Tiny Homes in San Diego County, California
Last verified: October 21, 2026. San Diego has two different sets of rules: unincorporated County areas and the City of San Diego. Other cities (Carlsbad, Oceanside, Chula Vista, etc.) set their own rules; Zen's $500 site assessment checks what fits your lot.
Quick answer
Where | Unincorporated County | City of San Diego |
Backyard, foundation ADU | Yes (state ADU law) | Yes (state ADU law) |
Backyard, tiny home on wheels | Yes, as an accessory dwelling | Yes, as a "movable tiny house" |
Own land, THOW as the only home | Yes (since Sept 4, 2025) | No; it must be behind or beside a primary dwelling |
RV/mobilehome park | Park trailers allowed in parks; County THOW rules don't apply there | Park rules apply |
Unincorporated San Diego County (County PDS)
Since September 4, 2025, a THOW counts as a dwelling unit and can be a primary or accessory home if it meets these requirements:
Smaller than 430 sq ft, one floor, plus a loft up to 150 sq ft
No taller than 16 ft
Certified to ANSI A119.5 by an approved third-party agency. All Zen Tiny Homes are built to ANSI standards.
Noncombustible exterior walls and a fire-resistant roof; some homes need sprinklers
A PDS permit with two printed plan sets (11x17 minimum): scope, plot plan, the Director's Determination Letter, certification letter and stormwater forms
Possible extra reviews: fire access, legal lot, septic, flood, grading, stormwater, off-grid electrical, right-of-way
County inspections (plumbing, electrical, water, sewer, final) plus fire district sign-off. Certification is not a substitute for inspections.
On septic: the County's Environmental Health department has a THOW septic FAQ (DEH FAQ).
City of San Diego (SDMC §141.0318, IB 403)
A movable tiny house must:
Be DMV registered, one story, not self-propelled, and no bigger than state law allows on highways
Be certified to NFPA 1192 or ANSI A119.5, with a label
Sit behind or beside the main house (not in the front yard), 5 ft from side/rear lot lines and 10 ft from other structures
Be on a lot next to a street at least 20 ft wide, within 150 ft of it, with a 5-ft access path
Keep its wheels on, with the undercarriage hidden, on a paved surface
Connect to water, sewer and electric; no gas
Have sprinklers if the main house does, and meet extra rules in Very High Fire Hazard Severity Zones
Not be in a brush management zone or the MHPA habitat area. Coastal zone eligibility depended on Coastal Commission certification as of IB 403 (2020), so confirm current status with the City.
Money help
City of San Diego homeowners building a permanent ADU may qualify for the SDHC ADU Finance Program (up to $250,000 at 3% fixed, income limits apply) (SDHC).
Steps
Confirm whether your parcel is in the City, another city, or unincorporated County.
Check fire, brush and flood zones.
Book a site assessment (access path, setbacks, utilities, septic).
Choose a certified THOW or a foundation ADU.
Submit plans, pass inspections, keep DMV registration current.
Zen Tiny Homes is based in San Diego and builds for both City and County sites. A Site Assessment is $500.
Frequently asked questions
Are tiny homes on wheels legal in San Diego County?
Yes. Unincorporated County areas allow them as primary or accessory homes since September 4, 2025, and the City of San Diego allows movable tiny houses behind or beside a main house.
Can a tiny home be a primary home in unincorporated San Diego County?
Yes, if it is under 430 sq ft, certified to ANSI A119.5, meets the fire rules, and gets a PDS permit and inspections (County PDS).
Are there tiny home communities in San Diego?
A few in the county say publicly that they accept tiny homes, such as Tiny House Block in Mount Laguna and Basecamp Palomar in Pauma Valley. See our verified list.
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.
Beach House: 3D exterior
Beach House: floor plan
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.
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