Accessory Dwelling Units (ADU's)

What is an Accessory Dwelling Unit (ADU) and a Junior Accessory Dwelling Unit (JADU)?

An ADU, also known as a Second Unit, In-Law Unit, or Granny Unit, is an accessory dwelling unit with complete independent living facilities for one or more persons.  

On January 1, 2020, new State law took effect to create opportunities for accessory dwelling units (ADUs) and junior accessory dwelling units (JADUs) at single-family dwellings (CA Gov’t Code section 65852.2). Beyond traditional market rate construction and affordable housing developments, ADUs provide an alternative, flexible housing model that can help address home supply and affordability in California.

  • Detached: The unit is separated from the primary structure.
  • Attached: The unit is attached to the primary structure.
  • Converted Existing Space: Space (e.g., master bedroom, attached garage, storage area, or similar use, or an accessory structure) on the lot of the primary residence that is converted into an independent living unit.
  • Junior Accessory Dwelling Unit (JADU): A specific type of conversion of existing space that is contained entirely within an existing or proposed single-family residence.

ADUs and JADUs are separate from the recently adopted State law known as SB 9 (CA Gov’t Code section 65852.21), effective January 1, 2022. In some situation, but not all, it may be possible to have two principal units through SB 9, as well as an ADU/JADU. Learn more about building housing units and lot splits through SB-9.  

Examples of ADU Types:


What is the permitting process for constructing an ADU and/or JADU?

The ADU approval is “ministerial” or administrative. The first step in the permitting process is to refer to the Town’s ADU Regulations Section 10-6.103 to determine whether the ADU is exempt from an ADU Permit (ministerial Building Permit review only) or if an ADU Permit (administrative Planning Department approval) is required.  

Please review the Planning ADU/JADU Information Handout for helpful information regarding the zoning requirements for ADUs and JADUs.  

If you have determined that your project is exempt from an ADU Permit, then you may apply directly to the Building Department for a Building Permit.  Building Permits are only accepted online through the Town’s Permit Center. 

If you have determined that your project will require an administrative ADU Permit, then you will need to apply to the Town’s Planning Department.  All Planning land use approvals and permit applications are only accepted online through the Project Portal.

You may also submit simultaneously to both the Planning Department and Building Department, however, the Planning Project must be approved prior to any building permit being issued.

What funding is available to assist homeowners in building an ADU?

Although there is currently not funding available from the Town of San Anselmo to assist homeowners in constructing an ADU, there are other resources that homeowners may review for funding assistance. The California Department of Housing and Community Development has an ADU webpage that includes a section of ADU Funding for Homeowners that the State updates.

One example is the CalHFA’s ADU Grant Program, effective on or after September 20, 2021, the CalHFA ADU Grant Program will provide up to $25,000 in assistance to reimburse homeowners for predevelopment costs necessary to build and occupy an ADU.

ADU and JADU Resources:

Ordinance No. 1172
Title 10, Chapter 6, Accessory Dwelling Units
ADU/JADU Submittal Application Checklist
ADU/JADU Information Handout
ADU Wall Height Measurement

ADU Workbook

ADU Deed Restriction Form

JADU Deed Restriction Form

More Information:

For further inquiries regarding the Planning Division’s permit process, please email:
For further inquiries regarding the Building Division’s permit process, please email:
Refer to the eTRAKiT Portal for assistance on submitting your application online.