Why California rewrote the ADU rulebook
California has the worst housing shortage in the country, and ADUs are one of the few tools that add housing without changing neighborhood character. Beginning in 2017 and accelerating every legislative session since, the state has passed a series of laws (SB 9, SB 1211, AB 2221, AB 1033, and many more) that strip away local barriers and create ministerial approval pathways for compliant projects.
What state law guarantees you
Up to one ADU and one JADU per single-family lot — sometimes more. Minimum 4-foot side and rear setbacks for ADUs up to 16 feet tall. No minimum lot size requirement. No off-street parking required within a half-mile of major transit. 60-day ministerial review for compliant plans. No owner-occupancy requirement for ADUs (JADUs still require it).
What cities can still do
Cities can set objective design standards (materials, height, lot coverage), require fire-safety upgrades, and impose impact fees on units over 750 square feet. They cannot impose discretionary review on compliant ADU applications, and they cannot enforce older local restrictions that conflict with state law.
How to use the law to your advantage
Design your ADU to fit the state ministerial pathway and you'll skip the most expensive part of permitting — discretionary review and public hearings. An experienced design-build team will know exactly where state law gives you leverage and where local rules still apply.