San Diego County Now Allows Tiny Homes on Wheels: What the 2025 Rule Means
Updated: 14 hours ago
For years, a tiny home on wheels in unincorporated San Diego County lived in a gray area. That changed on September 4, 2025. The County's Planning & Development Services department issued a Director's Determination confirming that a tiny home on wheels (THOW) built to ANSI standards can count as a dwelling under the zoning ordinance.
In plain terms, a qualifying tiny home on wheels can now be the main home on a lot, or an accessory dwelling unit (ADU) next to an existing house. The County's own news release called it a significant shift for local housing.
WHAT CHANGED IN SEPTEMBER 2025
Before the ruling, most tiny homes on wheels were treated like recreational vehicles, which are not meant to be lived in full time on a private lot. The new determination says a THOW that meets the right standards fits the County's definition of a dwelling without any change to the zoning code.
A qualifying THOW can be used as a primary home or an accessory home.
It does not change how many homes are allowed on a lot. Density and General Plan rules still apply.
The home has to sit on a private lot and cannot encroach into the County road right-of-way.
It applies to unincorporated areas such as Ramona, Alpine, Valley Center, Fallbrook and Lakeside. Cities like San Diego, Carlsbad and Oceanside have their own rules.
THE KEY REQUIREMENTS AT A GLANCE
The County's Tiny Homes on Wheels page lists the basics. A THOW must:
Be smaller than 430 square feet, with one floor plus an optional loft of up to 150 square feet.
Be no taller than 16 feet.
Meet ANSI standards and the County's added safety requirements.
Have noncombustible exterior walls and a fire-resistant roof. Some homes also need fire sprinklers.
Installing the home takes a County permit and a set of plans, and the site may need reviews for things like fire access, septic, grading, stormwater and off-grid electrical. After the permit, there are inspections for the utility hookups and a final inspection before you can move in.
WHAT ABOUT RV PARKS?
The County is clear that these THOW rules do not apply to park trailers in mobile home parks or RV parks. Those are treated as recreational or seasonal units, which is a different path with different rules.
WHY THIS MATTERS IF YOU ARE SHOPPING FOR A TINY HOME
This rule turns a tiny home on wheels into a much more practical option for County landowners. A few ways buyers are using it:
Backyard home for family. Add a THOW next to your house for a parent, an adult child or a caregiver.
Primary home on raw land. Live on a rural parcel in a small home instead of building a full-size house.
Rental income. An accessory home can create long-term rental income, subject to the local rules for your lot.
The catch is that the build has to be done right from day one. Wall materials, roofing, sprinklers, height and size all need to line up with the County requirements before the home ever leaves the shop.
HOW ZEN TINY HOMES HELPS
Every Zen tiny home on wheels is built to ANSI standards, and we design each one around where it will live. For County projects, that means planning the exterior materials, roof, loft, height and utility connections around the THOW requirements from the start.
Site assessment. We look at your lot, access, utilities and setbacks before you commit. Learn more on our Programs page.
Models built for real life. See the Alpine, Mammoth and Container homes and ask about custom builds.
Simple start. A deposit holds your spot for any product or service.
Pricing depends on the build, including size, layout, finishes and your site. Every model, from a 20-foot tiny home on wheels to larger homes, is quoted custom.
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READY TO TAKE THE NEXT STEP?
The fastest way to get a real answer for your project is to fill out our free Buyers Application. Tell us about your property, your timeline and the home you have in mind, and we will follow up with next steps.
Prefer to talk it through? Call Zen Tiny Homes at 760-492-0742.
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