What Does an ADU Cost in Silicon Valley? Real Numbers From Real Builds

From garage conversions to detached luxury units, here is what ADUs actually cost in Los Altos, Palo Alto, and Cupertino — and the ROI owners see.

Silicon Valley ADU pricing has little in common with statewide averages. Land value, finish expectations, and city-specific requirements in Los Altos, Palo Alto, and Cupertino push budgets — but they also push returns.

Garage Conversions: $120,000 to $180,000

A 400 sq ft garage conversion with a bath and kitchenette is the fastest, cheapest ADU path — structure already exists. Expect $120,000 to $180,000 depending on foundation condition, sewer tie-in distance, and finish level.

Detached New-Build ADUs: $250,000 to $450,000

A 600-900 sq ft detached unit in Silicon Valley runs $350 to $500 per square foot all-in, including design, permits, utilities, and Title 24 solar. Estate-grade finishes — the kind that match a Los Altos main house — sit at the top of that band.

The ROI Math Owners Actually Care About

A $300,000 ADU renting at $3,200 per month in Palo Alto pays back in under nine years before appreciation — and typically adds $400,000+ to appraised value. For family housing, the math is even simpler.

Want a number for your lot? JMG's ADU division delivers a feasibility review and fixed-scope estimate under License #1007864. Request your consultation today.