In short
- 378 ADU permits on record, nearly all since 2018.
- 82 in 2025, up 15% from 2024.
- Typical permit time: 205 days from application to permit (median of 304 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 |
|---|---|---|---|
| 1999 (partial records) | 1 | — | — |
| 2018 | 20 | 0 | 0 |
| 2019 | 23 | — | — |
| 2020 | 31 | 1 | 0 |
| 2021 | 37 | — | — |
| 2022 | 51 | — | — |
| 2023 | 62 | — | — |
| 2024 | 71 | — | — |
| 2025 | 82 | — | — |
“—” means the source for that year does not report ADU type.
Read more: ADU types explained
ADU rules in El Cajon
State law check: HCD found the city's 2024 ADU ordinance out of line with state law (February 6, 2025). The city has amended it since, but some flagged limits remain; HCD hasn't reviewed the new text.
| Rule | El Cajon's code | State law guarantees |
|---|---|---|
| Maximum size | 1,200 sq ft, attached or detached, but never larger than the house (counting an attached garage). Junior ADU 500 sq ft. Lot coverage and open space can't block a state-law ADU. | 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: the zone's limit inside the house's setbacks; elsewhere 20 ft with a 5 ft setback, 16 ft with 4 ft, 12 ft with 3 ft. 18 ft near transit (plus 2 ft for roof pitch) or next to a two-story house. Attached: 16 ft with a 4 ft setback, 12 ft with 3 ft. | 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 | At least 3 ft side and rear; detached ADUs stay out of the front setback unless that would block an 800 sq ft ADU. Conversions: enough for fire safety. | No more than 4 ft side and rear; none for conversions of existing space. |
| Parking | 1 space per ADU (tandem or in the front setback is fine) unless exempt: transit within ½ mile, conversions, junior ADUs, car share and more. 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 | None for ADUs. Junior ADU: the owner lives in the house or the junior ADU when they share sanitation, with a recorded notice of 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 plus one junior ADU, with the code adding that all combinations in Gov. Code § 66323 are allowed. | 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 | Junior ADU: 30 days or more. The ADU section sets no minimum term for ADUs. | No guarantee: cities may require rentals of more than 30 days, and junior ADUs can't be short-term rentals. |
- No impact fees for ADUs and junior ADUs under 750 sq ft; larger ADUs pay in proportion to the house.
- New ADUs must use materials, colors and a style similar to the house.
- The city's Housing Division runs an ADU Loan Program (deferred loans; the ADU stays affordable for at least 5 years) and offers standard studio, 1-bedroom and 2-bedroom ADU plans.
Where local rules conflict with state law, state law controls. Sources: El Cajon Municipal Code 17.140.180 (amended February 10, 2026) · HCD findings (February 6, 2025) · City of El Cajon ADU Loan Program; 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 |
|---|---|---|---|
| Attached ADU | not reported | ||
| Garage conversion | not reported | ||
| Junior ADU (JADU) | too few to say | 1 | |
| Unclassified | 207 | 134 – 321 | 303 |
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 157 ADU permits El Cajon reported issuing from 2020 through 2023, 127 (81%) 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 El Cajon? Feature your business on this page.
Questions about ADUs in El Cajon
How many ADUs have been permitted in El Cajon?
Public records show 378 ADU permits in El Cajon through 2025, nearly all since 2018. 82 in 2025, up 15% 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 El Cajon?
Among the 304 ADU permits in El Cajon with both dates recorded, half were issued within 205 days of the application; the middle half took 133 to 320 days. That includes plan-check corrections and resubmittals, not just the review itself.
Can I build an ADU on my property in El Cajon?
California law allows ADUs on most lots with a house, including in El Cajon, 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 El Cajon?
Apply with the City of El Cajon's Building Safety Division, submitting plans online through the Project Assistance Center Online (PACO). 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.