Building an ADU in Berkeley, California

What you can build in Berkeley

ADUs and junior ADUs are allowed on properties with an existing or proposed single-family home. ADUs are also allowed on lots with an existing duplex or multifamily building. The city's ADU rules are in Berkeley Municipal Code (BMC) Chapter 23.306.

The city's ADU Information sheet (version 8/20/2026) sets these limits per lot:

• Single-family home, one unit on the lot: 1 conversion ADU + 1 new-construction ADU + 1 junior ADU.
• More than one single-family home on the lot: 1 ADU.
• Existing multifamily building, outside the Hillside Overlay: up to 8 new-construction ADUs, as long as the number of ADUs does not exceed the number of existing units, plus at least one interior ADU. Interior ADUs may not exceed 25% of the existing units.
• Existing multifamily building, in the Hillside Overlay: up to 8 detached ADUs on the same terms, plus at least one interior ADU up to 25% of existing units.
• Proposed multifamily building: 2 new-construction ADUs (2 detached in the Hillside Overlay).

The Hillside Overlay is an area in the Berkeley hills marked "-H" on the city's zoning map, with extra limits. You can look up your zoning on the city's Community GIS Portal.

ADUs do not count toward the density limits of your zoning district. Up to 800 square feet of ADU space is excluded from lot coverage and floor area calculations.

State law may allow more than the city's table. In a June 16, 2026 letter, the California Department of Housing and Community Development (HCD) found that Berkeley's code "fails to comply with State ADU Laws." HCD said the single-family allowance improperly limits units, and that a lot with several single-family homes "would be eligible for one converted ADU, one new construction detached ADU up to 800 square feet, and one junior accessory dwelling unit (JADU) per lot." HCD also said a lot with a multifamily building must be allowed at least one more ADU under Gov. Code 66314, and that size limits must be measured as "interior livable space" (Berkeley's table uses gross floor area). HCD gave the city until July 16, 2026 to respond. If your plan goes beyond the city's table, ask Land Use Planning how it applies these findings, and see our California ADU law page. [1][2][3]

Size, height and setbacks

Berkeley's standards for new ADUs:

• Maximum size: 1,200 square feet outside the Hillside Overlay. In the Hillside Overlay, 850 square feet for a studio or one bedroom, or 1,000 square feet for two or more bedrooms.
• Minimum size: 190 square feet.
• Height, detached: 25 feet, or 20 feet in the Hillside Overlay.
• Height, attached: 25 feet. In the Hillside Overlay, 25 feet or the height limit for the existing building, whichever is lower.
• Height, conversion ADU: same as the existing structure.
• Side and rear setbacks: 4 feet minimum.
• Front setback: the city's FAQ says yes, you can place an ADU within the front setback.
• Projections: outside the Hillside Overlay, features like eaves, chimneys and bay windows may project 2 feet into required front and side setbacks if at least 2 feet remains to the property line. Not permitted in the Hillside Overlay.
• Entrance and kitchen: an exterior or independent entrance is required. An ADU needs a kitchen and a full bathroom.

Roof decks are permitted. In the Hillside Overlay, the city says ADU roofs can be used as open space with up to nine extra feet of height "only to enable rooftop access and protective railings." Maximum height is measured from finished grade to the highest point of the roof or parapet walls.

ADUs must also follow Berkeley's Creeks Ordinance and Coast Live Oak Ordinance. Removing or heavily pruning coast live oaks is prohibited. New ADUs must meet Berkeley's Electrification Reach Code. [1][2]

Parking

Parking is not required for ADUs or junior ADUs in Berkeley.

If your ADU replaces a garage, carport or designated uncovered parking space, you may add an uncovered replacement space by right. It may go anywhere on the lot, including within the front setback. A replacement space that needs a new accessory structure must meet the rules in BMC Section 23.304.060. [1]

Fees

Berkeley's Land Use Planning Division charges:

• Zoning plan check: $250, at building permit submittal.
• Neighbor notice: $500, at building permit submittal.
• Address assignment: a non-refundable $250, paid before the building permit is issued. Every ADU except a junior ADU needs its own address.

Land Use Planning does not charge impact fees. Building permit fees depend on the valuation of your project. You can estimate them with the city's permit fee estimator. The estimator leaves out plumbing, mechanical and electrical permit fees, land use fees, school district fees and other agencies' fees.

If your project adds more than 500 square feet of living space, the Berkeley Unified School District charges one-time developer fees. You must give proof of payment to the Permit Service Center before your permit is issued.

If you use a pre-approved design, your plan check fee is 50% of the usual cost. For questions about plan check or permit fees, email the Building and Safety Division at buildingandsafety@berkeleyca.gov. For cost ranges beyond city fees, see our ADU cost guide. [1][2][4][5]

Permit process and timeline

Every ADU and junior ADU needs a building permit. Berkeley reviews your ADU against the zoning standards as part of the building permit. ADUs are not subject to discretionary review, and approved ADU permits are not appealable. A separate zoning permit is generally not needed, except in some cases involving other parts of the project.

You can apply through Permits Online or by appointment at the Permit Service Center. In-person submittals must be PDFs on a USB thumb drive. The center does not accept printouts.

Within 10 working days of your application, city staff mail a courtesy notice to tenants on your property and to owners and tenants of adjacent, confronting and abutting properties. HCD's May 3, 2024 letter said state law "does not require neighbor noticing for an ADU building permit" and asked the city to remove it. Berkeley's current ADU page and its August 2026 info sheet still describe the notice and the $500 fee.

Before the permit is issued, Berkeley asks you to record a deed restriction with the Alameda County Clerk-Recorder. It bars short-term rental and limits selling the ADU separately. In its June 16, 2026 letter, HCD said "Although deed restrictions are required for JADUs, they are prohibited for ADUs." Ask the city whether it still requires one for your ADU.

State law says the city "shall either approve or deny the application" within 60 days of receiving a complete application. If it denies it, it must send a full set of comments listing what is deficient and how to fix it. For the general steps, see our ADU permit process guide. [1][2][3][6][7][8]

Garage and other conversions

A conversion ADU turns an existing accessory building or interior non-livable space into living space. Examples include a garage, workshop, basement, attic or storage room. The converted structure may keep its current size and location, and any existing nonconformities, if it meets fire and safety requirements.

An ADU made entirely by converting existing space, with no change to the building envelope, is allowed even if it is larger than the maximum size. You can add windows, doors or other openings to a lawful nonconforming structure being converted, with a Zoning Certificate. If the conversion requires digging within a required setback, you first need an Administrative Use Permit, then a building permit.

In a duplex or multifamily building, you can convert non-habitable space such as a garage, basement, attic or storage space into an ADU. See our garage conversion guide. [1]

Junior ADUs

A junior ADU must be entirely inside the walls of an existing or proposed single-family home, which includes an attached garage. It can have no more than 500 square feet of interior livable space. It needs its own exterior entrance and at least an efficiency kitchen. If it shares a bathroom with the main home, it also needs an interior entry to the main home.

If the junior ADU shares a bathroom with the main home, the owner must live in either the main home or the junior ADU. That is not required if the junior ADU has its own bathroom, or if the owner is a government agency, land trust or housing organization. A junior ADU cannot have a separate address. More in our junior ADU guide. [1]

Renting, selling and legalizing an ADU

You do not have to live on the property if it has an ADU. You can rent the main home and the ADU to different people. Short-term rental of an ADU or junior ADU is not allowed, except for ADUs established before April 1, 2017 that meet certain criteria.

If you recorded an owner-occupancy restriction under Berkeley's older rules, you can apply to rescind and replace it. The Zoning Officer must approve it in writing, and the city charges a $500 fee for the rescission letter and notarization.

Berkeley allows separate sale of an ADU through an ADU condominium subdivision under BMC Chapter 21.29. The lot must end up with 10 or fewer condominium units, and junior ADUs are not eligible.

If you have an unpermitted ADU or junior ADU on a single-family lot built before January 1, 2020, the city's amnesty program runs from January 1, 2025 to December 31, 2028. You can email UDUamnesty@berkeleyca.gov for a free and confidential consultation. [1][9]

Pre-approved ADU plans

Berkeley's ADU Plans Gallery lists detached ADU designs pre-approved by the City, by HCD or by HUD. They range from small studios to three-bedroom homes.

Before you pick a design, the city asks you to email Land Use Planning at planning@berkeleyca.gov about zoning limits on your property. Then contact the designer, who helps you use the plan. Applications using pre-approved designs pay 50% of the usual plan check fee and often move faster. You cannot change a pre-approved design. If you want changes, you submit it as a new design. [5]

Permit steps in Berkeley

1. Check your zoning and site conditions

   Find your zoning district, and whether you are in the Hillside Overlay, on the Community GIS Portal. Check for creeks and coast live oaks, which have their own rules. [1]

2. Choose a design

   Hire a designer or pick a plan from the ADU Plans Gallery. Before choosing a pre-approved design, email planning@berkeleyca.gov about zoning limits on your lot. [5]

3. Estimate your fees

   Use the city's permit fee estimator. Plan for the $250 zoning plan check fee and $500 neighbor notice fee at submittal. [1][4]

4. Apply for a building permit

   Submit online through Permits Online, or book an appointment at the Permit Service Center and bring PDFs on a USB drive. Include the Address Assignment Request for a new ADU. [1][6][7]

5. Plan check and neighbor notice

   The city mails a courtesy notice to neighbors within 10 working days and reviews your plans against the ADU standards. State law gives the city 60 days from a complete application to approve or deny it. [2][8]

6. Clear the items needed before issuance

   Pay the $250 address fee and give proof of any school district fee payment. The city also asks you to record a deed restriction with the Alameda County Clerk-Recorder before issuance; HCD says this is allowed for junior ADUs but not ADUs, so confirm with the city. [1][2][3]

7. Build and schedule inspections

   After the permit is issued, schedule inspections in Permits Online. The city issues the ADU's address before the final inspection. [2][7]

Pre-approved and sample plans

• Berkeley ADU Plans Gallery

  Detached ADU designs pre-approved by the City, HCD or HUD, from studios to three bedrooms, with a 50% plan check fee reduction. [5]

Who to call

• Land Use Planning Division

  ADU zoning standards and questions about your lot (email planning@berkeleyca.gov)

  (510) 981-7410

  1947 Center St, 2nd Floor, Berkeley, CA 94704

  [1][2]

• Permit Service Center

  Permit applications, by appointment Monday-Thursday, 8:30am-2:30pm

  (510) 981-7500

  1947 Center Street, 3rd Floor, Berkeley, CA 94704

  [6]

• Building and Safety Division

  Plan check and building permit fee questions (email buildingandsafety@berkeleyca.gov)

  (510) 981-7440

  [4]

• Amnesty Program for Unpermitted Dwelling Units

  Legalizing an existing unpermitted ADU or junior ADU

  [9]

Questions people ask