Accessory dwelling unit massachusetts — 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

Building an ADU in Massachusetts involves navigating specific state-level zoning reforms designed to make it easier for homeowners to add secondary housing. Whether you are in a dense city or a suburban town, you must follow local bylaws regarding size, height, and parking. You need this service if you own property in the state and want to add a legal unit for aging parents or tenants. Costs depend heavily on local permit fees and site conditions. 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, Berryessa, Japantown, Rose Garden — and every surrounding area.