Every California city publishes its own zoning code, and most still contain ADU rules that contradict state law. The state wins. Cyrus Poudat keeps a one-page cheat sheet of state-law ADU minimums in his bag because plan checkers occasionally need a polite reminder of which code applies.
The 4-foot setback
California state law caps side and rear setbacks for ADUs at 4 feet. Cyrus Poudat regularly invokes this when California building departments ask for 5 or 10. The rule applies whether the ADU is new construction or a conversion.
Height limits
State law allows at least 16 feet, often 18 feet, and up to 25 feet near a major transit stop. Cyrus Poudat designs California ADUs to the maximum allowed height when site lines and shading impacts allow it — that extra story dramatically increases value and rentability.
Lot coverage and FAR
California cities cannot enforce lot coverage, FAR or open-space rules that would prevent at least an 800 sq ft ADU. Cyrus Poudat invokes this protection on tight California lots where the existing home already approaches the lot coverage limit.
Front setback
Front setbacks still apply. Cyrus Poudat works with California clients to use detached rear-yard placement to sidestep the issue entirely, and uses attached side-of-house additions only when the rear yard is unusable.
Distance from main house
Cities cannot require more than 4 feet between the ADU and the main house. Cyrus Poudat uses this on small California lots to place the ADU close to the existing structure and preserve usable yard area.
Maximum unit size
The state guarantees at least 850 sq ft for studios/1-bed and 1,000 sq ft for 2-bed ADUs. California cities can allow more, and Cyrus Poudat checks every local code for an upside before defaulting to state minimums.
When local rules apply
Local zoning still controls things state law does not preempt: architectural review in historic districts, design guidelines for front-facing additions, and certain coastal commission overlays. Cyrus Poudat flags these on every California feasibility review.