In short
- 76 ADU permits since 2018.
- 16 in 2025.
- Typical permit time: 48 days from application to permit (median of 14 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).
- Tustin reported the building-permit date as the application date for most of its ADUs in 2021 and 2024, so approval times for those years can't be measured from the state reports and are left out.
Permits by year
Permits by year and type (table)
| Year | All ADU permits | Garage conversions | Detached |
|---|---|---|---|
| 2018 | 4 | — | — |
| 2019 | 6 | — | — |
| 2020 | 7 | — | — |
| 2021 | 10 | — | — |
| 2022 | 13 | — | — |
| 2023 | 6 | — | — |
| 2024 | 14 | 0 | 0 |
| 2025 | 16 | 0 | 0 |
“—” means the source for that year does not report ADU type.
Read more: ADU types explained
Not counted above: 1 approved projects with no building permit reported yet.
ADU rules in Tustin
State law check: HCD sent a technical-assistance letter (February 27, 2026) noting the city's ordinance on file is from 2021 and may be outdated; no formal findings.
| Rule | Tustin's code | State law guarantees |
|---|---|---|
| Maximum size | Detached: 850 sq ft (studio or 1 bedroom) or 1,200 sq ft (2+ bedrooms). Attached: the same caps or 50% of the house, whichever is less. 850 sq ft detached 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: 16 ft (18 ft near transit, plus 2 ft for roof pitch). Attached: 25 ft or the zone limit, 2 stories. | 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 zone. Detached ADUs go behind the front of the house. None for conversions. | No more than 4 ft side and rear; none for conversions of existing space. |
| Parking | 1 space per ADU or per bedroom, whichever is less, unless exempt (transit, historic district, car share, inside existing space). 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 deed restriction. | 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 (attached, converted or detached) 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, for ADUs and junior ADUs. | No guarantee: cities may require rentals of more than 30 days, and junior ADUs can't be short-term rentals. |
- Converting an attached garage to a junior ADU requires replacing the lost parking under the city code; HCD's letter says parking can't be required for a junior ADU, even in a garage.
- Porches or patios up to 200 sq ft; ADU plus porch no more than 1,400 sq ft.
- Historic properties: original windows, doors and features must stay where possible.
Where local rules conflict with state law, state law controls. Sources: Tustin City Code 9279 · Tustin City Code 9263 (parking) · HCD letter (February 27, 2026); 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 |
|---|---|---|---|
| Junior ADU (JADU) | not reported | ||
| Unclassified | 48 | 7 – 133 | 14 |
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 36 ADU permits Tustin reported issuing from 2020 through 2023, 23 (64%) have a completion reported to the state. For those, the median time from permit to completion was 7 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 Tustin? Feature your business on this page.
Questions about ADUs in Tustin
How many ADUs have been permitted in Tustin?
Public records show 76 ADU permits in Tustin from 2018 through 2025. 16 in 2025. 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 Tustin?
Among the 14 ADU permits in Tustin with both dates recorded, half were issued within 48 days of the application; the middle half took 7 to 133 days. That includes plan-check corrections and resubmittals, not just the review itself.
Can I build an ADU on my property in Tustin?
California law allows ADUs on most lots with a house, including in Tustin, 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 Tustin?
Apply with the City of Tustin's Community Development Department through a building permit application. 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.