ADU Construction cost per square foot in San Jose
ADU Construction cost per square foot in San Jose, California in 2026.
Low
$207,000
Average
$310,500
High
$414,000
San Jose crews quote about $345 – $690 per square foot.
Multiply local unit rates by your real measurements.
What drives adu construction prices in San Jose
Local labor, permitting and climate move San Jose prices away from the national average.
Labor market
Silicon Valley labor is among the priciest in the country, with skilled trades in short supply.
Permits
San Jose requires permits for nearly all remodels; plan check can add 2-4 weeks.
Climate
Mild climate keeps material demands modest, but seismic detailing adds cost.
San Jose unit pricing by material
Ways to lower your San Jose price
- Use pre-approved ADU plans where your city offers them — saves months and design fees.
- Detach only if required; attached and conversion ADUs cost far less.
- Collect three written bids on an identical scope — spreads of 20–40% are normal.
- Book in the off-season and stay flexible on the start date to save 5–15%.
- Bundle nearby work into one mobilization so you only pay setup and travel once.
- Ask what the contractor would change to cut 10% without hurting durability.
San Jose questions
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