ADUs may do little for housing

Backyard units are booming. Here’s why that’s not enough to ease the state’s crisis.

- TERRY CASTLEMAN

ADU PRODUCTION in California was up 14.3% in 2024 over the previous year.

With California facing a critical housing shortage, accessory dwelling units now account for a significant portion of the state’s meager growth in new homes, data reviewed by The Times show.

California has struggled to keep up with demand, increasing housing stock by only 0.84% in 2024, or 125,000 units. ADUs made up about one-fifth of those units, according to California Department of Finance data.

ADU construction has been booming in some parts of California, with homeowners taking advantage of the opportunity to build a second housing unit in their backyard. The units often cost hundreds of thousands of dollars, but many residents see them as worthy investments that increase property value.

But ADUs are different from new apartments and homes. Some ADU owners do not put their units on the market, using them instead for their own families or leaving them vacant. And ADUs are more popular in some areas than others.

Eric McGhee, a senior fellow at the Public Policy Institute of California, said it’s hard to know whether new ADUs are being used to house people who wouldn't otherwise be on the property, or whether they are just providing extra space for those already living there. As a result, it is likely that some ADUs do nothing to ease the housing shortage.