California ADU Statistics (2026): Permits by Year, County & City

California ADU permits by year, 2018–2025

The statewide trend is unambiguous: ADU permits have grown every single year since reporting began, from 8,992 in 2018 to 41,634 in 2025 — a 4.6× increase. Just as telling is the share: in 2021 ADUs were 15.5% of all new homes permitted in California; by 2025 they were 25.9% — one of every four new homes in the state is now an ADU.

Source: California HCD, Annual Progress Report Table A2 (units with building permits issued), queried August 2026.

The counties building the most ADUs (2025)

Southern California dominates: Los Angeles County alone accounts for nearly half of every ADU permitted in the state, and Los Angeles, Orange and Riverside counties together account for 58% of California’s 2025 ADU permits — which is exactly the territory we build in.

Top seven counties by 2025 ADU building permits, same source as above.

Orange County: ADU permits by city

Orange County’s ADU count grew from just 297 permits in 2018 to 2,856 in 2025 — nearly a tenfold increase — and ADUs are now about one of every three new homes permitted in the county. The north-county flatland cities lead: Fullerton, Anaheim and Garden Grove between them issued more than half of the county’s 2025 total.

Top 15 Orange County jurisdictions by 2025 ADU permits, as reported to HCD by each city. A few cities’ most recent filings appear incomplete in the state dataset; figures reflect what each jurisdiction reported.

Los Angeles & Inland Empire cities we serve (2025)

The City of Los Angeles is the single largest ADU market in America — 12,328 permits in 2025, more than every other California county combined outside LA. Around it, the mid-size cities we build in each permit hundreds a year.

Same source and metric as above; jurisdiction-reported.

What the numbers mean if you own a home here

This surge is not fashion — it is law working as designed. California guarantees ministerial approval for an ADU of up to 800 sq ft on qualifying lots, gives cities 15 business days to check completeness and 60 days to decide, and exempts units under 750 sq ft from development impact fees. The result is the fastest-growing housing type in the state — and in Orange County, where published rents for ADUs run $1,800–$4,000 a month, the investment case explains the curve. See what building one costs in our 2026 cost guide, browse 400, 500, 800 and 1,200 sq ft builds by size, or check the rules in your city.