Cost to build accessory dwelling unit

Looking for cost to build accessory dwelling unit in San Bernardino, CA? Call AccessoryDwellingUnit Pros for a contact a provider — no obligation. Licensed adu builders serve San Bernardino and the surrounding area, and you'll get straight answers on timing and what affects the price.

Last updated: September 24, 2026

What affects the price

Building an ADU is a custom project, so costs vary based on your specific choices. Site conditions are the biggest factor; if your land requires significant grading, utility extensions, or foundation work, those expenses add up quickly. Choosing high-end finishes, custom cabinetry, or complex roof lines will also push the budget higher compared to a standard design. Prefabricated units often offer predictable costs, while custom site-built structures allow for more flexibility but can be harder to estimate upfront. Exact pricing confirmed free on the call.

About this service

Determining the cost requires looking at site preparation, foundation work, and the level of interior finishing you choose. Costs change based on whether you opt for a pre-designed layout or custom architecture. You should research these costs when you are ready to evaluate the financial return of your property upgrade. Exact pricing confirmed free on the call.

Frequently asked in San Bernardino

What are the disadvantages of ADUs?

How much does an ADU cost in California?

The cost to build an ADU in California, including San Bernardino, depends heavily on its size, design, and chosen materials. Site preparation, like grading or foundation work specific to the local terrain, also impacts pricing. Getting a precise figure requires a site evaluation. A complimentary quote provides the most accurate cost breakdown for your project.

What are the rules for ADUs in California?

California has statewide ADU laws designed to encourage their construction, but San Bernardino may have local zoning ordinances. These can dictate things like how close the ADU can be to property lines or existing structures. It's essential to know these specific requirements. A call to local experts can clarify all applicable rules.

Is an ADU allowed in Maryland?

This service is for San Bernardino, California, not Maryland. ADU regulations are highly localized and vary significantly by state and municipality. If you're in Maryland, you'll need to seek out a local ADU service provider familiar with their specific laws.

What are the rules for ADUs in California?

Also serving nearby: Rialto · Fontana · Jurupa Valley · Rancho Cucamonga · Riverside

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More on this: HUD ADU resources — ADU policy and financing research.

Service area details

223,728residents

3,602per sq mile

8ZIP codes served

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, Del Rosa, South San Bernardino — and every surrounding area.