Tiny Homes in Santa Cruz County, California
Last verified: October 21, 2026. This covers unincorporated Santa Cruz County. Cities such as Santa Cruz, Watsonville, Capitola and Scotts Valley have their own rules.
Quick answer
Where | Allowed? |
Backyard, foundation ADU | Yes (state ADU law) |
Tiny home on wheels | Yes, with a County permit; one per parcel |
THOW as the primary home | Yes, but it then requires fire sprinklers |
THOW as an ADU | No. The County says THOWs may not be permitted as ADUs, following state HCD guidance |
Flood hazard area | No for THOWs |
All points below come from the County's Tiny Homes page and County Code §13.10.680 (Santa Cruz County CDI).
THOW rules
What it is: a park trailer under HSC §18009.3, built to ANSI A119.5 and certified by a qualified inspector
Size: max 400 sq ft; no taller than 14 ft
Permit: required, like any new house; the inspector checks the certification and the on-site installation
DMV: register every year. If registration lapses, the THOW permit expires
Water and sewer: connect to approved water and sewer or septic. A composting toilet cannot replace a compliant septic system
Power: utility or an off-grid system with solar and battery storage. Generator limits depend on location (urban/rural service lines)
Parking pad: not on a driveway; level and paved (2" asphalt over 5" Class II base rock, or equivalent); wheels stay on; seismic tie-downs if it's a permanent residence; may need a geologic review in hazard areas
Looks: house-like siding/roofing, pitched roof, eaves, residential windows and trim; wheels skirted; wildland-urban interface rules apply
Money help
HCD lists a Santa Cruz County ADU Forgivable Loan Program for owners who rent ADUs to low-income households (HCD ADU funding). Terms and funding can change. It applies to ADUs, and THOWs aren't ADUs here.
Steps
Confirm you're in unincorporated County, not in a flood hazard area.
Check geologic hazards and fire (WUI) status.
Plan the pad, septic/sewer, water and power.
Buy a certified ANSI A119.5 THOW with house-like design.
The permit goes through the County's THOW permit process; register with DMV every year.
Frequently asked questions
Can a THOW be an ADU in Santa Cruz County?
No. The County follows HCD guidance that THOWs may not be permitted as ADUs, but it permits them as their own unit, one per parcel (Santa Cruz County).
Does my THOW need DMV registration every year?
Yes. If the registration lapses, the THOW permit expires.
Can I use a composting toilet instead of septic?
No. The County does not accept a composting toilet in place of a compliant sewer or septic system.
Related guides
Floor Plan Preview
Here's a look at two of the designs Zen Tiny Homes can build. Every plan can be adjusted to fit your lot.
Mammoth: floor plan
Mammoth: 3D section views
See all the layouts in California Tiny Home Floor Plans.
Ready to plan your tiny home?
Zen Tiny Homes in San Diego designs and builds tiny homes (Alpine, Mammoth, Container, and fully custom). Fill out the free Buyers Application and we'll help you choose the right path for your site and budget.
Prefer to talk? Call Zen Tiny Homes at 760-492-0742 or visit zentinyhomes.com.
This guide is general information, not legal advice. Rules change. Zen's $500 site assessment checks what fits your lot, or call 760-492-0742.
Inside Santa Cruz city limits? Read Backyard Tiny Homes in the City of Santa Cruz.
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