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Junior/Accessory Dwelling Units

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Junior/Accessory Dwelling Units (JADU/ADU)

Frequently Asked Questions

The city has prepared a list of commonly asked questions for new Accessory Dwelling Units (ADUs) and Junior Accessory Dwelling Units (JADUS), primarily related to the newly effective state of California legislation SB 13, AB 68, AB 587, AB 670, AB 671, and AB 881.

Where are ADUs allowed?

ADUs are allowed on any single-family residential, multi-family-residential and mixed-use zoned property where an existing single-family dwelling or multi-family dwelling has been established or a new single-family dwelling or multi-family dwelling is being proposed. The zoning districts which allow ADUs are R-1, R-2, R-3, R-4, P-D where residential use is allowed and Specific Plan areas where residential use is allowed. An Accessory Dwelling Unit is different from an Accessory Building.  An Accessory Building, or structure, includes sheds, tool sheds, workshops, and garden sheds. SBMC 12.84.140.

What is a Junior ADU and is it allowed?

A Junior ADU (JADU) is permitted under Government Code Section 65852.22. A JADU is a type of an ADU which is converted from an existing living area and located entirely within the existing residence.  The maximum size of a JADU shall not exceed 500 s.f. A JADU shall have an efficiency kitchen while the bathroom can be independent or can be shared with the primary dwelling.  A JADU is allowed in addition to a detached, new construction ADU in all zoning districts allowed for ADUs. A JADU requires owner occupancy of the primary dwelling.

Want to apply for a permit?

In addition to submitting for a building permit, anyone who desires to construct an ADU / JADU should also submit a completed ADU Zoning Verification Review Form and Accessory Dwelling Unit Checklist with the Planning office.  Both the documents, the Zoning Verification Review Form and the ADU Checklist, can be downloaded (see bottom of the page).  Once a complete form, fees ($925) and checklist with the complete plan set is received, the Planning staff will notify the property owner or applicant within 60 days of its decision.  For any additional information, please contact the Planning office at 650-616-7074.  The ADU Zoning Verification Review process is outlined in the flowchart above.

How many ADUs are allowed on my property?

Each single-family residential property is allowed one detached new construction ADU in addition to a JADU.  Each multi-family residential property is allowed up to two detached ADU units plus multiple converted ADUs, up to 25% of existing units that are created within any existing non-livable spaces (storage, equipment rooms, basement or passageways).

What are the new maximum unit sizes allowed under state law?

ADU statute limits the size of an attached ADU to 50% of the size of the existing primary dwelling (Gov. Code Section 65852.2(a)(1)(D)(iv)). The local agency is generally required to allow an ADU of at least 850 sq. ft., or 1000 sq. ft. if it contains more than one bedroom. In a situation where the local agency’s development standards, as noted in an adopted ADU ordinance, constrain the area for an ADU, it could be limited to no less than 800 sq.ft. (Gov. Code Section 65852.2(c)(2)(B) & (C)).

 What are the new setback requirements under state law?

There are no setback requirements for any converted ADUs.  For newly created ADUs, they must comply with the front setback requirement of the underlying zoning district and four feet minimum side and rear setbacks.

What is the new parking requirement for ADU’s under state law?

One additional parking space is required for each ADU unless it is within a half-mile walking distance from public transit, located within the architecturally and historically significant historic district, part of proposed or existing primary residence or an accessory structure, when on-street parking permits are required but not offered to the occupant of an ADU and when car share vehicles is located with one block of the ADU.  Tandem parking is allowed.  There is no replacement parking requirement for any ADU that is converted from an existing parking structure (garage or carport).

What is the new owner-occupancy requirement under state law?

Until January 1, 2025, there is no owner occupancy deed restriction requirement imposed on any ADU.  However, owner occupancy of the primary dwelling is required for any new JADU.

Is ADU subject to Development Impact Fees under state law?

Development Impact Fees are not required for any new ADUs up to 750 s.f. in size.  For ADUs that are more than 750 s.f. in size, impact fees shall be calculated proportionally to the floor area of the main house.  Connection and capacity fees should also be charged for detached ADUs only and should be calculated in proportion to the size of the unit or the total number of fixtures.  ADU can only be considered a new residential use for the new utility service fee if it is constructed in conjunction with a new primary dwelling unit.

What if I have an existing ADU that was constructed without the benefit of permits?

Until January 1, 2030, any code enforcement related correction pertaining to the creation of an ADU can be delayed up to five years, based on the owner’s request, for any ADU that was built before January 1, 2020.

Ready to apply? Check out these documents and resources for J/ADUs

California Department of Housing and Community Development (HCD) Technical Assistance Memo

City of San Bruno ADU Zoning Verification Review Form and Checklist

City of San Bruno - Find your zoning

City of San Bruno Online Application Process

Questions and Appointments

For any questions and to set up intake appointments for ADUs and JADUs please contact the City's designated ADU specialist: Rucha Dande, Associate Planner,