Building an ADU in Livermore

What you can build in Livermore

Livermore allows ADUs on any lot zoned for single-family or multifamily homes that has an existing or proposed home. That includes single-family, multifamily, mixed-use and residential planned development zones. The rules are in Chapter 11.30 of the Livermore Development Code, adopted in July 2025. The chapter says state law governs if the two conflict.

The city recognizes four ADU types: a conversion ADU made from existing space in the home or an accessory building, an attached ADU that adds onto the home, a detached ADU, and a junior ADU (JADU). On a lot with an existing home, you can build one conversion ADU, one attached or detached ADU and one JADU.

With an existing multifamily building, you can add up to eight detached ADUs (no more than the number of existing units), plus conversion ADUs in non-living space such as storage rooms or attics. Conversions are allowed at 25% of the existing units, rounded down, but at least one. With a proposed multifamily building, you can add up to two detached ADUs.

Whatever the other rules say, the city can't block a JADU plus either a conversion ADU or an 800 sq ft detached ADU with 4-foot side and rear setbacks that meets the height limits. [1]

Size, height and setbacks

Size. Every ADU must be at least 150 sq ft. A detached ADU can be up to 850 sq ft with one bedroom or fewer, or 1,000 sq ft with more than one bedroom. An attached ADU can't exceed 50% of the main home's floor area (not counting garages), but the city must always allow 850 or 1,000 sq ft. A conversion ADU has no size cap, and it can add up to 150 sq ft for an entrance.

Setbacks. New attached and detached ADUs need 4-foot side, rear and street-side setbacks. The front setback is 15 feet or the zone's setback, whichever is less. A conversion needs no extra setbacks if the existing ones meet fire and safety codes. A detached ADU must be at least 5 feet from other buildings on the lot, though it can attach to a detached garage or other accessory building. The ADU must be located behind the main home.

Height. A detached ADU can be 16 feet tall, plus 2 feet for a roof pitch that matches the main home. Within a half-mile walk of a major transit stop or high-quality transit corridor, it can be 18 feet plus 2 feet. On a lot with a multistory multifamily building, it can be 18 feet. An attached ADU can be 25 feet or the main home's height limit, whichever is lower. A conversion keeps the existing height.

Lot coverage and open space. A new attached or detached ADU, the home and an attached garage together must fit the zone's lot coverage and floor area limits. The ADU also needs a private open space of at least 10 by 10 feet next to it.

Design. Every ADU needs its own outside entrance. A detached ADU's entrance can't face the street, and an attached or conversion ADU's entrance can't be on the front of the home. New stairways must be enclosed. Balconies, roof decks and decks more than 2 feet above grade are not allowed. A new attached or detached ADU must match the main home's roof material, siding and color. On properties listed as "Significant" or "Potentially Significant" historic resources, attached ADUs are not allowed. [1]

Parking

A new attached or detached ADU needs one off-street parking space, on top of the main home's parking. It can be tandem with other ADU spaces but shouldn't block the home's required parking. No space is needed for a conversion ADU or JADU, or within a half-mile walk of public transit, which Livermore says includes local bus stops and the ACE train. Other exemptions cover historic districts and listed historic homes, areas where on-street permits are required but not offered to the ADU's occupant, and lots within one block of a car share space.

If you demolish or convert a garage, carport or parking space to build an ADU or JADU, you don't have to replace it.

State law, as HCD explains it, goes further: cities "may not impose parking requirements on 66323 Units," which include a new detached ADU of up to 800 sq ft with 4-foot side and rear setbacks. HCD also lists an exemption for an ADU applied for together with a new home. Livermore's code doesn't list these, so confirm with the Planning Division before you plan a parking space. [1][4]

Fees and utilities

Livermore charges no impact fee on an ADU under 750 sq ft or on any JADU. For an ADU of 750 sq ft or more, impact fees are charged in proportion to the main home's size. State law, as HCD explains it, exempts ADUs of "750 square feet of interior livable space or less," so if your ADU is exactly 750 sq ft, ask the city how it will be charged. HCD's handbook also says school districts may charge fees on ADUs over 500 sq ft.

With a pre-approved plan, you pay the city a flat $1,000 plan review fee, plus construction and inspection fees. Plan check fees are due when you resubmit, and the rest when your permit is approved.

Livermore's code requires all ADU utilities (water, sewer and power) to connect through the main home. Separate ADU utility connections are not allowed. If the main home has gas, the ADU can have gas too; if not, the ADU can't. New detached ADUs generally need solar panels under the state energy code. For typical costs, see our ADU cost guide. [1][2][3][4]

How long it takes

Livermore's code says a complete application will be processed within 60 days unless you ask for a delay. If the city doesn't act in time, the application is deemed approved. With a plan the city has pre-approved in the current building code cycle, the code sets a 30-day deadline. The pre-approved plan page says those applications are reviewed in 7 business days, compared with 15 for standard applications.

The city's permit review times page lists about 25 days for a first ADU plan check, not counting weekends or holidays. All review times depend on workload. If you apply for an ADU with a new home, the ADU is processed after the home. See our ADU permit process guide. [1][3][5][6]

Garage conversions and junior ADUs

A garage can become a conversion ADU, with no size cap and no replacement parking. A detached ADU can also be attached to a detached garage that meets the city's accessory structure rules. See our garage conversion guide.

A junior ADU (JADU) is 150 to 500 sq ft and must be entirely inside an existing or proposed home, which can include an attached, enclosed garage. It needs an efficiency kitchen with a sink, cooking appliances, refrigerator, counter and cabinets. It can share a bathroom with the home; if it does, it must have an inside door to the home. Its outside entrance can't be on the front of the home. It shares utilities with the home and gets no separate meter or address. You record a deed restriction with the Alameda County Recorder before the final inspection.

Livermore's code requires the owner to live in the home or the JADU in every case. State law has changed: HCD's handbook says owner occupancy is required only when the JADU shares a bathroom with the main home. If your JADU has its own bathroom, confirm with the Planning Division. [1][4]

Renting and selling an ADU

You don't have to live on the property to build or rent an ADU. ADUs and JADUs can't be rented for less than 30 days. An ADU can't be sold separately from the main home, except under Gov. Code 66341. An ADU can't get a certificate of occupancy before the main home does.

The city won't deny an ADU or JADU because of nonconforming conditions, code violations or unpermitted structures on your lot that don't threaten health and safety and aren't affected by the ADU. [1]

Lot splits and duplexes (SB 9)

Livermore applies SB 9 through Chapter 11.50 of its Development Code. The chapter says no more than two units may be built on each parcel, and it counts ADUs and JADUs as units. HCD's handbook says that without a lot split, a lot can get up to two SB 9 units plus the ADUs and JADUs ADU law would otherwise allow. If you want to combine SB 9 and ADUs, ask the Planning Division. SB 9 units need 4-foot side and rear setbacks. For a lot split, you sign an affidavit that you intend to live in one of the units for at least three years. Rentals must be longer than 30 days. See our SB 9 lot split guide. [4][7]

Permit steps in Livermore

1. Check the rules and talk to Planning

   Read Chapter 11.30 or the city's ADU Submittal Packet. Contact the Planning Division at (925) 960-4450 or planning@livermoreca.gov. [3][6][9]

2. Choose a design

   Hire a designer, or contract with the designer of a plan on the city's pre-approved ADU list. Pre-approved plans still need site-specific plans, studies and engineering. [3]

3. Gather your documents

   The submittal packet lists a construction permit application, construction drawings with setbacks, photos and elevations showing the ADU matches the home, fire sprinkler plans, structural and energy calculations, a title report no more than 6 months old, the Zone 7 Impervious Surface Worksheet and the Clean Water Site Measures Declaration. [6]

4. Apply online

   All permits are online only. Create an account on the city's Accela Citizen Access portal, select "Building", then "Create Application", and upload your plans. Start from the Online Permitting page. [2][6]

5. Respond to corrections and pay fees

   Staff email you if corrections are needed. Plan check fees are due when you resubmit, and the rest when the permit is approved. The city must act on a complete application within 60 days. [1][2]

6. Record the JADU deed restriction and build

   For a JADU, submit the deed restriction with your application and record it with the Alameda County Recorder before the final inspection. Keep the permit, inspection card and approved plans on site. [1][2]

Pre-approved and sample plans

• Pre-Approved Accessory Dwelling Unit (ADU)

  Detached ADU plans the city has found to meet zoning and building codes anywhere in city limits. You contract with the plan's designer and add site-specific work; plan review is a $1,000 flat fee and takes 7 business days. [3]

Who to call

• Planning Division

  ADU rules, pre-approved plans and the ADU code (planning@livermoreca.gov)

  925-960-4450

  City Hall, 1052 South Livermore Avenue, Livermore, CA 94550

  [3][6]

• Permit Center (Building)

  Building permits and online permitting help (permitcenter@livermoreca.gov)

  925-960-4410

  [2][3]

Questions people ask