Everything homeowners need to know about building an accessory dwelling unit in Berkeley - size limits, setbacks, permits, and how a city that once pioneered exclusionary zoning has become one of the more ADU-friendly places in the Bay Area.
Last verified: August 2026
9/10 · Very ADU-friendly
1,000 sq ft*
Max ADU size
20 ft*
Max height
Not required
Owner-occupancy
By-right
Permit type
This page summarizes Berkeley Municipal Code Chapter 23.306 (Accessory Dwelling Units), effective March 17, 2022, together with California's statewide ADU law, for general reference - it is not legal advice. Regulations change; always confirm current requirements with Berkeley's Land Use Planning Division before designing or applying for permits. See sources below.
Zoning & size requirements
What you're allowed to build
ADU type
Max size
Max height
Notes
Detached / attached new construction (outside Hillside Overlay)
850 sq ft for a studio or one-bedroom unit; 1,000 sq ft for two or more bedrooms
20 ft
4 ft minimum side and rear setbacks; front setback follows the zoning district
Detached / attached new construction (within Hillside Overlay)
800 sq ft
16 ft
Roof decks and balconies are not permitted on Hillside Overlay ADUs
May exceed the standard size limits; up to a 150 sq ft physical addition allowed if no changes are made to the existing building envelope
Maintains the existing structure's height
Common lowest-cost path for a Berkeley ADU
Junior ADU (JADU)
500 sq ft maximum
Within the walls of the primary dwelling, including an attached garage
Parking replacement not required if built into an attached garage
Allowed zoning districts
Any lot zoned for residential use, citywide, with an existing or proposed dwelling - including lots with an existing duplex or apartment building. ADUs are not subject to lot size, density, or coverage limits. Confirm whether your parcel falls within the Hillside Overlay District, since it changes your size and height caps, with the Land Use Planning Division.
Additional standards
Setbacks, parking & other rules
Setbacks
4 ft minimum from side and rear property lines; front setback follows the underlying zoning district
Parking
Not required outside the Hillside Overlay District. Within the Hillside Overlay, parking is required unless the lot sits within a half mile of a public transit stop. Never required for a JADU
Units per lot
1 ADU plus 1 JADU on a single-family lot. Multifamily lots (existing duplex or apartment building) can add conversion ADUs up to 25% of existing units, or up to 2 detached ADUs under the city's current local ordinance - note state law (SB 1211, 2024) allows up to 8 detached ADUs on multifamily lots, so confirm the city's most current standard with Planning
Owner-occupancy
Not required for a standard ADU. For a JADU, the property owner must live in either the primary residence or the JADU itself
Building code
Must meet current California Residential Code and Title 24 energy standards; ADUs are also subject to Berkeley's Creeks Ordinance where applicable
Rental license
Most rental property owners need a City of Berkeley business license, and covered units generally must register with the Berkeley Rent Board. New ADUs are typically exempt from rent-control rate caps under state law (Costa-Hawkins), but confirm registration and eviction-protection requirements with the Rent Board
Ordinance history
How Berkeley's ADU rules got here
1916Berkeley invents single-family zoning. The city enacted the first single-family zoning ordinance in the United States, explicitly intended to exclude Black and Asian residents from parts of the city - a history that shapes how the city talks about zoning reform today.
2017Statewide by-right approval begins. Berkeley adopted Ordinance No. 7,536-N.S. on March 14, 2017, amending its zoning code to conform to California's newly strengthened ADU law (AB 2299 and SB 1069).
2020State law tightens further. AB 68, AB 881, AB 587, AB 2299, and AB 671 expanded size allowances, cut parking requirements, and sped up review timelines statewide; Berkeley updated its ordinance to match.
2021City votes to end single-family zoning citywide. By a unanimous 9-0 vote, the City Council began a process to overturn its own 1916 ordinance and allow multi-unit housing citywide, becoming the first city in California to do so - part of a broader push tied to the city's state-mandated goal of 9,000 new homes by 2031.
2022Current ADU ordinance takes effect. The updated Berkeley Municipal Code Chapters 23.306 and 12.99 became effective March 17, 2022, setting the size, height, and parking standards in place today.
2026Berkeley becomes an AB 1033 early adopter. On January 21, 2026, the City Council voted 6-1 to let ADUs be sold separately from the primary home as condominiums under state law AB 1033.
Worth knowing: Berkeley issued building permits for 95 ADUs in 2023 alone, bringing the citywide cumulative total to roughly 602 since 2016 when state law first accelerated approvals - part of an estimated 2,761 new ADUs built across the Bay Area that year, per regional reporting.
Permit process
How Berkeley ADU permitting works
1
Pre-application check
Confirm whether your lot is in the Hillside Overlay District, since it changes your size, height, and parking requirements, before you design.
2
Prepare your plan set
You'll need a site plan, floor plans and elevations for the ADU, and Title 24 energy compliance forms.
3
Submit through the Permit Service Center
File your building permit application online through Berkeley's Permit Service Center (PSC) portal. A $500 fee covers the required notice to neighbors at submittal.
4
Plan review
The city reviews for zoning and building code compliance within a 60-day ministerial review window; under state law (SB 543, effective Jan. 1, 2026) the project is deemed approved if the city misses that deadline.
5
Building permit & inspections
Once approved, pay your valuation-based building permit fee, pull the permit, and schedule the standard framing, plumbing, electrical, and final inspections.
6
Rent Board registration (if renting)
If you'll rent the ADU long-term, register with the Berkeley Rent Board and confirm your business license status before placing tenants.
Fees and timelines are approximate - confirm current figures with the Land Use Planning Division. Note that ADUs established after April 1, 2017 cannot be used as short-term rentals in Berkeley.
Budgeting
What it costs to build an ADU in Berkeley
Garage conversion
Roughly $70,000-$180,000, the least expensive path since the shell already exists
Basement conversion
Roughly $100,000-$220,000, depending on existing ceiling height and utility access
New detached ADU
Roughly $150,000-$350,000+ for a code-compliant freestanding unit; Berkeley's Bay Area land and labor costs tend to push toward the higher end
City permit fees
$250 zoning plan check, $500 neighbor-noticing fee, and $250 address assignment at submittal, plus a valuation-based building permit fee (about $2.40 per $100 of value over $3,000, plus a $62.50 filing fee)
All-in permit total
Typically $8,000-$18,000 depending on project valuation; Berkeley Unified School District facility fees also apply on units over 500 sq ft of livable space
These are general ranges from local contractor estimates and regional reporting, not quotes - actual cost depends heavily on lot conditions, finishes, and whether utilities need to be extended. Building within the Hillside Overlay's tighter footprint can also add site-specific costs like retaining walls or geotechnical review.
Before you apply
Tips for a smooth approval
Confirm your Hillside Overlay status before you design. It changes your size cap (800 vs. 850/1,000 sq ft), height limit (16 vs. 20 ft), and whether parking is required.
Consider a conversion if you have existing accessory space. Converting an existing legal structure can exceed the standard size limits and even qualifies for a small 150 sq ft addition.
Budget for the $500 neighbor-noticing fee separately. It's collected at submittal alongside the zoning plan check and address assignment fees, before your building permit fee is even calculated.
If you're planning to sell the ADU separately, ask about AB 1033. Berkeley's January 2026 condo-conversion ordinance is new - confirm current procedures and any HOA-style requirements with Planning before you finalize plans.
Decide on rental plans before you build. Long-term rentals generally need Rent Board registration and a business license - it's easier to plan the layout and paperwork together from the start.
FAQ
Common questions
Do I need to live on the property to build an ADU in Berkeley?
No. There is no owner-occupancy requirement for a standard ADU in Berkeley. For a JADU, the property owner must live in either the primary residence or the JADU itself.
How many ADUs can I build on one lot?
One ADU plus one JADU on a single-family lot. Multifamily lots can add conversion ADUs up to 25% of existing units, or up to 2 detached ADUs under the city's current local ordinance - though state law (SB 1211, 2024) allows up to 8 detached ADUs on multifamily lots statewide, so confirm the city's current standard with Planning.
Do I need extra parking for an ADU?
No, outside the Hillside Overlay District. Within the Hillside Overlay, parking is required unless your lot is within a half mile of a public transit stop. Parking is never required for a JADU.
What's the maximum size for a detached ADU?
Outside the Hillside Overlay: 850 sq ft for a studio or one-bedroom unit, or 1,000 sq ft for two or more bedrooms, with a 20 ft height limit. Within the Hillside Overlay: 800 sq ft with a 16 ft height limit.
Can I sell my ADU separately from my house?
As of January 2026, Berkeley is an early adopter of state law AB 1033, which lets cities opt in to allowing ADUs to be sold separately as condominiums. The City Council approved the implementing ordinance on January 21, 2026 - confirm current procedures with Planning, since this is a new program.
How much does an ADU cost to build in Berkeley?
Garage conversions tend to run roughly $70,000-$180,000, basement conversions $100,000-$220,000, and new detached units $150,000-$350,000 or more, based on local contractor estimates and regional reporting - not counting the roughly $8,000-$18,000 in typical city permit fees.
How many ADUs has Berkeley actually permitted?
The city issued building permits for 95 ADUs in 2023, bringing the cumulative total to roughly 602 since 2016 - part of an estimated 2,761 new ADUs built across the Bay Area that year, per regional reporting.
Can I rent my ADU out on Airbnb or a short-term rental platform?
No. ADUs established after April 1, 2017 cannot be used as short-term rentals in Berkeley under city code (BMC 23.314.040).
