Direct answer
The short version
The honest first answer is a range, not one number. San Jose ADU cost depends on path type, size, site work, utilities, design, fees, finish level, and what the lot makes easy or expensive.
San Jose scope
Where this applies
ADUOS does not publish a universal San Jose project price as fact. Official sources help with fee structure and process; total project cost remains Modeled until the case is specific.
ADUOS checks
What we check first
- Likely path and size rangeModeled
- Site and utility surprise riskModeled
- Permit and fee categoriesVerified
- Whether the estimate is a modeled range or verified invoiceModeled
- Which assumptions could move the number mostNeeds review
What could change this
The answer can move
- Utility upgradesNeeds review
- Foundation and drainage conditionsNeeds review
- Designer and builder scopeNeeds review
- Permit comments and correction roundsNeeds review
- Finish level and owner choicesModeled
Source notes
Why the label matters
City sources can support fee and process categories. Builder pricing, utility work, and site conditions are not verified until project-specific evidence exists.
FAQ
Common follow-ups
Why not show one cost number?
One number hides the parts that usually surprise homeowners. A range with assumptions is more honest.
Are prefab prices enough?
No. A low unit price can exclude site work, utilities, permits, design, foundation, transport, and installation details.