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Accessory Dwelling Units (ADUs) & Junior ADUs (JADU)

What is an Accessory Dwelling Unit?
An Accessory Dwelling Unit (aka, “second unit,” “in-law unit,” or “granny unit”) is an additional dwelling located on the same lot as a single-family or multi-family development. An Accessory Dwelling Unit may be attached to the primary residence, detached from the primary residence, or contained within an existing residence or accessory structure. A Junior Accessory Dwelling Unit (JADU) is a unit that is no more than 500 square feet and contained entirely within the single-family structure.

ADU Ordinance

The City of San Rafael’s ADU Ordinance establishes local regulations regarding ADUs and JADUs. The ADU ordinance makes it easier to develop an ADU and streamlines the permit review process, which further encourages and facilitates ADU construction as a source of affordable housing. The ADU Ordinance is codified in 14.16.285 – Accessory dwelling units (ADUs). On January 1, 2023, two new ADU bills—AB 2221 and SB 897—took effect that further modify the City’s adopted standards.

Regulations applying to ADUs and JADUs are as follows, with recent changes to State Law shown in italics:

Size of Unit (Floor Area).

  • ADUs would need to have a minimum 190 square feet of living area, plus bathing and kitchen facilities that meet California Building Code
  • Attached ADUs would have a maximum floor area of 1,000 square feet or 50% of the existing residence, whichever is less
  • Detached ADUs would have a maximum floor area of 1,000 square feet
  • There is no maximum size limit for ADUs that involve the conversion of an existing detached structure
  • There is no maximum size limit for an ADU created from internal conversion of portions of an existing primary residence
  • JADUs may be no less than 190 square feet of living area, plus bathing and kitchen facilities that meet California Building Code and no more than 500 square feet

Required Setbacks.

  • Maximum rear and side yard setbacks of a new or expanded ADU, either attached or detached, are 4 feet
  • No additional setbacks are required for internal conversions
  • Front yard setback will be the same as required for the primary residence, provided it does not preclude the construction of an 800 square foot ADU

Maximum Height:

  • Up to 16 feet in height for a detached ADU
  • Up to 18 feet in height for a detached ADU on a lot that is within one-half of one mile walking distance of a major transit stop or a high-quality transit corridor with an additional two feet in height to accommodate a roof pitch on that is aligned with the roof pitch of the primary dwelling unit
  • Up to 18 feet in height on a lot with an existing or proposed multi-story multifamily dwelling
  • Up to 25 feet for an ADU attached to a primary dwelling; height limited in the Eichler-Alliance overlay district to 17 feet
  • Accessory dwelling units complying with the development standards established for the primary residence are subject to the same height limit established by the district governing the property.

Additional Frequently Asked Questions

What if my property isn’t zoned residential but I have a residence on it?

The rules apply to any property that is in a zoning district that allows residential use and has either existing or proposed dwelling units. For example, the Commercial/Office zoning district (C/O) is a commercial district that allows multifamily use under certain circumstances so the rules would apply to an existing or proposed residential use in the C/O district.

Is there a minimum size for the unit?

There is a minimum size of 150 square feet. ADUs In a single-family residence: ADUs must include eating, sleeping, and bathroom facilities; a JADU may share eating and bathroom facilities with the primary dwelling provided there is an internal connection.

What is the maximum size for the unit?

If the ADU meets all development standards: 1) if you are adding square footage to create an ADU, the square footage of the unit cannot exceed 50% of the main residence or 1,000 square feet, whichever is less; 2) 1,000 square feet for a detached ADU; 3) there is no square footage limit for existing space; 4) 500 square feet for a JADU.

What if I don’t comply with lot coverage, floor area ratio, open space or similar standards?

Regardless of lot coverage, floor area ratio, natural space, front yard setback, and other standards you are allowed an ADU of up to 800 square feet provided it has the minimum 4-foot rear and side yard setback and complies with the maximum height limits.

If I demo my detached accessory structure that is less than 3 feet from the property line, can I rebuild it as an ADU? What if I just want to add on to it?

No additional setback is required for an ADU if constructed in the same location and with the same dimensions (including height) as the existing structure. An expansion of no more than 150 square feet beyond the existing dimensions can be allowed for ingress and egress purposes only.

What is the max number of ADUs and JADUs I can add to a single family house?

Properties with a single-family house may have one ADU and one JADU.

What is the max number of ADU’s and JADU’s I can add to a multi-family property?

ADUs may either be created through conversion of non-livable residential space (e.g. basement) within the multi-family structure or by conversion of existing accessory structures or new construction of detached structures. No JADUs are permitted.

  • Within Existing Main Structure:At least one (1) ADU is allowed up to a maximum of twenty-five percent (25%) of the existing multifamily dwelling units.
  • Detached:A maximum of two ADUs are allowed.

Do I need to replace parking if I convert my covered parking at my home?

When a garage, carport, or covered parking structure is demolished in conjunction with the construction of an ADU or converted to an ADU, replacement off-street parking is not required.

Do I need to provide an off-street parking space for my ADU?

One parking space is required per ADU, unless:

  • The ADU is located within one-half (½) mile walking distance of public transit
  • The ADU is located within an architecturally and historically significant district
  • The ADU is created through conversion of existing space (either in the main structure or a detached structure)
  • On-street parking permits are required but not offered to the occupant of the ADU
  • There is a car share vehicle located within one (1) block of the ADU at the time the application is filed with the
  • A permit application for an accessory dwelling unit is submitted with a permit application to create a new single-family dwelling or a new multifamily dwelling on the same lot

No parking is required for JADUs.

How can I tell if my property is within half a mile from transit?

No off-street parking is required for an ADU that is located within one-half mile walking distance of public transit.  “Public transit” means a location, including, but not limited to, a bus stop or train station, where the public may access buses, trains, subways, and other forms of transportation that charge set fares, run on fixed routes, and are available to the public.

The city has this map that shows the areas we know are within half a mile of transit. Follow this up with a snap shot of walking distance via Google Maps or other map app. If our map shows you are outside the half mile radius but you have updated information that shows you are within half a mile of transit, please submit supporting documentation to the City to review. This can be a map showing where the public transit is located and the walking path highlighted with distances located. Staff will evaluate the documents for accuracy.

Are fire sprinklers required?

Fire sprinklers cannot be required in an ADU if sprinklers are not required for the primary residence. Construction of an ADU does cannot trigger a requirement that fire sprinklers be installed in the proposed or existing primary dwelling.

How can I legalize an existing unpermitted ADU?

Unpermitted JADUs and ADUs follow the same building permit review process and California Building Code requirements as new construction, very similar to additions or remodels. Attached ADUs will need to have fire rated separations, egress, and separate electrical and mechanical systems per California Building Codes.  The application for building permits should include plans for review and payment of permit fees. Once the permit application is reviewed and issued, then inspections will need to be scheduled and final inspection passed.

What fees are charged for ADU/JADU permits and plan review?

The main fees associated with the build of your ADU/JADU include plan check fees, building permit fees, and impact fees. Most permit fees are based on the project's total cost valuation or square footage. Additional flat rate fees include electrical, plumbing, and mechanical permit fees. The following fees are waived for ADU builds less than 750 sq feet: impact fees, general plan maintenance, street maintenance, and bedroom taxes. For more information, contact Permit Services in-person on the third floor of City Hall or online at the virtual counter. Select this link to the Building Department Virtual Counter page.

My Covenants, conditions and restrictions (CC&Rs) don’t allow an accessory dwelling unit, does that override the new California laws?

CC&Rs that either effectively prohibit or unreasonably restrict the construction or use of an ADU or JADU on a lot zoned for single-family residential use are void and unenforceable.


Name Date Download
ADU Single Family Checklist March 14, 2020  PDF (250 KB)
ADU Multi-Family Checklist March 17, 2020  PDF (185 KB)


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