Cost to build accessory dwelling unit — San Bernardino, CA
Last updated: September 24, 2026
What affects the price
Building an ADU involves several moving parts that shape your total investment. The final figure depends heavily on whether you choose a prefab unit or a custom build from the ground up. Site conditions are another major factor; if your property requires extensive grading, utility trenching, or foundation work, costs will climb. You also have to consider your choice of finishes, like high-end appliances or custom cabinetry. Navigating local permit fees and impact assessments also adds to the total.
About this service
When estimating the cost to build, consider the difference between a prefab unit and custom construction, as well as site preparation requirements like clearing trees or grading land. Labor and material prices also play a significant role. We provide an exact pricing confirmed free on the call.
Frequently asked in San Bernardino
How do I find a good ADU builder in San Bernardino?
What should I expect from an ADU company in San Bernardino?
What's involved in getting an accessory dwelling unit permit in San Bernardino?
How do I get an ADU estimate in San Bernardino?
What factors influence the cost of an accessory dwelling unit in San Bernardino?
Are prefab ADUs a good option in San Bernardino?
How can I use an ADU for rental income in San Bernardino?
Also serving nearby: Rialto · Fontana · Jurupa Valley · Rancho Cucamonga · Riverside
More on this: HUD ADU resources — ADU policy and financing research.
Service area details
Serving all of San Bernardino — population 223,728; about 3,602 residents per square mile across 62.1 sq mi. ZIP codes covered include 92401, 92402, 92403, 92404, 92405, 92406, 92407, 92408.
Neighborhoods served in San Bernardino: Downtown San Bernardino, Muscoy, North San Bernardino, South San Bernardino, West San Bernardino — and every surrounding area.
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