Buying Guide
JADU vs. ADU: What's the Difference? (California)
The short difference: a JADU (Junior ADU) is a small unit, up to 500 square feet, created within the walls of your existing house, while a standard ADU is a larger, fully independent home (up to 1,200 square feet) that can be detached in your yard. A JADU is a conversion of space you already have; an ADU is a new home.
For most people building a backyard rental or housing a parent, a detached ADU is the better fit, it’s a real, separate home with its own everything. A JADU makes sense when you want the cheapest possible path and have a spare bedroom to convert.
The short version: JADU = up to 500 sq ft carved out of your existing house, with owner-occupancy required. ADU = up to 1,200 sq ft, can be detached, fully independent, no owner-occupancy requirement. Most backyard builds are detached ADUs.
Side by side
| JADU (Junior ADU) | Detached ADU | |
|---|---|---|
| Max size | 500 sq ft | 1,200 sq ft |
| Location | Within the existing home’s walls | Standalone in the yard |
| Kitchen | Efficiency kitchen allowed | Full kitchen |
| Bathroom | Can share with main house | Its own |
| Owner-occupancy | Required (you live in one unit) | Not required |
| Entrance | Own exterior entrance | Own everything |
| Typical use | Convert a bedroom; light rental | Rental income, in-laws, primary-quality living |
When a JADU is the right call
A JADU shines when budget is the top priority and you already have the space, say, a bedroom with its own entrance you can convert. Because it reuses existing walls, it’s the lowest-cost way to add a rentable or family unit. The trade-offs: it’s small, it requires you to live on the property, and it may share a bathroom with the main house.
When a standard ADU wins
For almost everyone building for rental income, housing aging parents, or right-sized independent living, a detached ADU is the better investment. It’s a full, private home with its own kitchen, bath, and entrance; it commands real rent (see how much an ADU earns); it adds more property value; and it carries no owner-occupancy requirement, so you keep full flexibility.
Framework First builds detached ADUs from 450 to 1,200 square feet, all fully independent homes, all delivered done-for-you.
Can you have both?
In many cases, yes, California law often allows a single-family lot to add both a JADU (inside the house) and a detached ADU. That can mean two income units or housing two family situations at once. Whether your specific lot qualifies for both is exactly what a feasibility study confirms.
How to choose
Ask one question: do you want to convert existing space, or add a real second home? If it’s “convert,” a JADU is the cheap path. If it’s “add a home”, for rent, family, or value, a detached ADU is what you want, and it’s what we build.
Frequently asked questions
How big can each one be?
A JADU is up to 500 square feet and must be created within the walls of the existing home. A detached ADU can reach up to 1,200 square feet under state law.
Do I have to live on the property?
For a JADU, yes, owner-occupancy is required. For a standard ADU, no; state law removed that requirement, so it can be a pure rental.
Can I build both?
Generally yes: state law lets a single-family lot add one ADU plus one JADU. Some owners convert interior space to a JADU and add a detached ADU for rental income.
Not sure which fits your property and goal? Get a free property analysis and we’ll point you to the right one.