Tracy, CA Accessory Structures: ADU Rules (2026)

3180 permits exactly one accessory dwelling unit on a residentially zoned lot that already has one single-family home, whether attached, detached, built by converting part of the primary dwelling or an accessory structure, or built as new construction. It is not available where the lot already carries more than one single-family dwelling, a duplex, or a multi-family building, and the unit can never be sold apart from the primary home. Size is capped by type: a detached ADU tops out at 1,200 square feet of living area, and an attached ADU is limited to 50 percent of the primary dwelling's living area or 1,200 square feet, whichever is smaller, counting interior habitable space but not a garage or accessory structure.

The ADU must otherwise meet the height, setback and lot-coverage rules of its zoning district, with two carve-outs: a unit built above a garage needs only a five-foot side and rear setback, and an existing garage converted into an ADU needs no setback at all. A minimum six-foot separation is required between the ADU and the primary dwelling or another accessory building, and the unit may have interior or exterior access. Parking is normally one additional off-street space per ADU, which can be tandem or located in a setback area, and if building the ADU means demolishing or converting a required garage or covered space, that lost parking must be replaced somewhere on the same lot.

However, no extra parking is required at all if the ADU sits within half a mile of a Tracy Tracer or San Joaquin RTD bus stop, is created entirely within the existing footprint of the primary dwelling or an existing accessory structure, or is within one block of a designated car-share pickup spot. 2.