In 2016, San Francisco expanded its law allowing property owners to add accessory dwelling units (ADUs), to their homes, so that any building with at least five existing apartments could add an unlimited number of units.
With the median home value in San Francisco reaching over $1 million, "granny flats" may help property owners pay off expensive mortgages, and allows families to create more affordable housing options for extended family members, like aging parents, per CNBC. "There are now 1,046 ADUs in the pipeline, with building permits approved for 531 of them," according to the San Francisco Chronicle.
"The new laws won't come close to filling the Bay Area's housing needs. But they could create options for middle-income renters who don't qualify for below-market-rate housing and can't afford a market-rate apartment," the San Francisco Chronicle reported in late 2016 as the law was about to take effect.