California ADU rules · Mendocino County
Can I Build an ADU in Ukiah?
Yes — you can build an ADU in Ukiah. California's statewide ADU law requires every city, including Ukiah, to approve a qualifying accessory dwelling unit by right, plus a junior ADU (JADU) on a single-family lot. What varies city to city are the local specifics below.
Can you build one?
ADUs allowed
CA state lawYes — by right
ADUs and JADUs are allowed by right in all residential and mixed-use zones; ministerial approval, no hearing.
Units on a single-family lot
CA state law1 ADU + 1 JADU
At least one ADU and one JADU per single-family lot (a conversion ADU may also be possible).
Units on a multifamily lot
Local ruleUp to 8 detached ADUs on a lot with an existing multifamily dwelling (2 detached on a proposed multifamily lot) + conversions up to 25% of existing units
On a lot with an existing multifamily dwelling, up to 8 detached ADUs plus conversions of non-livable space up to 25% of existing units — never exceeding the number of existing units. A proposed-multifamily lot is limited to 2 detached ADUs. Tracks state law (SB 1211).
Junior ADU (JADU)
CA state lawAllowed
Up to 500 sq ft, within the walls of an existing single-family home (single-family lots only).
Size & height
Max detached ADU size
Local rule1,200 sq ft
Detached ADU capped at 1,200 sq ft (Ukiah's local maximum, equal to the statewide default), with NO maximum size on a lot with a multifamily structure; conversions of existing accessory structures or part of the primary residence are not subject to a size cap. 800 sq ft remains the state-protected by-right floor, not Ukiah's maximum.
Max attached ADU size
CA state law50% of the primary dwelling, but ≥850 sq ft (≥1,000 sq ft for 2+ bedrooms) is always allowed
Guaranteed minimum size
CA state law800 sq ft
An 800 sq ft ADU must be allowed regardless of FAR/lot-coverage caps; a city also cannot cap an attached ADU below 850 sq ft (1,000 for 2+ bedrooms).
Max JADU size
CA state law500 sq ft
Max height
Local rule20 ft
Ukiah allows detached ADUs up to 20 ft by right (above the 16-ft state floor); a detached ADU over 20 ft may be approved through a minor site development permit (a discretionary path). Attached ADUs and ADUs above a garage may reach 25 ft or the base-zone maximum, whichever is greater, and an ADU may be taller than the primary residence.
Setbacks
Side setback
CA state law4 ft
A city cannot require more than 4 ft side or rear setback; conversions of existing structures are exempt.
Rear setback
CA state law4 ft
Front setback
Local ruleSame as the existing primary residence, but no closer than 5 ft for a new detached ADU over 800 sq ft; no front setback applies to a detached ADU of 800 sq ft or less, or to any detached ADU associated with a multifamily dwelling
Separation from main house
CA state lawNone required
No statewide separation requirement between the ADU and the primary dwelling.
Parking
Parking required
CA state lawUp to 1 space
At most 1 space per ADU (or per bedroom, whichever is less) — and waived in the common cases below.
Transit parking exemption
CA state lawYes — no parking required near transit & for conversions
No parking may be required within ½ mi walking distance of transit, in a historic district, for an ADU within an existing structure, within one block of car-share, or in certain permit-parking areas.
Garage-conversion replacement parking
CA state lawNot required
When a garage/carport is demolished or converted to build an ADU, replacement parking cannot be required.
Approval, timeline & cost
Approval path
CA state lawMinisterial (by right)
No public hearing or discretionary design review for a qualifying ADU.
Approval timeline
CA state law60 days
The agency must act within 60 days of a complete application — and the ADU is deemed approved if it does not.
Owner-occupancy
CA state lawOnly for a JADU
No owner-occupancy requirement for ADUs (the prior sunset was removed). A JADU may require owner-occupancy, principally where it shares sanitation with the main house.
Impact-fee waiver
CA state lawWaived under 750 sq ft
An ADU of 750 sq ft or less pays no impact fees (the 750 sq ft threshold itself is exempt under § 66311.5); larger ADUs pay fees proportional to the primary dwelling. JADUs (≤ 500 sq ft) are exempt.
Permits required
CA state lawBuilding permit
Only a ministerial building permit — no conditional use permit or discretionary design review for a qualifying ADU.
Ukiah has a standalone ADU ordinance — Ukiah City Code Article 5.3 (§§ 9056–9056.7), adopted as Ord. 1244 (2024) and amended by Ord. 1258 (2025) to address HCD compliance findings. The most useful local specifics: detached ADUs may reach 20 ft by right (vs. the 16-ft state floor) and up to 25 ft on a discretionary minor site development permit, attached/over-garage ADUs up to 25 ft, and a 1,200 sq ft detached cap (no cap on multifamily lots). Detached ADUs over 800 sq ft must keep a 5-ft front setback; smaller ones and conversions are exempt. The city also offers three sets of free pre-engineered ADU plans. Confirm fire-resistive construction requirements in the State Responsibility Area with Ukiah Community Development.
Frequently asked questions
Can I build an ADU in Ukiah?
Yes. California's statewide ADU law requires Ukiah to approve a qualifying accessory dwelling unit ministerial (by right), plus a junior ADU (JADU) on a single-family lot.
How big can an ADU be in Ukiah?
A detached ADU of at least 1,200 sq ft must be allowed, and an ADU of 800 sq ft can never be zoned out by floor-area or lot-coverage limits. A JADU can be up to 500 sq ft.
What are the setback requirements for an ADU in Ukiah?
Side and rear setbacks are limited to 4 ft. Same as the existing primary residence, but no closer than 5 ft for a new detached ADU over 800 sq ft; no front setback applies to a detached ADU of 800 sq ft or less, or to any detached ADU associated with a multifamily dwelling.
Is parking required for an ADU in Ukiah?
Up to 1 space. No parking can be required within ½ mile of transit, for conversions, or for units inside the primary home. When a garage is converted, replacement parking is not required.
How long does ADU approval take in Ukiah?
A complete application must be acted on within 60 days, with ministerial (by right) — no public hearing or discretionary design review for a qualifying ADU.
Do I have to live on the property to build an ADU in Ukiah?
Owner-occupancy: only for a jadu. ADUs under 750 sq ft are also exempt from impact fees.
Sources
- Ukiah City Code § 9056 et seq. (Art. 5.3, Accessory Dwelling Units; Ord. 1258)
- Ukiah City Code § 9056.2(B)(2)
- Ukiah City Code § 9056.2(C) (Size)
- Ukiah City Code § 9056.6 (Height)
- Ukiah City Code § 9056.3(A) (Setbacks)
- Cal. Gov. Code §§ 66310–66342 (ADU Law)
- HCD 2025 Accessory Dwelling Unit Handbook
- Cal. Gov. Code § 66317 (ministerial approval, 60-day deadline)
- Cal. Gov. Code § 66323 (by-right ADU/JADU, 800 sq ft, 4-ft setbacks)
- Cal. Gov. Code § 66333 (junior ADUs)
- Cal. Gov. Code § 66321 (size minimums & height)
- Cal. Gov. Code § 66322 (ADU parking; § 66334 covers JADU parking)
- Cal. Gov. Code § 66314 (local ordinance standards)
- Cal. Gov. Code § 66315 (owner-occupancy)
- Cal. Gov. Code § 66311.5 (impact fees: none for an ADU ≤ 750 sq ft or JADU ≤ 500 sq ft)
Last updated 2026-06-28. This is an AI-assisted summary of Ukiah's ADU rules, drawn from its published ordinance and California ADU law — general information, not legal advice, and it may be incomplete or out of date. Verify the controlling rule for your specific parcel with Ukiah Planning before relying on it.
Will an ADU work on your Ukiah lot?
Ask GoCodebook about your address and get the size, setback, parking and permit rules that actually apply to your parcel — with the exact citation.
Check my parcel free