Accessory dwelling unit services — 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

These services cover the entire lifecycle of building a backyard home, from initial property assessments and architectural design to navigating local zoning permits. You need this when you want to add living space to your property but don’t know where to start with city regulations or site feasibility. Professionals handle the paperwork, site planning, and technical requirements so you can focus on the final layout and how you plan to use the additional square footage on your lot.

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, Campbell — and every surrounding area.