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San Rafael ADUs

Everything about building Accessory Dwelling Units in San Rafael, CA

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The city government of San Rafael will approve ADUs under California's statewide mandated regulations.
The California Building Code (CBC) 2019 is adopted.

Last Updated 01/26/21


City Hint: The city permitted a total of 17 ADU projects in the past year of 2019, which makes it above average for ADU production compared to other cities statewide.

Number of ADUs allowed:

• Single Family
o Within an existing or proposed single-family home: One ADU or one JADU per lot if exterior access is available; and side and rear setbacks are sufficient for fire and safety.
o Detached: One detached, new construction ADU can be added to a property. This can be in addition to a JADU.
• Multifamily
o Within Existing Structure: At least one ADU within portions of existing multifamily dwelling structures that are not used as livable space if each unit complies with state building standards. The number of ADUs shall allow up to 25% of the existing multifamily dwelling units. No JADUs allowed
o Detached: Not more than two ADUs that are located on a lot that has an existing multifamily dwelling but are detached from the dwelling and are subject to a height limit of 16 feet and four-foot rear and side setbacks

Types of ADUs allowed:

Detached ADU, Attached ADU, Junior ADU are allowed. Accessory Dwelling Unit (ADU)s may be new construction or converted from existing space. JADUs must be converted from existing space.

Lot size:

Accessory Dwelling Unit projects on single family or multi-family residential properties will not be subject to the minimum lot size of the underlying local zoning code or by special ordinance. ~ According To AB68

ADU size:

There is no square footage limit for existing space. If you are adding square footage to create an ADU, the square footage of the unit cannot exceed 50% of the main residence. A detached ADU cannot exceed 1,200 square feet.


Setbacks for a detached new construction Accessory Dwelling Unit (ADU) shall be no more than 4 ft from the rear and side lot lines. No setbacks shall be required for Accessory Dwelling Unit (ADU)s and Junior Accessory Dwelling Unit (JADU)s converted from legally established existing space. Attached new construction Accessory Dwelling Unit (ADU)s and conversions from existing space to be expanded must comply with the setbacks of the underlying zone. ~ AB68 & AB881 Update

An ADU may only be placed between the front-facing wall of the primary structure and the front setback with administrative design review.


Properties which convert an existing garage to an Accessory Dwelling Unit or Junior ADU will not be subject to replacement parking requirements. ~ Updated: State Law AB-68

When ADUs are created through the conversion of a garage, carport or covered parking structure, replacement off-street parking is not required.

Fire Safety:

Fire sprinklers cannot be required in an ADU if sprinklers are not required for the primary residence. However, if the addition of the ADU incorporates a remodel of more than 50% of the main residence then sprinklers will be triggered for both the main residence and the ADU.

Shape, materials and style:

Review and approval of a discretionary Environmental and design review Permit by the Planning Commission pursuant to Chapter 14.25 will be required for any ADU proposed as follows:

An upper story addition to the main residence that exceeds 500sf
A detached ADU that is two-stories
A detached ADU located within side or rear yard setbacks required for the main structure setbacks
New construction on a lot subject to the Hillside Overlay (-H) District Development regulations; if required
for the addition per Chapter’s 14.12 and 14.25
Note: Upon application for review, the Community Development Directory may propose to downgrade review to the Zoning Administrator level, if a concurrent Use Permit is not required.

Architectural Compatibility

Prior to approval a City planner will review the design plans (and visit the project site in the case of legalizing a ADU) to ensure that the ADU incorporates the same or similar exterior colors, architectural detailing, roof pitch same or similar and exterior materials, and window style, as the structure containing the principal residence.


If the unit is added to a principal single-family dwelling, the height limit is 30 feet above grade. If a unit is proposed as an accessory structure, the height limit is 15 feet. (I.e., consistent with the underlying zoning district standards for height limits and measurement). Note that Use Permit and/or Design Review permits may be required for second units in accessory structures that exceed the height limit.

Design review:

ADUs are subject to ministerial review by the Planning Division prior to issuance of a building permit. Additional zoning entitlements may be required, as specified in San Rafael Municipal Code Section 14.16.285. A ADU review fee ($_____) and application form along with project plans (___ sets) must be submitted to the Planning Division which will verify whether the unit complies with the ADU Performance Standards. If building permit clearance is granted, a ADU deed restriction must be recorded for the property.
Review and approval of a discretionary Use Permit by the Planning Commission is required for any ADU proposed as follows:

A detached ADU that exceeds the foot height limit and/or located within side or rear yard setbacks required for the main structure
A ADU that exceeds 800 square feet in size (up 1,000 square feet )

Number of Bedrooms:

Not specified by State Standards.


Between between 2020 and 2025, owner occupancy requirements will not apply to new Accessory Dwelling Units. (applicable to new construction and conversion units) ~ SB13

Utility connections:

Local health officer approval where a private sewage disposal system is being used, if required. (State requirements)


What is a Second Dwelling Unit?

A Second Dwelling Unit (aka, “in-law” or “granny” unit) is an additional dwelling located on the same lot as a single-family residence which contains separate living/sleeping, sanitary, and cooking facilities. A second unit may be located within the principal dwelling or can be in a detached accessory building. The unit cannot be sold separately from the principal dwelling.


What are the Rules for Legal Conforming or Non-conforming Second Dwelling Units?

A an existing unit constructed and established prior to adoption of zoning regulations for second units may be protected under Section 14.16.060 (Conservation of Dwelling Units). To determine applicability, the owner must produce evidence that the unit was either legally established prior to 1950 (prior to adoption of the City’s first Zoning Code) or constructed prior to January 1, 1991. This may require submittal of documentation and a zoning determination request to the Planning Division. Typically, evidence is provided through building permit records. If such records do not exist, evidence could include documentation of the residential building record used for assessment purposes, which may be obtained from the County Assessor’s office.


The second unit must have a separate entrance from the principal dwelling. In order to maintain the appearance of a single-family residence, the entrances to the second unit and principal dwelling unit cannot be located on the same side (elevation) of the principal dwelling most parallel to the front property line.

Allowed Zones:

*** Beginning in 2020, according to state law, all residential zoning districts, including single-family and multi-family, are allowed to build Accessory Dwelling Units. ***

Kitchen / Bath:

A suitable kitchen facility must be separate from the bathroom and provide a sink, cooking facility (more than a hot plate or microwave), refrigeration and storage. A suitable bathroom facility must include a toilet, sink and bathing facilities.

Legalize Existing Unit

Can an Existing (Unpermitted) Second Unit be legalized?

Yes. The unit must meet all requirements for a second unit, and obtain planning review of a Second Dwelling Unit. Building permit fees to legalize an existing unauthorized second unit will be tripled and planning fees will be doubled.

Residential Building Code:

The California Building Code (CBC) 2019 is adopted.

San Rafael City Planning Offices

San Rafael Planning Office

Hours: 8:30 a.m. - 5:00 p.m. Monday-Friday

1400 Fifth Avenue, Top Floor San Rafael, CA 94901 San Rafael, CA 94901

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ADU Design Library

Browse hundreds of models to find the right fit for your property.

ADU Model 216 sqft

W 18 ft L 12 ft

ADU Model 160 sqft

W 16 ft L 10 ft

ADU Model 645 sqft

W 43 ft L 15 ft

Customer Reviews

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Monica H. in Oakland, CA

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Alexandria in Santa Ana, CA

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Customer Reviews

"My permits were APPROVED, thank you for all your hard work. I am in the process of meeting with contractors. "

Mary S. in San Jose, CA

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Patrick L. in Orange County, CA

Detached ADU - Completed in 2020
1,003 sq. ft., 3 bed, 2 bath

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Costs / ROI



* upon completion of ADU


* based on local average price per sqft


* estimated by location


* 30 years / 5% interest rate / 20% down payment


Size: 500 sqft


Appreciation Estimate = (Base Value: $) / (Home's Living Space: sqft) * (ADU's Living Space: sqft)

Rental Estimate = (Rent Per Sqft: $5.02) * (ADU's Living Space: sqft)

Check your property's zoning, browse designs & get contractor estimates for your ADU project:

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