Accessory dwelling unit construction cost

Looking for accessory dwelling unit construction cost in San Jose, CA? Call AccessoryDwellingUnit Direct for a contact a provider — no obligation. Licensed adu builders serve San Jose 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 involves variables that shift your total investment. The footprint size and complexity of the architectural design are primary factors. Are you planning a detached unit that requires new utility trenching, or is this a garage conversion that uses existing plumbing? Site accessibility, soil conditions, and your choice of finishes—like luxury flooring versus standard options—also play significant roles. Permitting fees vary widely depending on your local municipality and current zoning requirements. Exact pricing confirmed free on the call.

About this service

The amount you spend depends on the size of the unit, whether you are building from scratch or converting an existing structure, and the quality of your finish materials. Foundations, utility connections, and local labor rates also play a significant role. We provide exact pricing confirmed free on the call.

Frequently asked in San Jose

What are the disadvantages of ADUs in San Jose?

One disadvantage can be the upfront cost of construction. Securing permits and navigating San Jose's specific building regulations can also take time and effort. Additionally, while ADUs increase usable space, they do occupy valuable yard area, which is a consideration for many homeowners.

How much does an ADU cost in California?

ADU costs in California vary widely based on size, materials, and complexity. Factors like foundation type, whether it’s a new build or a conversion, and the specific finishes you choose will impact the total price. It's essential to get a custom quote based on your San Jose property.

What are the rules for ADUs in California?

California has state-level ADU laws aimed at streamlining approvals. These generally include minimum lot sizes and setback requirements, though local jurisdictions like San Jose may have additional specifics. The pros can clarify these rules for your situation.

Is an ADU allowed in San Jose?

Yes, San Jose generally allows ADUs, with specific regulations in place. The city has adopted ordinances to encourage ADU development, but understanding lot coverage, parking, and setback rules is crucial. A local pro can confirm your property's eligibility.

California has offered grants to help offset ADU costs, particularly for very low-income homeowners. These programs often have specific eligibility requirements and funding availability can change. Inquiring about current grant opportunities during your call is a good idea.

Can I convert my garage to an ADU 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

969,655residents

5,449per sq mile

8ZIP codes served

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, Cambrian Park, Almaden Valley, Rose Garden, Berryessa — and every surrounding area.