Tiny Homes: Berkeley vs Sunol

Can I park my tiny home on wheels in my Berkeley backyard?

Not for full-time dwelling. THOWs are RVs under California law and cannot be used as permanent residences on residential property. Short-term storage may be allowed with setback compliance.

Do tiny homes on foundation need full foundations?

Yes. To qualify as an ADU, the tiny home must sit on a permanent engineered foundation (slab or pier) meeting CRC. Skirted trailer setups do not qualify.

Can I put a tiny house on wheels in my backyard in unincorporated Alameda County?

California HCD treats tiny houses on wheels as recreational vehicles under ANSI A119.5 standards, not as dwelling units. Alameda County has not published an unincorporated ordinance that authorizes a movable tiny house as a permanent residence the way some California cities have. Confirm with the Alameda County Planning Department at (510) 670-5400 before siting a unit.

What size ADU does Alameda County allow on an unincorporated lot?

Chapter 17.55 of Title 17, adopted by Ordinance O-2024-32, implements California Government Code Section 65852.2. ADUs up to 1,200 square feet are generally available by-right, with a 4-foot side and rear setback minimum for new detached units. Junior ADUs are limited to 500 square feet under Government Code Section 65852.22 and require an owner-occupied R-1 lot.

Does Alameda County allow a tiny house on a permanent foundation?

Yes, when permitted as an Accessory Dwelling Unit under Chapter 17.55. A small foundation-based tiny home of 400 square feet or less can be designed under California Residential Code Appendix Q, which sets specific lofts, ladders, and ceiling-height standards for tiny houses. The unit must still meet ADU setbacks, height, and design standards under Chapter 17.55.