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Junior/Accessory Dwelling Units - UPDATED!

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Junior/Accessory Dwelling Units (JADU/ADU)

New San Bruno ADU Ordinance - April 2021

The San Bruno City Council passed a new ADU Ordinance which went into effect on April 9, 2021. As part of the City’s efforts to streamline ADU construction, there is no longer a separate Planning entitlement (zoning verification review) at the beginning of the process. All ADUs will go directly to the Building Division for a building permit submittal, where all departments will review after intake. Please contact the Building Division at (650) 616-7074 for any questions regarding building permit submittal and fees.

Designing Your ADU

The following documents will help you as you design your ADU:

Ready to Apply? Follow these steps...

The following steps with assist you in applying for a building permit with the City of San Bruno Building Division. To proceed with the building permit process, please follow the steps below:

  • Complete and submit the building permit application  and ADU submittal checklist
  • Upload the completed application, checklist, and all required materials to this link.
  • The filename should include the project address along with the words, “Permit Application”. For example, “567 El Camino Real ADU Permit Application”
  • If your project includes construction drawings and documents, please upload it with the building permit application to the link specified above. 

    Once the permit application is uploaded, please send an email to  If you do not get a confirmation from them in a couple days, please send another email requesting confirmation.

     When they have processed the permit application, they will respond to your email with the next steps which includes the following:

  • Instructions to pay any plan review fees that may apply to the project.
  • Routing of the project to plan review agencies. Please note, the plan review process will not commence unless plan review fees are paid.

If you have other questions about the building permit process, feel free to call the Building Division at (650) 616-7074.

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.

How many ADUs are allowed on my property?

Each single-family residential property is allowed one 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.