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

Modoc County's published ADU information states plainly that an ADU 'cannot be Tiny Homes on Wheels, RVs, Yurts, or Storage Structures' and must have a minimum floor area of 150 square feet. ADUs may be of standard residential construction, manufactured housing or factory-built housing placed on permanent foundations, consistent with state ADU law and the California Building Code; a site-built tiny home meeting those codes can therefore be permitted as a permanent dwelling or ADU. For non-permanent units, Zoning Code Section 18.100.040 governs the temporary use of a mobilehome, manufactured home or recreational vehicle during construction of a dwelling, and Sections 18.100.050 and 18.100.060 address mobilehomes/manufactured homes used for residential purposes and recreational vehicles. These provisions generally allow a registered RV, mobilehome or travel trailer as a temporary residence while a permanent home is built under an active building permit, subject to removal once the permanent dwelling is occupied. A JADU, by contrast, must be no more than 500 square feet and contained entirely within an existing or proposed single-family residence, so it cannot be a standalone tiny structure. Because the County code cites state ADU law (Government Code 65852.1 and 65852.22, renumbered to Government Code 66310-66342 in 2024), the state minimums (such as the 150-square-foot floor and prohibition on movable units serving as permanent ADUs) apply alongside the County's standards.