Davis, CA Accessory Structures: ADU Rules (2026)

22, the state laws that require cities to approve accessory dwelling units without discretionary review when a project meets state and local standards, while still letting the city set reasonable limits on size, height, setbacks, and parking. Under subsection (e)(2), an attached ADU cannot exceed fifty percent of the primary dwelling's gross floor area, and a detached ADU is capped at eight hundred fifty square feet, rising to one thousand square feet if it includes more than one bedroom; no ADU may be smaller than two hundred twenty square feet or the state efficiency-unit minimum.

Height is limited to sixteen feet, except that an attached ADU may be built as a second story of the primary residence if it meets the zone's height and setback rules. Side and rear setbacks are four feet for most new ADUs, and none is required at all for an ADU built within an existing structure or rebuilt in the same footprint. Subsection (e)(2)(D) adds a favorable rule: an ADU of eight hundred square feet or less, no taller than sixteen feet, and meeting the four-foot side and rear setback is deemed consistent with the zoning district's lot coverage, floor area ratio, and open space limits regardless of what those limits would otherwise require.

No additional parking is required for a ministerial ADU, and none is required to replace a garage converted into one, as long as it remains in legal use as an ADU.