California ADU rules · Orange County
Can I Build an ADU in Santa Ana?
Yes — you can build an ADU in Santa Ana. California's statewide ADU law requires every city, including Santa Ana, 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 ruleConversion ADUs (≥1, up to 25% of units) + up to 8 detached on an existing MF lot; up to 2 detached on a proposed MF lot
Detached count is capped at 2 on a proposed (new-construction) multifamily lot — Santa Ana specifies this where the state floor speaks mainly to existing MF lots.
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 rule1,000 sq ft
Detached ADU capped at 1,000 sq ft; reduced to 800 sq ft where both an ADU and a JADU are built on the same lot.
Max attached ADU size
Local ruleUp to 50% of the primary residence's habitable space, but at least 800 sq ft is always allowed, and in no case more than 1,000 sq ft
Santa Ana sets a hard 1,000 sq ft ceiling on an attached ADU — below the state guarantee of up to 1,000 sq ft for a 2+ bedroom unit only, so a 2+ bedroom attached ADU still reaches 1,000 sq ft.
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
Detached ADUs may reach 20 ft and 2 stories; attached ADUs and JADUs match the primary building; conversion ADUs are not subject to a height limit.
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 primary building's zoning district, except an ADU up to 800 sq ft may encroach into the front yard
Separation from main house
Local rule15 ft
Santa Ana requires 15 ft between a detached ADU and the primary dwelling (state law sets none), but this may be reduced to allow an ADU up to 800 sq ft and does not apply to conversions.
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.
Santa Ana-specific factors that can change the answer
State law sets the floor, but these local conditions often decide whether a specific parcel works.
Historic districts & landmark properties
ADUs and JADUs on historic properties must conform to the U.S. Secretary of the Interior's Standards for the Treatment of Historic Properties, an objective design overlay the standard ADU otherwise avoids.
Santa Ana's 2025 ordinance caps a detached ADU at 1,000 sq ft (dropping to 800 sq ft when a JADU is also built), holds attached ADUs to 1,000 sq ft, and sets a distinctive 15-ft separation between a detached ADU and the main house — relaxed for units up to 800 sq ft. Detached ADUs may reach 20 ft / 2 stories, and historic-property ADUs must meet the Secretary of the Interior's Standards.
Frequently asked questions
Can I build an ADU in Santa Ana?
Yes. California's statewide ADU law requires Santa Ana 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 Santa Ana?
A detached ADU of at least 1,000 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 Santa Ana?
Side and rear setbacks are limited to 4 ft. Same as the primary building's zoning district, except an ADU up to 800 sq ft may encroach into the front yard.
Is parking required for an ADU in Santa Ana?
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 Santa Ana?
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 Santa Ana?
Owner-occupancy: only for a jadu. ADUs under 750 sq ft are also exempt from impact fees.
Sources
- Santa Ana Mun. Code §§ 41-194.2–41-194.4 (Ord. No. NS-3076)
- Santa Ana Mun. Code § 41-194.2(C)-(G)
- Santa Ana Mun. Code Table 41-194.3(B)
- Santa Ana Mun. Code Table 41-194.3(A)
- Santa Ana Mun. Code Table 41-194.3(E)
- Santa Ana Mun. Code Table 41-194.3(F)
- Santa Ana Mun. Code Table 41-194.3(K)
- Santa Ana Mun. Code § 41-194.4
- 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 2026-06-25. This is an AI-assisted summary of Santa Ana'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 Santa Ana Planning before relying on it.
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