ADUs Decisions in San Mateo County

An Accessory Dwelling Unit (ADU) is a secondary housing unit located on the same parcel as a primary single-family residence. ADUs go by many names - granny flats, in-law suites, backyard cottages, garage apartments, or casitas - but they all share the common characteristic of being smaller, subordinate residential units that share a lot with the main house. ZoneWire tracks adus activity across San Mateo County, CA public meetings.

ZoneWire monitors San Mateo County, CA planning and council meetings, transcribes them, and flags adus activity. As of the latest update we have analyzed 3 meetings and detected 8 adus mentions.

Tracking adus in San Mateo County surfaces zoning and development signals early, so developers, investors, and brokers can evaluate parcels and approvals before they reach the broader market.

The County of San Mateo Planning and Building Department administers zoning and land-use regulations throughout the unincorporated area. The Planning Commission is authorized by County ordinance to review the County General Plan and development regulations and make recommendations on their adoption or amendment to the Board of Supervisors, and it also reviews and acts upon development permits in unincorporated county areas. Zoning within incorporated cities is handled by those cities, not the County.

On October 8, 2024, the Board of Supervisors adopted an ordinance that repeals Division VI (Planning and Subdivision Regulations), Division VII (Building Regulations), and Division VIII (Natural Resources Protection) of the San Mateo County Ordinance Code and replaces those provisions with Title 8 (Development Code), Title 9 (Subdivision Regulations), and Title 10 (Building Regulations). The reorganization folds planning and building rules into the County Ordinance Code hosted and maintained by Municode.

Planning Commission hearings are generally held on the second and fourth Wednesdays of each month at 9:00 AM in the Board Chambers located at 500 County Center, Redwood City, CA 94063. Times and location can change and are indicated on the posted agenda. Agendas, staff report packets, and minutes are published on the County's Planning and Building pages.

Use the County's Planning and Building Map Viewer (GIS) and search by the 9-digit Assessor's Parcel Number (APN), since the database may not reliably locate property-specific information by street address. Expanding the Land Use layer and clicking the parcel displays its Zoning District and Zone Description, along with information on service/utility districts, flood, fire, and airport hazard areas, scenic corridors, and prime agricultural land. For help you can contact the Planning Counter at (650) 363-1825 or plngbldg@smcgov.org.

Yes. All development in the County's Coastal Zone requires either a Coastal Development Permit (CDP) or an exemption, and any permit must comply with the policies of the Local Coastal Program (LCP) and its implementing ordinances. CDPs are processed by the County at either the staff level (when a project is not within the Coastal Commission Appeals Jurisdiction) or the hearing level (for example, when a project is in the appeals jurisdiction or involves a subdivision, Planned Agricultural Permit, or Certificate of Compliance Type B). Certain County-approved CDPs may be appealed to the California Coastal Commission.

Yes. ZoneWire Free sends New Meeting Alerts for San Mateo County at no cost, with the agenda for each meeting. ZoneWire Pro adds full transcripts, zoning and development analysis, and keyword alerts for $129 per market per month.