If you’re looking at turning your garage into living space, you’ve probably run into the terms JADU and ADU. Picking between a junior ADU and a full ADU is a central decision for many San Diego homeowners. Understanding the rules, benefits, and limits is the first step to making your project a reality.
What’s the difference between a JADU and a full ADU?
In California and San Diego, both ADUs (Accessory Dwelling Units) and JADUs (Junior Accessory Dwelling Units) allow you to create a new living space. They’re not the same, though. Each has distinct requirements and possibilities under local and state law.
A full ADU is an independent living unit. It has a kitchen, bathroom, separate entrance, and complete living facilities. ADUs can be created by converting a garage—attached or detached—or by building new space. In San Diego, detached garages and attached garages can both become full ADUs if they meet zoning and building codes. A full ADU typically allows more space, a dedicated bathroom, and flexibility with utility hookups.
A JADU is a smaller, more limited option. JADUs are carved out from space that is already inside, or attached to, the main house. State law makes one important allowance: for JADU purposes, an attached garage counts as part of the house, so converting an attached garage to a JADU is possible. Detached garages can’t become JADUs—they can only be full ADUs. JADUs are limited in size: the City of San Diego sets the range from 150 to 500 square feet. JADUs require an “efficiency kitchen” and a separate entrance, but unlike an ADU, a separate bathroom isn’t required—they can share the bathroom in the main home.
The main rules come from California law (see Gov. Code §66333) and the City of San Diego ADU page. Always confirm with your city, as local zoning can further shape what’s allowed.
When is a garage JADU conversion possible in San Diego?
The City of San Diego, and California law statewide, require a JADU to be “constructed within the walls of the proposed or existing single-family residence.” Here, an attached garage is considered part of those “walls”—so if your garage shares a wall with your house, you likely can convert it to a JADU.
If your garage is detached, even if it sits right next to your house, it’s not within the main house walls. In that case, a JADU conversion is not allowed—your option is a full ADU instead.
A few specifics you’ll need for an attached garage JADU in San Diego:
- Separate entrance: The JADU must have its own exterior door, often created by replacing the garage door with a secure, code-compliant entry.
- Efficiency kitchen: A JADU must have a kitchen setup with appliances, a prep counter, and reasonable storage—think compact, but “real” cooking is possible.
- Size limit: 150–500 sq ft is the range set by the City of San Diego. The available square footage in most attached garages fits.
- Bathroom: A JADU may—but does not have to—include its own bathroom. If you don’t, the JADU shares the existing home’s plumbing and facilities.
- Owner-occupancy: If your JADU shares sanitation with the main house, you’ll need to live on the property (in either the main home or the JADU). If the JADU has its own bathroom, owner-occupancy is not required.
You’ll need city permits, and your space must be brought up to all current building, safety, fire, and energy codes. Each city, including San Diego, will want to see plans for the conversion and check that your lot, setbacks, parking, and structure qualify before giving the green light.
Read through the city’s official ADU guide and talk to San Diego Development Services before you proceed.
Pros and cons of JADU vs. ADU for local homes
Choosing between converting your garage into a JADU or a full ADU comes down to your lot, goals, and the rules where you live.
JADU Pros:
- Easier utility connections: JADUs share utility connections and, if sharing a bathroom, plumbing. This can simplify the construction part.
- Lower permit hurdles: Some cities streamline JADU reviews, as the size and scope is smaller and impacts on parking/traffic are lower.
- Fits smaller budgets and needs: If your goal is extra living space for a family member or home office, and you don’t need a full kitchen or bathroom, a JADU can be ideal.
- Owner stays on site: For properties where you want flexibility but aren’t aiming to rent out a separate unit long-term, JADUs can fill the gap.
JADU Cons:
- Space is limited: That 500 sq ft maximum, plus the attached-garage requirement, means you’re not adding a large or free-standing unit.
- Owner occupancy may be required: If your JADU shares a bathroom, you must live in the main house or the JADU itself.
- No separate utility meters: If you want fully separate billing or utility shutoff, a JADU doesn’t provide that (unless built with certain upgrades).
Full ADU Pros:
- Maximum flexibility: Full ADUs are independent homes. You can rent them out for longer stays (subject to the city’s rental rules), house relatives, or create a fully separate rental.
- Eligible in both attached and detached garages: Even a detached garage at the back of the lot qualifies for a full ADU.
- Larger size and amenities: Full bathrooms, larger kitchens, in-unit laundry, and outdoor access are all possible.
Full ADU Cons:
- More work: Full ADUs require separate plumbing, their own bathroom, and a kitchen—all to current code.
- Utility upgrades: You may need new meters and connections, especially if the structure is detached.
- Permit reviews can be more involved: The city will check for parking impacts, setbacks, fire access, and often requires detailed site plans.
- Construction time and scope: Expanding the building envelope, adding new walls, or digging for new plumbing increases both complexity and time.
Both options bring a garage up to full residential living standards. That means the pros you’re matched with will review insulation, moisture barriers, heating and cooling, window egress, and electrical load, no matter which path you take.
How to choose the right option for your property
Start with your garage layout and what you actually want from the new space.
Attached garage and want a compact in-law suite or home office? A junior ADU conversion may be your best fit. The process is generally faster—there’s less utility work, and you might skip building a new bathroom if access to the main house works. But you’ll need to meet the city’s entry, kitchen, and size standards, and if your JADU shares facilities, owner-occupancy will apply.
Detached garage or seeking a full rental or live-in unit? Go for a full ADU conversion. This unlocks a wider range of layouts, privacy, and rental flexibility. Detaching from the main house also means a bigger scope—think new water and sewer lines, more robust HVAC, and separate bathroom and kitchen facilities.
Review your property’s zoning. The City of San Diego’s ADU/JADU program page maps out exactly what’s allowed by neighborhood and overlay zone. For other cities in San Diego County, check the ADU resources on your city website and call your city’s planning department if needed.
Budget, timeline, and goals: Without naming prices, it’s safe to say a JADU conversion is usually a smaller investment in both cash and time but offers less flexibility. A full ADU will cost and take more but brings broader uses. Zoning, your lot, and your long-term plans should shape your pick.
Finally, always work with a licensed contractor or pro who specializes in local code and permit requirements. You can check licenses directly at cslb.ca.gov to confirm the pro you’re working with is properly qualified for this kind of project.
When to call us
If you’re deciding between JADU and ADU garage conversion, permit requirements, and what’s possible on your lot, it’s time to bring in a licensed local ADU pro. Call (858) 400-4662, leave a message with your address and what you’re planning, and we’ll connect you with a licensed local ADU contractor.