ADU rules in Berkeley

Detached ADUs are allowed with a ministerial Zoning Certificate on any lot in a district that permits housing and has an existing or proposed home or group living accommodation (fraternities, sororities and dormitories excepted). A lot with one single-family home may have one new-construction ADU (attached or detached), one conversion ADU and one JADU; a lot with an existing multifamily building may add up to 8 new-construction ADUs (never more than its existing units) plus interior conversions, a proposed multifamily building gets 2, and lots with more than one single-family home or a group living accommodation get 1. Table 23.306-2 sets 4-ft rear, interior-side and street-side setbacks and no front setback, and the city FAQ confirms an ADU may sit in the front setback. Table 23.202-1 marks ADUs 'NP' in the ES-R Environmental Safety-Residential district (Panoramic Hill), and the M, MM, MU-LI and M-RD manufacturing districts bar them; a state-exempt unit under Gov. Code 66323 must still be approved in any residential zone, as 23.306.040(A)(2) itself says.

New-construction ADUs 'may be either attached or detached from the main building(s) and/or other ADUs, in any configuration' (Table 23.306-1 note 1), and an ADU counts as attached when it shares a wall with the main home. On a single-family lot an attached addition uses the one new-construction slot, while a conversion ADU (inside the house, a garage or an accessory building) and a JADU of up to 500 sq ft inside the home or its attached garage come on top. In duplexes and multifamily buildings, interior ADUs must be carved from non-habitable space such as basements, attics, garages and storage rooms. Outside the Hillside Overlay, multifamily lots may also add attached new construction, which Ord. 7983-NS (effective 10-9-2025) allowed after HCD's February 25, 2025 letter rejected the city's denial of an attached ADU on a duplex at 1902 Ward Street; inside the Hillside Overlay new ADUs on multifamily lots must be detached.

Conversions of existing space may exceed the cap and add up to 150 sq ft, and a converted accessory building keeps its nonconforming size and location (23.306.030(A)(1), (A)(3)). The caps are gross floor area measured 'within the outer surface of the main walls' (23.106.030), while Gov. Code 66321(b) sets the 850 and 1,000 sq ft floors in interior livable space; HCD's June 16, 2026 findings (item 6) told the city to switch, and where an outside-wall measurement would push a Hillside unit below the state floor, the state floor controls (Gov. Code 66325). Up to 800 sq ft of ADU and JADU area per lot is excluded from lot coverage and floor-area limits (23.106.020(B)(5), 23.106.030(B)(6)). The smaller Hillside caps and 20-ft detached height came with Ord. 7983-NS (adopted 9-9-2025, effective 10-9-2025), whose findings cite wildfire, Hayward Fault and evacuation risk; the city FAQ reads the attached Hillside limit as 20 ft for an addition, matching the overlay's 20-ft cap on residential additions (Table 23.210-1).

No owner-occupancy requirement applies to ADUs; Gov. Code 66315 forbids one, and the city FAQ says an owner with an ADU does not have to live on site. For a JADU, the owner must live in the JADU or the main home only when the two share sanitation facilities, and never when the owner is a governmental agency, land trust or housing organization (23.306.040(C)(4) as restated by Ord. 8007-NS, effective 6-11-2026, matching Gov. Code 66333(b)). Owners holding an older recorded ADU Notice of Limitation from Berkeley's former owner-occupancy rule can apply to rescind and replace it with Zoning Officer approval and a $500 fee (city FAQ).

Table 23.322-1 reads 'Junior ADU: None required / ADU: None required' for residential districts since Ord. 7983-NS § 12 (2025), and the commercial and manufacturing tables (23.322-2, 23.322-4) also say 'None required'. The Hillside Overlay rule requiring one space per unit on roadways narrower than 26 ft applies to main dwellings, not ADUs. Parking lost to an ADU need not be replaced (Gov. Code 66314(d)(11)); any parking an owner chooses to provide for an ADU, or as replacement for the main home, may go anywhere on the lot, including the front setback (23.322.080(G)).

ADUs and JADUs need a Zoning Certificate, reviewed with the building permit and approved or denied within 60 days of a complete application, with a written list of deficiencies on denial; there is no hearing, and the city says approved ADU permits are not appealable. Within 10 working days of submission, staff mail a courtesy notice to tenants on the lot and to owners and tenants of adjacent, confronting and abutting properties ($500 noticing fee, 23.306.040(B)). An ADU that is part of a project needing discretionary review waits for that approval (23.306.040(A)(1)), and the city FAQ says an Administrative Use Permit comes first when a conversion requires excavating within a nonconforming setback. The 15-business-day completeness clock of Gov. Code 66317(a)(2) applies directly even though the code omits it (HCD June 2026 finding 4).

The 30-day floor is written into a deed restriction recorded before the building permit issues (23.306.040(C)(3)); Gov. Code 66315 allows a 30-day minimum, but HCD's June 16, 2026 findings say a deed restriction may not be imposed on an ADU, and 66323(e) and 66333(g) require terms longer than 30 days for state-exempt units and JADUs. Chapter 23.314 allows short-term rentals only in the host's residence and only in ADUs permitted before April 3, 2017 that were never used for long-term rental; the city program requires a Short-Term Rental Zoning Certificate, a $451.25 application fee, 12% transient occupancy tax plus a 2% enforcement fee, and a 90-day yearly cap when the host is away. Ord. 7999-NS (adopted 2-10-2026, effective 3-12-2026) created a ministerial ADU condominium map process (at most 10 condominium units per lot, lienholder consent, no JADUs, and for a rented ADU not fully exempt from rent control the tenant's continued occupancy and a 90-day exclusive right to purchase). Under 13.76.050, ADUs created after June 30, 1980 are 'Partially-covered units' (no rent ceilings, but registration under 13.76.080 and good-cause eviction apply), while the single ADU on a single-family lot where the landlord lives is fully exempt for tenancies begun after November 7, 2018.