Oakley, CA Accessory Structures: Tiny Homes (2026)

Tiny homes fall into three regulatory categories in California: (1) permanent foundation tiny houses built to the California Residential Code, which are treated as single-family dwellings or ADUs; (2) movable tiny houses built to ANSI A119.5 standards, which some cities allow as ADUs under AB 2533 or local ordinance; and (3) tiny homes on wheels (THOWs) registered with DMV as RVs, governed by Health & Safety Code sections on recreational vehicles. The California Residential Code was amended to allow efficiency/micro units with a minimum 150 sq ft living area plus a separate bathroom (previously 220 sq ft) when they meet ventilation, egress, and safety rules. Permanent tiny houses meeting code standards can serve as primary dwellings or as ADUs under Government Code Section 65852.2, qualifying for all state ADU streamlining. HCD-certified factory-built tiny homes (from registered manufacturers) can be installed on permanent foundations and permitted as ADUs with an expedited process. Movable tiny houses (MTH) built to ANSI A119.5 can be approved as ADUs where the local ordinance permits; some cities require wheels removed and connection to permanent utilities. THOWs registered as RVs generally cannot be used as permanent residences in most residential zones under California Vehicle Code and local zoning, though stays in approved RV parks are allowed. Oakley has not adopted a specific MTH ordinance; applicants should confirm current Planning Division policy. Required amenities for a permanent tiny-house ADU include a kitchen (sink, stove, refrigerator), a bathroom with toilet and shower, sleeping area (not required to be separate), heating, smoke and CO alarms, and compliance with energy (Title 24), electrical, plumbing, and fire-safety codes. Utility connections must meet PG&E and Diablo Water District standards.