How YIMBYs Helped Kick Off a California Building Boom
In 2016, California state policymakers established a statewide set of rules for legalizing accessory dwelling units (ADUs). Eight years later, and complemented by additional, follow-on ADU regulations, we can definitively say that this reform program has been an overwhelming success: YIMBY-supported ADU legalization has triggered a building boom, such that ADUs now comprise a large share of new housing produced in most cities.
The success of ADU legalization serves as a ready model, both for future land-use reforms in California and other states seeking to address the housing shortage.
The momentum behind accessory dwelling units in California is proof that there are many approaches we can take to solve the housing shortage and affordability crisis. I was proud to author AB 1332, which makes it faster and easier for homeowners to get approvals for ADUs, and builds on this momentum.
Assemblymember Juan Carrillo, Palmdale
What Has ADU Legalization Accomplished
The permitting data from the past eight years is unambiguous: ADU legalization triggered a building boom. According to permitting data compiled by HCD:
- The number of ADUs permitted each year in California increased by 15, 334% between 2016 and 2022, collectively resulting in 83, 865 ADUs permitted.
- Other than 2020—a year beset by the COVID-19 pandemic—ADU permitting has increased by 42 to 76% every year since 2016. There is little reason to believe that this growth in permitting will slow down any time soon.
- As of 2022, 19% of all housing units produced in California—or nearly one in five homes— is an ADU.
The success of our laws encouraging the development of Accessory Dwelling Units shows that progress is possible. I will continue to apply these lessons to new and existing laws so that we can be as successful in building other types of homes to make California more affordable and accessible for everyone.
Assemblymember David Alvarez, Chula Vista
ADU Webinar
On February 8, 2024 California YIMBY held a webinar on our report, featuring our Research Director Nolan Gray and Ryan O’Connell, founder of How to ADU. You can view the hour-long webinar here!
Download and read the full report here
Or read the full report online below
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