OC Register: One of Every 5 New Homes Built in CA Last Year Was An ADU
... In recent years, the state of California has seen an explosion in ADUs, also known as mother-in-law units or backyard cottages. In 2023, one out of every five homes built in the state was an ADU, according to recently released state data. Only three years ago, they represented just one in every 10 new units.