ADUs Offer Affordable Housing in California, but Challenges Persist

California needs to boost its housing stock, and advocates say accessory dwelling units are one useful strategy for adding affordable housing units while also providing homeowners with a source of income. John King writes that ADU supporters say the construction could significantly increase the amount of available housing:

CASA, a Bay Area-wide alliance of government, civic and business leaders organized by the Metropolitan Transportation Commission, makes the case that as many as 300,000 of the units could be added to the Bay Area without a noticeable increase in density. This would be a big chunk of the 525,000 housing units that CASA — a sort-of acronym for the Committee to House the Bay Area — says the region needs to build during the next 15 years.

State legislation passed in 2017 made ADU construction easier by easing requirements such as mandated off-street parking. Other state bills in the pipeline would lower impact fees and eliminate minimum lot sizes, and cities and counties throughout the state have also taken steps to streamline the process.

Still, many homeowners say taking on an ADU project often remains a costly and complicated endeavor. And in Portland, Oregon, which has been a leader in promoting ADUs, a huge increase in construction was followed by a leveling off. "This doesn’t mean that new backyard cottages or converted garages aren’t of value. We just shouldn’t ask them to do too much," says King.