Putting a Tiny Home in Your Backyard in California (ADU & JADU Rules)
A backyard is the most common place for a tiny home in California. The path depends on whether the home is on a foundation (ADU) or on wheels (local rules only).
Option 1: Foundation tiny home as an ADU
State ADU law gives homeowners strong rights. Per HCD's ADU Handbook (updated March 2026) (PDF):
One detached new ADU is allowed on a lot with an existing or proposed single-family home, up to 800 sq ft with 4-ft side and rear setbacks, and a height limit of 16, 18 or 20 ft depending on conditions (Gov. Code §66323).
Local rules cannot block an ADU of at least 800 sq ft with 4-ft side/rear setbacks (Gov. Code §66321).
A local maximum size must still allow at least 850 sq ft (or 1,000 sq ft with more than one bedroom).
No impact fees on an ADU of 750 sq ft or less of interior livable space; bigger ADUs pay fees proportionally (Gov. Code §66311.5).
No owner-occupancy requirement for ADUs.
The city/county must say whether your application is complete within 15 business days, and an ADU application not acted on within 60 days of being complete is deemed approved (Gov. Code §66317).
Many tiny homes are far under 750 sq ft, so a foundation tiny home ADU is usually impact-fee free. Permit and plan-check fees still apply and vary by city.
Option 2: JADU (inside your house)
A Junior ADU is no more than 500 sq ft and built inside the existing home (an attached garage counts). Since January 1, 2026 (HCD addendum):
Owner-occupancy is required only if the JADU shares a bathroom with the main house.
JADUs can't be short-term rentals; any rental must be longer than 30 days.
A JADU is a conversion, not a separate tiny home, but it is often part of the same plan.
Option 3: Tiny home on wheels in the backyard
State ADU law generally does not treat a THOW as an ADU (HCD, 2025). You need a local ordinance that allows it. Examples:
City of San Diego: movable tiny houses allowed behind or beside the main house, with hookups and certification (SDMC §141.0318).
County of San Diego (unincorporated): THOWs can be a primary or accessory dwelling since Sept 4, 2025 (County PDS).
City of Los Angeles, Santa Cruz County, City of Fresno: see county guides.
If your city has no THOW ordinance, plan on a foundation ADU instead.
Steps
Confirm your zoning and whether you're in a fire, flood or coastal zone.
Pick the type: foundation ADU, JADU, or THOW (only if allowed).
Get a site assessment for placement, utilities and access.
Prepare plans and submit; track the 15-business-day completeness notice.
Build or deliver, pass inspections, get final sign-off.
Frequently asked questions
Is it legal to put a tiny house in your backyard in California?
Yes, as a foundation ADU on a lot with a single-family home, under state ADU law. A tiny home on wheels needs a local ordinance that allows it.
How small can an ADU be in California?
State law lets an ADU be as small as an efficiency unit, which can be 150 sq ft (HCD ADU Handbook).
What is the maximum size of a JADU?
500 sq ft, built inside the existing home (an attached garage counts).
JADU vs ADU: what's the difference?
A JADU is a conversion of up to 500 sq ft inside your house. An ADU can be detached, like a tiny home on a foundation.
Do I pay impact fees on a small ADU?
No impact fees apply to an ADU of 750 sq ft or less of interior living space (HCD ADU Handbook). Permit and plan-check fees still apply.
Can I rent out a backyard tiny home?
State law has no owner-occupancy requirement for ADUs, so long-term rental is generally allowed. JADUs can't be short-term rentals, and your city may have its own short-term rental rules.
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.
Jamul Bungalow: 3D exterior
Jamul Bungalow: 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.
Comments