Short answer. A JADU is a 500-square-foot unit inside an existing home and requires owner occupancy. An ADU is a 600 to 1,200 square foot independent unit and does not require owner occupancy. Build a JADU when you want quick, cheap rental income from spare interior space. Build an ADU when you want a full second unit with its own footprint, more rental income, and higher resale value.
Side-by-side comparison
| Factor | JADU | ADU |
|---|---|---|
| Maximum size | 500 sq ft | 1,200 sq ft detached, 1,000 sq ft attached |
| Location | Inside the main house | Attached or detached on the lot |
| Owner occupancy required | Yes | No (through 2025 permit issuance) |
| Kitchen | Efficiency kitchen | Full kitchen |
| Bathroom | Shared or private | Private |
| Separate entrance | Required | Required |
| Typical cost in California | $80,000 to $180,000 | $250,000 to $500,000 |
| Permit timeline | 2 to 6 weeks | 4 to 10 weeks |
| Governing statute | Gov Code 65852.22 | Gov Code 65852.2 |
When a JADU is the right choice
- You have unused interior space (a den, a downstairs guest suite, or an oversized primary bedroom suite) that can be carved out into a 500 square foot unit.
- You plan to live in the main house and rent the JADU for supplemental income.
- Your budget is below $200,000 and you want a permitted second unit.
- You want a fast permit. Most JADU plans approve inside 6 weeks.
When an ADU is the right choice
- You want a fully independent rental unit with its own kitchen, laundry, and entrance.
- You expect to rent at market rate for a one-bedroom or two-bedroom unit.
- You want maximum resale value from the addition. A detached ADU appraises higher than an interior JADU on most LA lots.
- You want flexibility to refinance the property or sell the lot with a tenant in place.
Combine both: California allows it
California law allows one ADU plus one JADU on the same single-family lot. Owners who want to maximize rental income often build both: a detached 800 to 1,200 square foot ADU in the backyard and a 400 to 500 square foot JADU carved out of the main home. The total cost typically runs $350,000 to $600,000 and produces two distinct rental incomes on a single lot.
For full pricing context, read ADU cost in Los Angeles and how much does an ADU cost in California. For the conversion path, read garage conversion ADU cost. Then start the build on the ADU service page.
