JADU vs ADU vs detached ADU: the real differences

California's ADU statute distinguishes between attached, detached, and junior ADUs because each was added to the law at a different time to solve a different problem. HCD's ADU Handbook walks through the distinctions HCD ADU Handbook and the underlying statute is in Government Code §65852.2 and §65852.22 California Gov Code §65852.2 + §65852.22.

For LA homeowners, the practical question is almost always: am I willing to give up interior space in my main house, or do I want a fully separate unit? The answer determines which format you should pursue.

150 to 500 square feet, carved out of existing conditioned space inside the main single-family home. Must include a small efficiency kitchen. May share a bathroom with the main house. Requires owner-occupancy of either the main house or the JADU. Cannot be sold separately.

Best fit: a homeowner who has an underused bedroom or finished basement and wants to add a legal rentable or family-use unit at the lowest possible cost. Hard cost typically lands $50,000–$90,000 for a clean conversion. Maxable has a clear JADU explainer Maxable — JADU explainer and Symbium's lookup tool flags JADU eligibility Symbium — JADU eligibility tool.

Shares at least one wall with the existing main house. Capped at 1,200 sqft, but in practice limited to 50% of the main house's existing floor area (whichever is smaller, with a 800 sqft minimum allowance regardless). Can be a conversion of attached garage space or new construction.

Best fit: lots where setback geometry rules out a detached structure, or homeowners who want to expand the main house footprint and create the ADU as part of the same project.

A standalone structure separated from the main house. Capped at 1,200 sqft regardless of main-house size. No owner-occupancy requirement (in most jurisdictions including LA, through current law).

Best fit: lots with usable backyard depth, owners who want maximum flexibility (rental, family use, eventual condo conversion if the city ever opts into AB 1033), and projects where the unit's privacy and independence matter for either rent or use. UCLA Lewis Center research shows detached units make up the majority of new LA ADU construction UCLA Lewis Center — LA ADU production data.

California law allows one JADU and one ADU on the same single-family lot. That means a homeowner can carve a 400 sqft JADU out of the main house AND build a 1,200 sqft detached ADU in the back — three legal units on a single-family lot, all under ministerial approval. The statute is clear on this California Legislative Information and HCD's memos confirm HCD ADU technical assistance memo.

On a multifamily lot, SB 1211 expanded the count further — up to 8 detached ADUs depending on the existing unit count Terner Center SB 1211 analysis. The LA Times has covered the resulting density potential LA Times — density coverage and Curbed LA tracks specific projects Curbed LA — project tracking.