Originally published October 2022.

In the United States, zoning laws are overwhelmingly local concerns, though heavily influenced by federal pressures, like lending and highway construction. So it’s somewhat novel that the California legislature has passed a series of seven (and counting) statewide bills explicitly to allow the construction of auxiliary dwelling units (ADUs), dismantling a brick wall of state and local restrictions. 

Bureaucratically named ‘Auxillary Dwelling Units’ are creative housing arrangements familiar nationwide, encompassing the basement apartment, granny flat, in-law suite, carriage house and the rentable room above the garage, among others. In the tradition of middle-income families taking on boarders, property owners happily share their spaces in exchange for help paying the mortgage. Renters get good prices (usually paying less than in a commercial apartment building) and live in an area which might otherwise be out of reach. For young people starting out, those starting over and older people downsizing, these shared residential situations offer significant benefits.

For 100 years it was functionally illegal to build a seperate, rentable space on your own property in California. In the moralistic zoning frenzy of the past century, California led the way on restricting land use, favouring single-family lots of minimum acreage and forbidding the construction of higher-density, usually more affordable, housing. In a recent reversal, a 2016 California Assembly bill explicitly authorised new ADUs and required local governments to issue building permits accordingly. 

Since then, Californians have voluntarily built at least 35,000 additional housing units and received permits for 20,000 more. In a state where 80% of new housing is classified as ‘above moderate income’, ADUs seem to be going in exactly the opposite direction. A government-led affordability analysis found 66% of newly constructed units were affordable to low-income renters.