Accessory Dwelling Units (ADU)

ADUWhat is an Accessory Dwelling Unit (ADU)?

An “ADU” means a building or portion of a building designed for use and occupancy by people living independently of the occupants of the main residence building and containing separate kitchen, bath, sleeping, or living  facilities. 

    Attached Accessory Dwelling Unit: means an accessory dwelling unit that is structurally attached to the main residence but which has independent, direct access from the exterior. 

    Detached Accessory Dwelling Unit: means an accessory dwelling unit that is not structurally attached to the main residence. 

There are three key types of ADUs outlined below:

o    Conversion ADU: Space within an existing or proposed home (like an attached garage or attic) or within the existing footprint of a permitted accessory structure (like a detached garage or outbuilding), can be converted into an ADU, as long as the space has side and rear setbacks sufficient for safety (per the building and fire codes) and it has its own front door, independent of the main home.  

ADU Image 1o    Attached ADU: A newly constructed unit that is connected to the primary main residence by at least one wall.

o    Detached ADU: A newly constructed unit that is freestanding or separate from the primary main residence, like a cottage, pool house, or guesthouse. 

What is an Junior Accessory Dwelling Unit (JADU)?

A “JADU” means a unit that is no more than five hundred square feet in size and contained entirely within a single-family residence. A junior accessory dwelling unit shall include an efficiency kitchen, which shall include all of the following: a cooking facility with appliances, a food preparation counter and storage cabinets that are of reasonable size in relation to the size of the junior accessory dwelling unit. A junior accessory dwelling unit may include separate sanitation facilities or may share sanitation facilities with the existing structure. 

Do you have an ADU or JADU?

If you have an ADU or JADU, please take part in our Survey!

Outside Agency Housing Resources – Renting your ADU or Finding an ADU to Rent

These organizations can help match individuals seeking housing with people who have an ADU to rent and/or can assist homeowners in renting out their ADUs or JADUs. 

  • HIP Housing Home Program
    • HIP Housing can assist Home Providers as well as Home Seekers. HIP Housing can conduct interviews virtually, in office, or at a home visit. HIP Housing can assist with client applications, conduct background searches, discuss home provider incentives, help determine rent ranges, and provide resource packets for new Providers. General Services include:
      • Provider and Tenant Interviews
      • Tenant Applications 
      • Background Searches
      • Rent Range Categorization
      • Resource Packets
      • Provider/Seeker Matching Program
        • The Town can also assist with referring Home Seekers from the local area via partnerships with Menlo College, Menlo School, Sacred Heart Schools, Stanford, and other local connections.
      • Lease Agreements
      • Conflict Resolution Resources
  • Hello Housing
  • HEART Housing of San Mateo County

Other Resources

Visit Atherton Municipal Code to learn more about ADUs and Junior ADUs in the Town of Atherton. To access additional information about ADUs in San Mateo County please visit the Second Unit Resource Center - click here

 Listing on the above list is not a representation by the Town of any particular vendor.