Siskiyou County, CA Accessory Structures: Tiny Homes (2026)

Siskiyou County does not regulate tiny homes as a distinct land-use category. A tiny house built on a permanent foundation is treated as an Accessory Dwelling Unit under the county's Second Unit Housing provisions in Zoning Code Section 10-6.1515, which the county administers consistent with California ADU law (Government Code 66310-66342). To accelerate small-home projects, Siskiyou County publishes free pre-approved building plans; the county's Pre-Approved Plans FAQ states all of the offered plans except the 3-bedroom/2.5-bath plan can be used as an ADU, and these plans are available throughout the county. A tiny home on wheels (THOW) or recreational vehicle is a different matter: under California Health and Safety Code Sections 18007 and 18008, such units are classified as recreational vehicles or, when factory-built on a chassis, as manufactured housing, and they cannot be used as a full-time residence on a parcel outside a permitted mobilehome or RV park. A factory-built or manufactured home placed on a permanent foundation, however, can serve as an ADU. Because tiny homes on rural parcels rely on private wells and septic, the county requires owners with an existing home to confirm adequate well and septic capacity with Environmental Health before adding a unit.