The Basics · 03
Permits and zoning in San Jose
The permit process is the part homeowners dread most and understand least. The good news is that California spent the last several years making it deliberately boring — and boring is exactly what you want.
Ten years ago, getting a second unit approved in a South Bay neighborhood could mean a hearing, neighbors with opinions, and a discretionary decision that could go either way. That is largely over. A string of state laws pushed ADU approval into what is called ministerial review: if your plans meet the written objective standards, the city checks the boxes and approves. No hearing, no popularity contest.
That single change is why the ADU conversation shifted from whether you are allowed to what you should build. It also means the most valuable thing your design team can do is keep you inside the objective standards, because the moment you ask for an exception, you re-enter the slow, uncertain world.
The process, start to finish
- Feasibility. Before you fall in love with a plan, someone checks the lot: setbacks, height limits, coverage, easements, protected trees, utility locations, and access. A competent builder or designer does this early. A bad one does it after you have paid for drawings.
- Design and construction documents. Site plan, floor plans, elevations, sections, structural details and calculations, and Title 24 energy compliance. This is the package the city reviews, and its completeness is the main thing you control about your timeline.
- Submittal and plan check. The application goes in and is reviewed by planning, building, and typically fire and public works. You get back a set of corrections. This is normal — even good sets get comments.
- Corrections and resubmittal. Your team responds and resubmits. The difference between a project that clears in one cycle and one that grinds through three is almost entirely the quality of the original set.
- Permit issuance and fees. Plan check fees, building permit fees, and any applicable impact or utility connection fees are paid. Then you can build.
- Construction and inspections. Inspections happen at defined stages — foundation, framing, rough plumbing and electrical, insulation, and final. Work covered up before inspection may have to be opened back up.
- Final sign-off. The unit is legal to occupy. Keep the paperwork. You will need it at refinance and at sale.
The objective standards you will keep hearing about
What the city is checking
- Setbacks — how close the unit can sit to rear and side property lines.
- Height — total building height, with different limits for detached versus above-garage units.
- Size — maximum floor area, which varies by ADU type and by bedroom count.
- Lot coverage and open space — how much of the lot can be built on.
- Fire access and egress — distance from the street, separation, sprinkler triggers.
- Parking — state law has significantly limited when cities can require replacement parking.
- Utilities — connection requirements and whether a separate meter is needed.
What state law changed, in plain terms
California has passed a run of ADU bills — AB 68 among the most consequential — with a consistent direction of travel: make it harder for cities to say no. Broadly, the effects have been to shorten review timelines, restrict minimum lot size requirements, limit setback demands, curb parking mandates near transit, and require cities to judge ADU applications against objective written standards rather than discretionary taste.
The practical consequence for you: much of the local folklore about ADUs — that your lot is too small, that you will need to add parking, that a neighbor can block it — is often out of date. Check the current rule rather than the story you were told.
Where permits actually go wrong
In the projects I looked at, delay almost never came from the city being hostile. It came from three places: an incomplete submittal, a design that requested an exception it did not need, and a utility surprise discovered after approval. All three are controlled by the team you hire, which is why permit handling is a criterion on the builder checklist and not an afterthought.
Frequently asked questions
- Do I need a permit to build an ADU in San Jose?
- Yes. Every ADU requires a building permit, and the plans have to be reviewed for zoning compliance, structural safety, and energy code. A garage conversion and a JADU need permits too, even though no new building appears in the yard. Unpermitted work surfaces later at sale, refinance, or insurance claim, and retroactive permitting is far more expensive than doing it in order.
- How long does it take to get an ADU permit in San Jose?
- California law requires cities to approve or deny a complete ADU application within a fixed statutory review window rather than leaving it open-ended, and San Jose has a dedicated ADU review path. The practical timeline is driven less by the city clock and more by how complete your submittal is, and by how many correction cycles your design team causes. Verify the current statutory deadline and San Jose's published turnaround before you plan around a date.
- Do neighbors get a say in my ADU?
- For a standard ADU that meets the objective standards, no. State law made ADU approval ministerial, which means the city checks your plans against written rules rather than holding a discretionary hearing where opinions are weighed. You lose that protection if you request an exception to a standard such as height or setback, which can push the project into a discretionary review.
- What did AB 68 change for ADUs?
- AB 68 was part of a wave of California legislation that reduced local barriers to ADUs — tightening review timelines, limiting the minimum lot size and setback rules a city can impose, and constraining cities' ability to reject units that meet objective standards. Later bills continued in the same direction. Because the details have been amended repeatedly, treat any specific figure you read online as something to confirm against the current code.
- Will an ADU raise my property taxes?
- In California, building an ADU generally triggers a reassessment of the new construction only, rather than a reassessment of the whole property at current market value. The added assessed value is based on the value the ADU adds. Confirm the treatment for your specific project with the Santa Clara County Assessor before you budget the ongoing cost.
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