In short
- 167 ADU permits since 2018.
- 36 in 2025, up 20% from 2024.
- Typical permit time: 175 days from application to permit (median of 87 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 | 10 | — | — |
| 2019 | 5 | — | — |
| 2020 | 6 | — | — |
| 2021 | 29 | — | — |
| 2022 | 30 | — | — |
| 2023 | 21 | — | — |
| 2024 | 30 | — | — |
| 2025 | 36 | — | — |
“—” means the source for that year does not report ADU type.
Read more: ADU types explained
Not counted above: 106 approved projects with no building permit reported yet.
ADU rules in Yorba Linda
State law check: HCD sent a technical-assistance letter (December 5, 2025) noting the city's ordinance on file is from 2020 and may be outdated; no formal findings.
| Rule | Yorba Linda's code | State law guarantees |
|---|---|---|
| Maximum size | Attached: 800 sq ft (studio or 1 bedroom) or 1,000 sq ft (2 to 3 bedrooms), or 50% of the house. Detached: 800 or 1,000 sq ft; 1,200 sq ft on lots of 15,000 sq ft with design review. 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 on multifamily lots). Attached: 25 ft, 2 stories. A two-story ADU needs a conditional use permit. | 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 per the zone. ADUs over 1,000 sq ft or taller than one story use the zone's setbacks. Detached ADUs 10 ft from other buildings. | No more than 4 ft side and rear; none for conversions of existing space. |
| Parking | 1 space in a garage or on the driveway, unless exempt (transit, inside existing space, permit parking, built with a new home). No replacement parking. | 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 | Not stated in the city's ADU information sheet. | 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. | 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 | 31 consecutive days or more; the city bans all short-term rentals. | No guarantee: cities may require rentals of more than 30 days, and junior ADUs can't be short-term rentals. |
- The city's ADU application asks for a list of adjacent owners for neighbor notification.
- Planning application fees for ADUs are waived through June 30, 2029.
- Check for methane, oil wells, fire hazard zones and septic systems early; these can affect an ADU.
- The city has a pre-approved detached ADU plan program.
Where local rules conflict with state law, state law controls. Sources: Yorba Linda ADU information sheet (2025), YLMC 18.20.800 · HCD letter (December 5, 2025); 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 |
|---|---|---|---|
| Unclassified | 175 | 114 – 280 | 87 |
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 84 ADU permits Yorba Linda reported issuing from 2020 through 2023, 50 (60%) have a completion reported to the state. For those, the median time from permit to completion was 11 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 Yorba Linda? Feature your business on this page.
Questions about ADUs in Yorba Linda
How many ADUs have been permitted in Yorba Linda?
Public records show 167 ADU permits in Yorba Linda from 2018 through 2025. 36 in 2025, up 20% 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 Yorba Linda?
Among the 87 ADU permits in Yorba Linda with both dates recorded, half were issued within 175 days of the application; the middle half took 114 to 280 days. That includes plan-check corrections and resubmittals, not just the review itself.
Can I build an ADU on my property in Yorba Linda?
California law allows ADUs on most lots with a house, including in Yorba Linda, 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 Yorba Linda?
Apply with the City of Yorba Linda: an ADU application to the Planning Division, then a building permit from the Building Division. 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.