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

San Bernardino County treats tiny homes differently based on whether they are movable or permanent. Tiny homes on wheels (THOWs) are classified as recreational vehicles under Vehicle Code 18010 and cannot be occupied as permanent residences outside of licensed RV parks or mobile home parks. Tiny houses on permanent foundations must meet the full California Residential Code including minimum room sizes, egress windows, smoke alarms, and energy efficiency (Title 24). California adopted Appendix Q to the Residential Code allowing dwellings under 400 sq ft with reduced ceiling heights (6 ft 8 in), loft rules, and ladder access provisions. These units are most commonly permitted as Accessory Dwelling Units under state ADU law (Government Code 65852.2), which preempts most local restrictions on minimum sizes. Foundations, sewer or septic connections, potable water supply, and electrical service are required. Unincorporated San Bernardino County communities have specific zoning considerations for parcels with septic systems. Contact the Land Use Services Department at (909) 387-8311 for site-specific guidance and the Building and Safety Division for plan check submittals.