Accessory dwelling unit permit cost — 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

Permit fees are paid to your local municipality and fluctuate based on the specific city or county where your property is located. These costs cover plan reviews, impact fees, and safety inspections required to make your new space legal and compliant. Because every jurisdiction has a different fee structure, the final amount depends on your specific town’s regulations. We help you estimate these during the planning phase. Exact pricing confirmed free on the call.

Frequently asked in San Jose

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

All cities in California →

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, Rose Garden, Japantown, Downtown San Jose, The Alamitos — and every surrounding area.