Placer County, CA Accessory Structures: ADU Rules (2026)

Placer County's ADU ordinance was last updated in 2020 to align with California Government Code §65852.2 and §65852.22. Under Placer County Code 17.56.200 (and the related 17.56.095 / 17.56.180), every parcel zoned residential may have one primary dwelling, one ADU, and one JADU — up to three units total. Detached ADUs are capped at 1,200 sq ft. Attached ADUs may be the greater of 50% of the primary dwelling area or an 800 sq ft state-floor minimum (with a 1,200 sq ft maximum where the County permits). JADUs are capped at 500 sq ft, must be created within the existing walls of the primary single-family dwelling (or an attached garage), and require owner-occupancy of either the primary or the JADU per PCC 17.56.200.F. Side and rear setbacks are 4 feet for new detached ADUs. ADU applications are processed ministerially without a public hearing within statutory timeframes. Impact fees are waived for ADUs under 500 sq ft, waived (except school fees) for ADUs under 750 sq ft, and proportional for larger ADUs. ADUs permitted on or after Jan 1, 2020 carry a state-law deed restriction prohibiting rentals shorter than 30 days.