Los Angeles County’s backyard-housing boom is showing no signs of slowing as accessory dwelling unit construction reached an all-time high last year.
The county completed 10,230 ADUs in 2025, more than six times the 1,624 completed in 2018, the Los Angeles Daily News reported, citing a new report from the University of Southern California’s Lusk Center for Real Estate. ADUs made up 37.5 percent of the 27,293 housing units certified for occupancy last year, marking the highest share on record in the near-decade that USC has been tracking ADU production.
The surge came even as overall housing production dipped from 28,498 units in 2024. Teardown activity also jumped, partly because of the Palisades and Eaton fires, meaning some of the county’s new housing represented replacement units rather than net additions.
USC researchers credited state and local policies that streamlined ADU approvals and loosened development restrictions with the spike in construction of so-called granny flats. In the city of Los Angeles, ADUs moved from permit to completion in about 18 months on average, compared with roughly three years for projects with five or more units.
That speed is significant in a region facing a massive housing shortfall. L.A. County jurisdictions are expected to plan for roughly 812,000 new homes during the state’s 2021-29 housing cycle. As of the beginning of this year, only about 125,000 had been completed.
“Even if the trend is moving in the right direction, the scale of the gap between where we are and where we need to be in terms of the regional goals is so vast that the ADU impact is ultimately a drop in the bucket,” Jared Schachner, the report’s research director, said.
While ADUs contributed the most to the overall new housing supply, not every ADU functions like a conventional rental. Some house property owners’ relatives or friends, while others may be rented seasonally or remain vacant. That could limit the boom’s impact on the open-market
rental supply.
About 19 percent of new rental units completed in 2025 were affordable to low-income households, nearly twice the average share of the previous seven years. Still, 57 percent of county renters were rent-burdened in 2024 and 30 percent were severely rent-burdened, spending more than half their income on housing.