In short
- 1,140 ADU permits since 2018.
- 259 in 2025, up 30% from 2024.
- Typical permit time: 268 days from application to permit (median of 739 permits with both dates recorded).
About this data
- Source: California HCD Housing Element Annual Progress Reports. The state data does not say whether an ADU is detached, attached, a garage conversion or a JADU, so most records show as 'unknown'. Permit valuations are not published in this source. Timelines use the application date the city reported to the state, matched to the permit where possible; some cities report their planning application date, so timelines can include planning review. Each project is counted once, in its building-permit year (or completion year when no permit date was reported).
Permits by year
Permits by year and type (table)
| Year | All ADU permits | Garage conversions | Detached |
|---|---|---|---|
| 2018 | 47 | 1 | 0 |
| 2019 | 59 | — | — |
| 2020 | 66 | 11 | 4 |
| 2021 | 135 | 27 | 42 |
| 2022 | 171 | — | — |
| 2023 | 203 | — | — |
| 2024 | 200 | — | — |
| 2025 | 259 | 43 | 118 |
“—” means the source for that year does not report ADU type.
Read more: ADU types explained
ADU rules in Santa Ana
State law check: No HCD review letter on file; that is not a finding of compliance.
| Rule | Santa Ana's code | State law guarantees |
|---|---|---|
| Maximum size | 1,000 sq ft, attached or detached; attached ADUs 50% of the house (at least 800 sq ft). 800 sq ft when there's also a junior ADU. No cap for conversions. Junior ADU 500 sq ft. | At least 850 sq ft (1,000 sq ft with 2+ bedrooms) must be allowed; an 800 sq ft detached ADU always is. Conversions of existing space have no size cap. Junior ADU: up to 500 sq ft. |
| Height | Detached: 20 ft and 2 stories. Attached: same as the house. No limit for conversions. | Detached: at least 16 ft (18 ft within ½ mile of transit, plus 2 ft for a matching roof). Attached: 25 ft or the zone's limit, whichever is lower. |
| Setbacks | 4 ft side and rear; front setback matches the house, unless that would block an 800 sq ft ADU. 15 ft from the house for a detached ADU (can be reduced for an 800 sq ft ADU). | No more than 4 ft side and rear; none for conversions of existing space. |
| Parking | 1 space for a new ADU unless exempt (transit, historic district, studio, car share, inside existing space); tandem is allowed. No replacement parking for converted garages. | At most 1 space; none within ½ mile of transit and in several other cases. No replacement parking when a garage is converted. |
| Owner living on site | None for ADUs. Junior ADU: the owner lives in the house or the junior ADU, with a recorded covenant. | None for ADUs. A junior ADU that shares a bathroom with the house requires the owner to live in one of them. |
| How many on a single-family lot | One ADU and one junior ADU on a single-family lot. | One ADU converted from existing space, one junior ADU and one new detached ADU (up to 800 sq ft). From January 1, 2027: two new detached ADUs (a city then needn't allow a junior ADU on that lot). |
| Short-term rentals | More than 30 days: rentals under 30 days, including home-sharing, are banned citywide. | No guarantee: cities may require rentals of more than 30 days, and junior ADUs can't be short-term rentals. |
- Historic properties: ADUs must follow the Secretary of the Interior's standards for historic properties.
- Open space: 1,200 sq ft of usable yard on single-family lots, which can be reduced for an 800 sq ft ADU.
- The city offers pre-approved ADU plans.
Where local rules conflict with state law, state law controls. Sources: Santa Ana Municipal Code 41-194.2 and 41-194.3 · Santa Ana Municipal Code 8-3401 (short-term rentals) · City of Santa Ana ADU page; HCD's list of review letters; California ADU rules. Verified Oct 5, 2026. Rules change and every lot is different: confirm with the city before you design.
How long permits take
| Type | Median days, application to permit | Middle half | Permits |
|---|---|---|---|
| Detached ADU | 324 | 197 – 459 | 130 |
| Attached ADU | 294 | 194 – 382 | 28 |
| Garage conversion | 304 | 195 – 380 | 60 |
| Junior ADU (JADU) | too few to say | 3 | |
| Unclassified | 258 | 180 – 380 | 518 |
Middle half: the range covering the middle 50% of permits (a quarter were lower, a quarter higher).
Read more: How long ADUs take to build
From permit to completion
Of the 565 ADU permits Santa Ana reported issuing from 2020 through 2023, 423 (75%) have a completion reported to the state. For those, the median time from permit to completion was 10 months.
The state reports don't record expired or cancelled permits, and a completion the city hasn't reported looks the same as an unfinished project, so the share is a floor. Years with incomplete reports are left out.
What neighbors declared as cost
Cost data (declared permit valuations) is not published for this area in these sources.
Read more: How to choose an ADU builder
An ADU builder serving Santa Ana? Feature your business on this page.
Questions about ADUs in Santa Ana
How many ADUs have been permitted in Santa Ana?
Public records show 1,140 ADU permits in Santa Ana from 2018 through 2025. 259 in 2025, up 30% from 2024. These counts come from the city's reports to the state, which place a project in its completion year when no permit date was reported.
How long does an ADU permit take in Santa Ana?
Among the 739 ADU permits in Santa Ana with both dates recorded, half were issued within 268 days of the application; the middle half took 183 to 390 days. That includes plan-check corrections and resubmittals, not just the review itself.
Can I build an ADU on my property in Santa Ana?
California law allows ADUs on most lots with a house, including in Santa Ana, but what you can build depends on your lot, local rules and utilities. This site shows permits, not eligibility. See California ADU rules.
Where do I apply for an ADU permit in Santa Ana?
Apply with the City of Santa Ana's Planning Division, which also offers pre-approved ADU plans. Official ADU page.
How current is this?
- State annual progress reports: through 2025 (published once a year)
How our data works · Download the data · Free to reuse with credit to SoCal ADU Tracker (socaladutracker.com), under CC BY 4.0.