Backyard accessory dwelling unit — San Jose, CA

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

A backyard ADU is a detached small home built on your property, separate from your main house. People typically build these to create extra living space for family members, as a private home office, or to gain additional rental income. Because they are freestanding, you will need to consider utility hookups, site access for crews, and local setback requirements. Costs vary based on the foundation type and utility connections. Exact pricing confirmed free on the call.

Frequently asked in San Jose

Also serving nearby: Burbank · Santa Clara · Sunnyvale · Fremont · Hayward

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

Service area details

Serving all of San Jose — population 969,655; about 5,449 residents per square mile across 177.9 sq mi. ZIP codes covered include 95025, 95101, 95103, 95106, 95108, 95109, 95110, 95111.

Neighborhoods served in San Jose: Willow Glen, Almaden Valley, Berryessa, Downtown San Jose, Campbell — and every surrounding area.