Costs & budgets
How much does an ADU cost in California?
California ADUs cost $85,000–$420,000 in 2026 depending on type and region. Garage conversions run $85K–$165K, attached ADUs $165K–$280K, and detached new builds $230K–$420K. Bay Area pricing trends 15–25% above Greater Los Angeles for identical scopes.
Cost is driven by four buckets: hard construction (60–70%), soft costs like design and engineering (8–12%), city fees and utility upgrades (5–10%), and contingency plus finish upgrades (10–15%).
Hillside lots add $40–$90/sqft for caissons and retaining walls. Two-story builds add $25–$45/sqft. Coastal Zone, HPOZ, and methane-overlay parcels add review fees and timeline.
- Garage conversion — $185–$280/sqft (LA), $215–$330/sqft (Bay Area)
- Detached ADU — $325–$525/sqft (LA), $385–$625/sqft (Bay Area)
- JADU — $90–$190/sqft, capped at 500 sqft
Keep reading
Related questions
- • What's the cheapest type of ADU to build?
- • How much does a 1,200 sqft ADU cost?
- • Why do Bay Area ADUs cost more than LA?
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