When it comes to building more of the housing that California needs, the legislative reforms making it easier to build accessory dwelling units have been a major success story: In 2023, one in every five new homes built in the state was an ADU, resulting in 22,802 new homes.
But there is much wider interest in ADUs than that number suggests; it only represents legally permitted and constructed ADUs. New evidence shows that even with new streamlined permitting for these “mother-in-law cottages,” hundreds of homeowners are still building them illegally.