Cost to build accessory dwelling unit — Antioch, CA
Last updated: September 24, 2026
What affects the price
Building an ADU involves several moving parts that shape your total budget. The biggest factor is whether you choose a prefabricated unit or a custom build on-site. Site preparation is also significant; if your land requires extensive grading, utility trenching, or foundation work, costs will climb. Your choice of finishes—like kitchen cabinetry, flooring, and siding materials—also shifts the bottom line. We help you navigate these variables to find a setup that fits your property. Exact pricing confirmed free on the call.
About this service
When calculating the budget for a secondary unit, consider the costs for architectural design, permits, materials, and labor. Custom designs and high-end interior finishes will push your budget higher, while standardized layouts can keep costs more predictable. Exact pricing confirmed free on the call.
Frequently asked in Antioch
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Also serving nearby: Concord · Fairfield · Tracy · Stockton · Vallejo
More on this: HUD ADU resources — ADU policy and financing research.
Service area details
Serving all of Antioch — population 117,096; about 4,014 residents per square mile across 29.2 sq mi. ZIP codes covered include 94509, 94531.
Neighborhoods served in Antioch: Lakeside, Antioch Marina, Lone Tree, Sycamore, Creekside — and every surrounding area.
Areas we serve
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