ADU answers - San Jose
Clear answers before you spend money.
ADUOS Answers is a San Jose-first guide library for homeowners making ADU decisions. Short answers, visible uncertainty, and one next step: check the actual address.
First 12 answers
Built for qualified homeowner intent.
Feasibility
ModeledCan I build an ADU in San Jose?
Maybe. In San Jose, the useful first answer is not whether ADUs are allowed in general. It is whether an ADU looks realistic at your specific address after parcel, zoning, setbacks, access, utilities, and source quality are checked.
Feasibility
ModeledWhat blocks an ADU in San Jose?
The biggest blockers are usually not the idea of an ADU. They are property-specific facts: the parcel match, setbacks, buildable space, access, utilities, easements, existing structures, and evidence gaps that need review before money is spent.
Rules
ModeledSan Jose ADU setbacks, explained in plain English
Setbacks are the required distances between a structure and property lines or other regulated areas. For ADUs, the practical question is whether your lot has enough usable space after the setback rules and parcel geometry are applied.
Feasibility
ModeledDetached ADU vs attached ADU vs garage conversion vs JADU
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.
Cost
ModeledWhat does an ADU really cost in San Jose?
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.
Execution
ModeledSan Jose ADU feasibility checklist
Before you pay for design or builder work, confirm the address, parcel, path screen, top blockers, evidence gaps, and next real step. If those are unclear, the project is not ready for expensive decisions.
Execution
ModeledWhat to check before paying an ADU designer
Before paying for ADU design, check whether the property has a plausible path, what the biggest blockers are, and whether the designer is solving the right problem for the lot.
Cost
ModeledWhy ADU builder estimates are often wrong
ADU estimates are often wrong because they answer a smaller question than the homeowner is asking. A builder price may describe a structure, while the real project also includes site work, utilities, design, fees, corrections, and unknowns.
Feasibility
ModeledGarage conversion ADUs in San Jose
A garage conversion can be a strong ADU path when existing space avoids some lot-fit problems. It still needs review for code, structure, utilities, legal status, access, and whether the conversion path matches the homeowner's goal.
Rules
VerifiedSB 9 vs ADU: what homeowners should know
An ADU is an accessory unit on a property. SB 9 is a separate California housing law path for certain two-unit developments and urban lot splits. They can affect strategy, but they are not the same decision.
Cost
ModeledUtility and site surprises that can break an ADU budget
Utility and site surprises can turn a plausible ADU into a much more expensive project. The risk is highest when public data looks clean but panel, trenching, access, drainage, or existing-condition evidence is still missing.
Trust
VerifiedVerified vs Modeled vs Needs review
Verified means current evidence supports the claim. Modeled means ADUOS reasoned from facts and assumptions. Needs review means the answer depends on evidence that is not available yet.
Editorial rule
No generic ADU sludge.
Every page stays San Jose-first and maps claims to Verified, Modeled, or Needs review. If a page cannot help a homeowner decide what to do next, it does not belong here.