Santa Cruz County, CA Accessory Structures: Tiny Homes (2026)

Santa Cruz County adopted a Tiny Homes on Wheels ordinance (Ordinance 5413, adding County Code Section 13.10.680, certified by the California Coastal Commission in 2023) that lets THOWs be permitted as permanent single-family dwellings in unincorporated areas. A THOW is defined as an independent dwelling unit built on a single chassis, towable by a hitch, that cannot move under its own power, with a maximum size of 400 square feet. Only one THOW is allowed per parcel, and it may serve as either the primary unit or an accessory unit, provided the parcel's total dwelling-unit count is not exceeded. Importantly, because a THOW is legally a vehicle registered with the DMV, the County (following state HCD guidance) does not permit THOWs as accessory dwelling units (ADUs), which must be permanent buildings. THOWs must be built to the ANSI A119.5 Park Model RV standard with third-party certification. The County permit must be renewed every five years, the unit must be registered annually with the DMV with all fees paid (failure to register causes the permit to expire), and the unit must be placed on a level parking pad (two inches of asphalt concrete over five inches of Class II base rock) with wheels remaining installed and seismic tiedowns as required for mobile homes; THOWs cannot be located on driveways. Geologic-hazard review under County Code Chapter 16.10 may apply. Separately, traditional tiny houses on permanent foundations are regulated as ADUs or dwellings under the standard zoning and building rules.