San Joaquin County, CA Accessory Structures: Tiny Homes (2026)

San Joaquin County treats tiny homes under three distinct legal frameworks. (1) Foundation-built tiny homes are regulated as single-family dwellings or Accessory Dwelling Units under California Government Code §65852.2 (ADU law). State law preempts local minimum square-footage requirements for ADUs — cities and the county cannot mandate a minimum size above 150 sq ft (HCD ADU Handbook). ADUs may be up to 1,200 sq ft detached (AB 2221 / AB 976) with 4-foot side/rear setbacks and no owner-occupancy requirement through 2025 sunset. California Residential Code Appendix Q provides building standards specifically for dwellings 400 sq ft or less, including smaller stair rise, smaller egress windows, and lofts. (2) Tiny Homes on Wheels (THOW) are classified as either recreational vehicles under CA Vehicle Code §18010 or park-model RVs under HSC §18009.3. Full-time occupancy of a THOW on a residential lot is prohibited across San Joaquin County jurisdictions except in licensed RV parks or mobile home parks. (3) Manufactured tiny homes meeting HUD Code can be sited as manufactured homes under HSC §18000 et seq. in zones allowing mobile homes. Stockton, Lodi, and Manteca have all updated their ADU ordinances to comply with Gov. Code §65852.2 streamlined review — 60-day approval deadline, ministerial approval, no owner-occupancy. Utility connections, septic (if no sewer), and foundation per CRC required.