California officials and housing advocates have portrayed accessory dwelling units as a much-needed component of the supply of new homes.
In some parts of the Bay Area, they’re all that’s coming.
Out of the 58 homes permitted last year in the wealthy town of Hillsborough, for example, 56 were ADUs — 97%, the seventh highest share in California among jurisdictions with at least 50 newly approved homes. In the uber-expensive enclave of Atherton, 45 of the 60 green-lit homes were ADUs. That’s according to data reported by those cities to the California Department of Housing and Community Development.
Thanks to a slate of state streamlining laws passed over the last decade, building an ADU has become one of the easiest ways for property owners to add an extra home on their lot. That’s made them relatively popular even in suburban cities that have resisted densifying their neighborhoods, especially because jurisdictions can count such units toward their state-mandated housing goals. For example, all of the newly permitted homes Mountain View and Santa Clara reported last year as being affordable to low-income residents were ADUs…