Everything homeowners need to know about building an accessory dwelling unit in Santa Ana - size limits, setbacks, permits, and how one of California's most densely built cities makes ADUs work on small, older lots.
Last verified: August 2026
8/10 · 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 California's statewide ADU law and Santa Ana Municipal Code Section 41-194 (Accessory and Junior Accessory Dwelling Unit Standards) for general reference - it is not legal advice. Regulations change; always confirm current requirements with the Santa Ana 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 (new build or garage conversion)
1,000 sq ft
20 ft, up to two stories
Must comply with Municipal Code Section 41-194 development standards
1,000 sq ft or 50% of the primary dwelling's floor area, whichever is smaller
Matches the height allowed for the primary dwelling in the underlying zoning district
Common approach for garage or above-garage conversions
Junior ADU (JADU)
Up to 500 sq ft, within an existing or proposed single-family home
Matches the underlying zoning district for the primary building
Not permitted on multifamily lots
Allowed zoning districts
R1 (single-family), R2 (two-family), R3 and R4 (multiple-family/suburban apartment), and residential uses within qualifying Specific Development or Specific Plan areas. No minimum lot size is required to build an ADU, which matters in a city as densely built as Santa Ana - one of the most densely populated cities in California, with many single-family lots well under half an acre.
Additional standards
Setbacks, parking & other rules
Setbacks
4 ft from side and rear property lines (the state minimum); front setback follows the underlying zoning district; no additional setback required to convert an existing structure or space
Parking
One space required for a newly constructed ADU, waived if the ADU is within a half mile of public transit, converted from existing space, in a historic district, on a lot without assigned on-street parking permits, near a car-share location, or a studio-style unit; no parking required for a JADU
Units per lot
One ADU and one JADU on a single-family lot; qualifying multifamily properties can add up to eight detached ADUs (not exceeding the number of existing units) plus additional conversion units from non-livable space; JADUs aren't permitted on multifamily lots
Owner-occupancy
Not required for a standard ADU; required for a JADU, with owner-occupancy of either the single-family residence or the JADU
Building code
Must meet current California Residential Code standards as locally adopted
Rental
Confirm current business license and rental registration requirements with the city if you plan to rent either unit
Ordinance history
How Santa Ana's ADU rules got here
2017Statewide by-right ADU approval begins. California law requires cities to ministerially approve qualifying ADU applications, without discretionary review or a conditional use permit.
2020State law tightens further. A package of bills (AB 68, AB 881, AB 587, AB 2299, AB 671) shrinks what cities can restrict and expands by-right approval statewide.
2024Owner-occupancy eliminated; multifamily ADUs expanded. AB 976 permanently bars California cities from requiring owner-occupancy for standard ADUs; SB 1211 lets qualifying multifamily properties add up to eight detached ADUs.
2025Santa Ana updates its ADU ordinance. The City Council approves Zoning Ordinance Amendment 2024-03 in January, updating Municipal Code Sections 41-194 through 41-194.3 to bring the city's ADU standards into compliance with SB 1211 and other recent state law changes.
Santa Ana's ordinance has been actively updated to track state law changes, most recently in January 2025. Because there's no minimum lot size for an ADU, the ordinance works even on the compact, older single-family lots common throughout the city - though the one-space parking requirement for newly built ADUs is a real constraint worth planning around on lots without room to add parking.
Permit process
How Santa Ana ADU permitting works
1
Pre-application review
Confirm your zoning district and whether your project qualifies for one of Santa Ana's pre-approved ADU plans before designing custom.
2
Prepare your plan set
You'll need a site plan, floor plans and elevations for the ADU, and, if size is calculated as a percentage of your home, plans showing the existing house.
3
Submit through E-Plan
Santa Ana's electronic plan review system handles ADU and JADU submittals; ministerial review is capped at 60 days from a complete application under state law.
4
Plan check and revisions
Address any plan check comments from Building, Planning, and Public Works.
5
Building permit & inspections
Pull your building permit and schedule the standard framing, plumbing, electrical, and final inspections.
6
Final approval
Get sign-off before occupying or renting the unit, and confirm any required rental registration.
Fees and timelines are approximate - confirm current figures with the Planning Division before you apply.
Budgeting
What it costs to build an ADU in Santa Ana
Garage conversion
Roughly $75,000-$170,000, the least expensive path since the shell and foundation already exist
New detached ADU
Roughly $180,000-$330,000+ depending on finishes and site conditions
Attached addition / above-garage unit
Costs vary based on whether utilities and structural work are needed; get multiple contractor bids
Added parking space (if triggered)
Budget for adding a parking space on new-construction ADUs that don't qualify for one of the parking exemptions
CalHFA ADU grant
Qualifying homeowners may be eligible for up to $25,000 in state pre-development cost assistance through CalHFA, subject to fund availability
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.
Before you apply
Tips for a smooth approval
Ask about pre-approved plans first. Using one of the city's pre-approved ADU plan sets can meaningfully shorten your review time compared with a fully custom design.
Check whether a parking exemption applies before budgeting for a new space. Several common situations, including proximity to transit and converting existing space, waive the one-space parking requirement.
Confirm your unit mix early. Whether you're building an ADU, a JADU, or both changes your owner-occupancy obligations and size limits, so decide before you design.
Small lot? Don't assume you're excluded. Santa Ana has no minimum lot size for an ADU, so many of the city's smaller, older single-family parcels qualify.
Budget separately for utility connections. Decide early whether the ADU will share utilities with the main house or get its own metered connections, since that affects both cost and permitting.
FAQ
Common questions
Do I need to live on the property to build an ADU in Santa Ana?
No, not for a standard ADU. Owner-occupancy hasn't been required for ADUs statewide since a 2024 change in California law (AB 976). A junior ADU (JADU) still requires the owner to occupy either the primary home or the JADU.
How many ADUs can I build on one lot?
One ADU and one JADU on a single-family lot. Qualifying multifamily properties can add up to eight detached ADUs under a 2024 state law change (SB 1211).
Do I need extra parking for an ADU?
Only for a newly constructed ADU, and even then several common exemptions apply, including being within a half mile of public transit or converting existing space. No parking is required for a JADU.
How long does the permit process take?
State law caps ministerial review at 60 days from a complete application; using one of Santa Ana's pre-approved ADU plans can shorten the process further.
What's the maximum size for a detached ADU?
Up to 1,000 sq ft, with a 20 ft height limit and up to two stories, per the Santa Ana Municipal Code.
Is there a minimum lot size to build an ADU?
No. Santa Ana doesn't impose a minimum lot size, which matters given how many of the city's single-family lots are smaller and older.
How much does an ADU cost to build in Santa Ana?
Garage conversions tend to run roughly $75,000-$170,000, and new detached units commonly run $180,000-$330,000 or more, based on local contractor estimates and regional reporting, not counting permit fees.
Can I rent my ADU out on Airbnb or a short-term rental platform?
Confirm current short-term rental rules with the city before finalizing your design, since those rules are handled separately from ADU zoning.
Did Santa Ana's ADU rules recently change?
Yes. The City Council updated its ADU ordinance in January 2025 (Zoning Ordinance Amendment 2024-03) to reflect SB 1211 and other recent changes to state ADU law.
