Cost guide · San Jose · City of San Jose PBCE (Planning, Building & Code Enforcement)
San Jose ADU cost guide — every line, no surprises
A fixed-price San Jose ADU contract is the sum of five line items: base build, City of San Jose PBCE (Planning, Building & Code Enforcement) permits and fees, design and engineering, sitework and utilities, and finishes. Below is how each one moves in San Jose specifically — and where homeowners get burned by quotes that hide them.
City-specific deep dives
- Cost guideOpen the San Jose cost guideEvery line item, 2026 prices, no surprises. The number you should be quoting from.
- Permits guideSan Jose permits guide — plan check, fees, timelinePlan-check workflow, fees, and realistic turnaround for this jurisdiction.
- Timeline guideHow long adu really takes in San JosePhase-by-phase schedule grounded in active builds, not optimistic Gantt charts.
Base build — what $/sqft actually covers
Base build in San Jose runs $385–$520 per square foot for a detached one-bedroom ADU at 2026 pricing. That number assumes Title 24 compliance, code-minimum insulation, mid-grade finishes, and standard MEP. Anything below $360/sqft in San Jose is either skipping permits, skipping engineering, or carrying allowance line-items that will balloon during construction.
City of San Jose PBCE (Planning, Building & Code Enforcement) fees & soft costs
San Jose plan-check, school fees, sewer capacity, water meter, and utility connection fees typically land between $14,000 and $28,000. The variance is driven by lot conditions: a flat San Jose lot on existing sewer is the low end; a hillside lot needing a new lateral and water tap is the high end. We pull these numbers at feasibility, not after deposit.
Design, engineering, and soils
Architectural design, structural engineering, Title 24 compliance, and (when San Jose requires it) a geotechnical report typically run 8–11% of project cost. Hillside-zoned parcels and properties within special review overlays push this higher. We disclose the engineering scope up front so the design fee isn't a moving target.
Sitework, utilities, and the hidden 15%
Sitework in San Jose — demolition, grading, retaining if needed, sewer tie-in, water service upgrade, electrical panel upgrade to 200A — is where most "cheap" quotes blow up. Older San Jose homes nearly always need a panel upgrade and often a lateral upgrade. Budget 12–18% of project cost here. We scope this at survey, before contract.
Finishes — the only line you actually control
Finish allowances (cabinets, counters, flooring, fixtures, appliances) are the single line a San Jose homeowner can move materially up or down. Going from builder-grade to mid-luxe adds roughly $35–$60 per square foot. Going to luxury finishes can add $90+/sqft. We model three finish tiers at design so the trade-off is visible, not buried.
San Jose · Cost guide
Questions San Jose homeowners ask about cost
Direct answers, San Jose-specific.
Should I use a pre-approved San Jose ADU plan?
If one fits your lot and program, yes — it cuts permit time meaningfully. We compare custom vs pre-approved at feasibility.Is San Jose faster than SF or Oakland?
Typically yes — plan-check often clears in 3–5 months, faster than SF (5–8) and on par with the quicker East Bay cities.Does San Jose have unique requirements that affect cost?
Yes — City of San Jose PBCE (Planning, Building & Code Enforcement) sets the local rules, and San Jose has its own plan-check rhythm. The realistic numbers above reflect 2026 San Jose conditions, not statewide averages.
Continue researching San Jose
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