What does an ADU cost in San Jose? What 497 city permits show
Updated Oct 22, 2026 · city permit data downloaded Oct 20, 2026 · by Carlos Morones
San Jose ADU permits issued Oct 20, 2025–Oct 20, 2026 declared a median construction valuation of $108,556. The middle half ran $77,053–$134,934 (497 permits). That's the value declared for permit fees, not a contract price, and it usually leaves out design, utility and site costs. Treat it as a floor for planning, not a quote.
If you're planning one, here are licensed ADU builders and general contractors in San Jose: 2,202 active B General Building licensees with a San Jose address in CSLB's Oct 20, 2026 file, listed A–Z.
The spread
| Declared valuation | Permits |
|---|---|
| Under $50,000 | 14 |
| $50,000–99,999 | 210 |
| $100,000–149,999 | 178 |
| $150,000–199,999 | 68 |
| $200,000–299,999 | 19 |
| $300,000+ | 8 |
| All ADU permits | 497 |
| Point in the range | Declared valuation |
|---|---|
| 10th percentile | $62,082 |
| 25th percentile | $77,053 |
| Median | $108,556 |
| 75th percentile | $134,934 |
| 90th percentile | $172,772 |
What the valuation is, and what it isn't
The valuation is the construction value written on the permit, which the city uses to set permit fees. It isn't what a homeowner paid a builder. Here's why it's worth reading carefully:
- It's mostly a size number. 487 of the 497 permits list square footage. Of those, 297 come out to exactly $169.09 per square foot and 133 to exactly $175.92. Valuations that land on the same two rates look calculated from floor area, not taken from bids. The median ADU here was 626 sq ft (middle half 445–799).
- It leaves things out. A construction valuation usually doesn't include design and engineering, permit and impact fees, utility connections or site work.
- Only active permits are in the file. The city's dataset is "Active Building Permits." Permits that were finaled or expired drop out, so this isn't every ADU permit issued in the year.
- No estimate here goes beyond the permits. We don't have bid or contract data, so we're not going to guess one.
Who builds ADUs, license-wise
A new ADU involves several unrelated trades (framing, plumbing, electrical, roofing and more), which is the kind of job a B General Building license covers. Specialty contractors like C-36 plumbers, C-10 electricians and C-39 roofers often work under the B contractor as subs, and each needs their own license for their part. In the city's file, 236 of the 497 permits name a contractor.
Check the builder before you sign
Get the license number from every bid, then check the builder's license: status, class, bond and workers' comp. On a project this size, also ask for a certificate of liability insurance and call the insurer. CSLB's record doesn't show it.
How we computed this
- Dataset: City of San Jose, Active Building Permits (data.sanjoseca.gov), downloaded Oct 20, 2026.
- Filter: permit subtype starting with "ADU" (Accessory Dwelling Unit), issue date Oct 20, 2025 through Oct 20, 2026, valuation above $0. 9 permits with no valuation were dropped.
- Result: n = 497, issued Oct 21, 2025 to Oct 16, 2026. Percentiles are of the declared valuation.
- Script: seo-strategy/data/sj_permit_valuations.py in the site's repository. Full notes: how we computed this.
More for San Jose: all licensed trades in San Jose.
California Trusted Pros isn't affiliated with the City of San Jose or CSLB. This page isn't a cost estimate or financial advice.