building Codes, and the California Secretary of Interior Standards for Historical Resources.

  • ADUs must conform to all development standards in the zoning district in which they are proposed.


Only a building permit is required for an ADU. Staff completes design review with the building permit submittal based on the Town's Design Evaluation Criteria in the Municipal Code and the Residential Design Guidelines. Making an appointment to meet with a planner in the initial stages of the project can help avoid challenges and is highly recommended.



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