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ADU answers
ModeledFeasibilityReviewed 2026-04-24

Detached ADU vs attached ADU vs garage conversion vs JADU

How common ADU and JADU options differ, and why ADUOS ranks the likely path for a San Jose property instead of assuming one answer.

Direct answer

The short version

Modeled

ADUOS screens detached ADU, attached ADU, existing-space or garage conversion, and JADU as separate options. The strongest path depends on the lot, existing home, access, utilities, and what the homeowner is trying to accomplish.

San Jose scope

Where this applies

Verified

San Jose and California sources distinguish ADUs from JADUs. ADUOS screens both only inside its supported San Jose scope.

ADUOS checks

What we check first

  • Whether detached space appears plausibleModeled
  • Whether attached or conversion paths avoid obvious lot conflictsModeled
  • Whether a JADU path depends on existing interior spaceModeled
  • Whether the path creates utility, parking, or access review itemsNeeds review
  • Which path is the strongest current fitModeled

What could change this

The answer can move

  • Interior layout evidenceNeeds review
  • Garage condition and legal statusNeeds review
  • Utility service constraintsNeeds review
  • Homeowner goal: family use, rental income, or flexible spaceModeled

Source notes

Why the label matters

Modeled

The ADU and JADU categories are source-backed. The ranking is property-specific and should be treated as Modeled unless enough evidence is verified.

FAQ

Common follow-ups

Is detached always better?
Modeled

No. Detached can be appealing, but attached or conversion paths may be more realistic when lot space or access is tight.

Is a JADU the same as an ADU?
Verified

No. A JADU is a distinct path with its own limits and requirements. It can be useful, but it should not be treated as a shortcut without review.