California permitted 88,885 accessory dwelling units between 2013 and 2022 — a 31× increase over nine years and almost certainly the largest housing-supply expansion ever achieved by zoning reform alone. But the headline hides three uncomfortable details: ADU permits are extraordinarily concentrated, ordinance friendliness is necessary but not sufficient to drive adoption, and one in three California cities permitted fewer than ten ADUs across the entire nine-year window. This is what the public permit data actually shows.
California's modern ADU era began on January 1, 2017, when SB 1069 and AB 2299 took effect and stripped cities of much of their discretionary review authority. Statewide permits jumped from 1,336 in 2016 to 5,154 in 2017 — a near-quadrupling in twelve months. The 2017 reforms were designed to be hard for cities to resist; on this measure they worked.
The 2017 jump was followed by a second, larger one in 2019 when SB 13, AB 68, and AB 881 took effect. That bundle of bills extended state preemption further: it banned owner-occupancy requirements, capped impact fees, mandated 60-day ministerial review, and required cities to allow JADUs alongside ADUs. Permits jumped from 8,890 in 2018 to 12,616 in 2019, a 42 percent year-over-year increase that — unlike 2017 — sustained through 2020.
The COVID year flattened activity at almost exactly 2019 levels (12,655 permits in 2020), then the recovery bent sharply upward. 2021 came in at 20,517 and 2022 at 24,851. The 2021–2022 growth rate of 21 percent suggests the curve has not yet plateaued. AB 2221 (front-yard ADUs, ministerial-review tightening) and AB 976 (extended owner-occupancy preemption to 2030) both took effect in 2023; their impact will be visible when HCD publishes 2023 totals.
The Big West Coast ADU Dataset attributes 77,634 city-issued ADU permits to specific California cities (a further 11,251 are attributed to county jurisdictions). Within the city total, ten cities account for 53 percent. Twenty-five cities account for 63 percent. The other 444 cities in the dataset share the remaining 37 percent.
Los Angeles alone permitted 27,125 ADUs over the nine-year window — 35 percent of all city-issued California ADU permits. No other city is close. San Diego is second with 2,891. The combined total of San Francisco, San Jose, Oakland, and Long Beach — the four other Bay Area / coastal-Southern California metros most often called out as ADU success stories — is 7,082 permits, barely a quarter of LA's count.
LA's dominance reflects three converging factors: the country's largest housing-affordability gap (driving homeowner demand), the country's most permissive locally-adopted ADU ordinance among large cities (UC Berkeley graded LA's ordinance an A− in their 2020 Scorecard), and a vast supply of single-family lots with detached garages eligible for conversion. The next chapter of California ADU growth depends on whether other large cities — particularly Sacramento, Fresno, Bakersfield, and the Inland Empire — see similar dynamics emerge.
| # | City | Permits 2013–22 | % of CA | Share (vs LA) |
|---|---|---|---|---|
| 1 | Los Angeles | 27,125 | 34.9% | |
| 2 | San Diego | 2,891 | 3.7% | |
| 3 | San Francisco | 2,178 | 2.8% | |
| 4 | San Jose | 1,990 | 2.6% | |
| 5 | Oakland | 1,483 | 1.9% | |
| 6 | Long Beach | 1,431 | 1.8% | |
| 7 | Santa Maria | 1,226 | 1.6% | |
| 8 | Garden Grove | 1,113 | 1.4% | |
| 9 | Glendale | 880 | 1.1% | |
| 10 | Burbank | 835 | 1.1% | |
| 11 | Encinitas | 724 | 0.9% | |
| 12 | Santa Barbara | 639 | 0.8% | |
| 13 | Berkeley | 623 | 0.8% | |
| 14 | Sacramento | 616 | 0.8% | |
| 15 | Santa Cruz | 534 | 0.7% |
UC Berkeley's Center for Community Innovation graded California ADU ordinances in 2020. They evaluated 424 jurisdictions across criteria including parking requirements, owner-occupancy rules, fee structures, design review, and clarity of submittal requirements. Cities received letter grades A through F.
Cross-referencing the Scorecard grades against permit volume produces a more nuanced result than housing advocates typically assume. A-grade cities permit more on average than D or F-grade cities — but the average is dragged upward by Los Angeles. Removing LA, the median A-grade city permitted 72 ADUs over the nine-year window. The median B-grade city permitted 183 — more than double the A-grade median. The median C-grade city permitted 80; D-grade 87; F-grade 142.
What this almost certainly means: the Scorecard captures whether a city has gotten out of homeowners' way procedurally, not whether homeowners want to build. A small city with a perfect ordinance and few aging-in-place homeowners willing to add backyard rentals will have a high grade and low permit volume. A larger city with a moderately permissive ordinance, severe housing pressure, and lots of convertible garages will have a B or C grade and high permit volume. The grade is necessary — the cities that block ADUs through procedural friction can effectively zero-out adoption — but it is not sufficient.
The Scorecard predicts whether a city has built the off-ramp. It does not predict whether anyone is on the highway.
Of the 469 California cities for which the Big West Coast Dataset records ADU permit activity, 137 cities — almost one in three — permitted fewer than ten ADUs across the entire 2013–2022 window. Thirty-nine cities permitted exactly zero. Two hundred and fifty-three cities (54 percent of the sample) permitted fewer than fifty.
Three hypotheses explain the long tail. First, housing-stock incompatibility: many small Central Valley and Inland Empire cities have older housing without garages or basements suitable for conversion, and lot sizes that make detached new-build economically marginal at construction costs of $300+ per square foot. Second, demographic mismatch: ADUs are disproportionately built by homeowners aged 55–75 who want a rental income stream or housing for a family member. Cities with younger or more transient populations show lower adoption regardless of ordinance quality. Third, post-preemption knowledge gaps: many small-city homeowners simply do not know that state law has overridden their city's restrictive 2015-era ADU ordinance, and city planning departments — particularly those that opposed the preemption legislatively — have little incentive to publicise the new rules.
The third explanation is the only one a state housing policy can address. The 2024 California ADU Handbook update from HCD attempts to do exactly this; whether the next dataset (2023–2025 permits, expected 2026 from HCD) shows narrowing or widening of the long tail will be the leading indicator of whether ADUs become a statewide tool or remain an LA-plus-coastal-metros phenomenon.
Three legislative changes since 2022 will shape the 2023–2025 numbers, and the early indicators suggest growth has continued. AB 1033, effective January 2024, allows ADUs to be sold separately from the main residence in cities that opt in. Berkeley, San Diego, San Jose, and Oakland have all opted in or are advancing opt-in ordinances; this creates an entirely new sub-market: ADUs as for-sale condominium units rather than family-only or rental supplements. AB 2221 (effective 2023) reduced minimum setbacks and permitted front-yard ADUs in many lot configurations. AB 1332 (effective 2025) created the pre-approved ADU plan framework — cities like Burbank, San Diego, San Jose, Sacramento, Anaheim, Garden Grove, and Santa Ana have rolled out programs that issue building permits in 30 days when an applicant uses a city-pre-approved design.
If the 2021–2022 trend continues, 2023 will likely cross 30,000 statewide permits and 2026 should approach 50,000. That projection is fragile — it depends on construction-cost inflation moderating, on rental demand staying strong enough to underwrite the financing math, and on no significant rollback of state preemption. The single biggest risk to the trajectory is not legislative; it is interest rates. ADUs are debt-financed for the median homeowner who builds one, and the cost of that debt has materially shifted since 2022.
What the next dataset will not show, but that homeowners should watch, is the ratio of detached new-builds to garage conversions. The economics of the two are radically different — a $400/sqft detached new-build at 750 sqft is a $300,000 capital project; a $200/sqft garage conversion at 400 sqft is $80,000. As construction costs continue to outpace wage growth, the conversion share will likely rise, and the absolute permit count may grow more slowly than the project-count would otherwise predict.
Permit data: Big West Coast ADU Dataset published by BuildinganADU.com, drawn from city building-department records aggregated and normalised by Karen Chapple's research team at the UC Berkeley Center for Community Innovation. Coverage runs from 2013 through 2022 calendar years. The dataset attributes 88,885 ADU permits to California jurisdictions; 77,634 are attributed to specific cities and 11,251 to unincorporated county areas. The dataset does not separate JADUs from ADUs; some city permit records did, others did not. We use the combined ADU+JADU category throughout this analysis.
Ordinance grades: California ADU Scorecard 2020, UC Berkeley Center for Community Innovation, Appendix C. Grades reflect the legal text of each city's adopted ADU ordinance as of the 2020 evaluation. Subsequent state legislation (AB 2221, AB 976, AB 1033) raised the floor for every city; cities that have not updated their ordinances to reflect post-2020 state law may have effectively higher or lower grades than the Scorecard indicates depending on how much the local text now contradicts state law.
What's missing: 2023, 2024, and 2025 data. HCD now collects ADU permit reporting at the state level via the Annual Progress Report (APR) framework; we expect a publishable 2023–2025 update from BuildinganADU.com or directly from HCD in 2026. We will republish this analysis when that arrives. Counties are excluded from the city-level analysis above (top 15, long-tail counts, grade-vs-volume) because their permit-issuing geographies differ in shape from incorporated cities; including them double-counts in metros where city and county both report.
Data files: this article was generated from `permits_ca.csv` (88,885 total rows of city × year × permits), `permits_ca_totals.csv` (525 places, lifetime ranking), and `cities_master.csv` (563 jurisdictions with tier, scorecard grade, and ordinance link). All three files live in the `data/` folder of the BackyardADU.net build pipeline; the analysis is reproducible from `python -c "from generators.articles import *; print(_load_year_totals())"`.
The Big West Coast ADU Dataset records 88,885 ADU permits issued by California cities and counties between 2013 and 2022. The dataset has not yet been updated with 2023–2025 data; we expect the update from HCD in 2026.
Los Angeles, by an enormous margin. LA permitted 27,125 ADUs from 2013 to 2022 — about 35% of all city-issued California ADU permits in that window. The next-largest city, San Diego, permitted 2,891.
Yes, on the metric they were designed to move. Statewide ADU permits jumped from 1,336 in 2016 to 5,154 in 2017 — a near-quadrupling — when SB 1069 and AB 2299 took effect. The 2019 follow-up package (SB 13, AB 68, AB 881) drove a further 42% year-over-year jump in 2019. Whether the resulting housing units are reaching the renters who most need them is a separate, harder question.
Three reasons. First, housing-stock incompatibility — many older or smaller cities lack convertible garages or have lot sizes too small for detached new-builds at $300+/sqft construction costs. Second, demographic mismatch — ADUs are disproportionately built by homeowners aged 55–75. Third, post-preemption knowledge gaps — many homeowners and city planning departments have not yet adjusted to the fact that state law overrides previously-restrictive local ordinances.
The 2021→2022 growth rate was 21% — well above the rate of housing-cost inflation and well above population growth. There is no sign of plateau in the public permit data. Whether 2023+ data confirms this depends on construction-cost trajectories and interest rates; financing has materially tightened since 2022.