Two Detached ADUs in San Jose (AB 956, 2027)
Plan Two ADUs in San Jose: Free Site Assessment
San Jose ADU rules today (2026)
From January 1, 2027, state law (AB 956) requires cities, including San Jose, to approve up to two detached ADUs on a lot with a single-family home. San Jose’s preapproved ADU program lists about 46 plan options from about 23 vendors, with same-day permits for complete applications. Here is how the new law and the current local ADU rules fit together.
- Units allowed now: under City rules, one attached or detached ADU plus one JADU on a single-family lot. A second ADU is possible today only by converting existing space or an existing structure under state rules.
- Size: up to 1,000 sq ft on lots of 9,000 sq ft or less and 1,200 sq ft on larger lots. An attached ADU is capped at 50% of the main home, but 800 sq ft is always allowed. A JADU can be up to 500 sq ft.
- Height: two-story detached ADUs are allowed. The City’s 2024 ADU presentation lists a 25 ft City height limit, compared with 18 ft under the state route.
- Setbacks and separation: 0 ft side and rear under City rules if fire and building codes are met; 4 ft on the state route and for second stories. Detached ADUs sit at least 6 ft from the main home.
- Parking: the City has eliminated ADU parking requirements, and converted garages need no replacement parking.
- Process: a ministerial building permit. Plans are submitted through SJePlans and tracked on SJPermits.org Rules come from Ord. No. 30516 (effective February 26, 2021) and later updates.
- Preapproved ADUs: plans run from about 330 sq ft to 1,200 sq ft, and a complete submittal can get a permit the same day at the plan review meeting.
State review of San Jose's ADU rules
On December 10, 2025, the state Department of Housing and Community Development (HCD) sent San Jose a technical assistance letter. HCD said the latest ADU ordinance on its file is from 2021 and may be outdated and out of compliance. It listed later state changes, such as a 15-business-day completeness check. HCD asked the City to respond by January 9, 2026, by explaining how it complies or giving a plan to amend its rules. Where local rules are stricter than state law, state law applies.
Recent Axiom work
Professional photos from a recent Axiom Renovation full remodel and addition in Los Gatos.
What changes on January 1, 2027
AB 956 requires San Jose to approve up to two detached, new-construction ADUs on a lot with a single-family home. Each of the two may be limited to 800 sq ft of living space, local height limits can still apply, and side and rear setbacks can be no more than 4 ft. Where two detached ADUs are built, a JADU on the same lot does not have to be approved. Owners in HOAs also gain protections.
Today San Jose allows one new detached ADU. AB 956 makes room for a second one without converting existing space. Size matters: the City has warned that a state-route unit built even slightly larger than 800 sq ft or taller than 18 ft can block a second ADU, so we size each unit carefully. San Jose also opted into condo-style separate sale of ADUs under AB 1033 in 2024, as reported by Assemblymember Ash Kalra’s office. The City will need to update its ordinance, and we confirm current rules as it does.
Planning two detached ADUs on a San Jose lot
- Fire review: a Water Flow Letter and Hydrant Map are part of the submittal. Hydrants, water flow and sprinklers are reviewed.
- Preapproved plan limits: geohazard, landslide, flood and wildland-urban interface zones, Fire Variance sites and open code-enforcement cases are excluded.
- Riparian setback: on lots of half an acre or more, an ADU must stay more than 100 ft from a riparian corridor.
Building ADUs in San Jose with Axiom
Axiom Renovation is based in San Jose and builds ADUs across the city. Read our San Jose ADU guide, see our San Jose service area, or start with the AB 956 overview. Neighbors can read the guides for Santa Clara and Campbell.
Process
Our ADU Process
Step 1
Initial Consultation
We begin with a thorough initial consultation to understand your needs, assess your space, and discuss your vision, budget, and timeline.
Step 2
Planning and Design
At Axiom Renovation, we understand that the planning and design phase of an ADU project is crucial to its success. Our dedicated project managers will work closely with you to understand your goals, design ideas and budget for the project.
Step 3
Material Selection
We guide you through selecting high-quality materials that fit your design and budget, ensuring durability and aesthetic appeal.
Step 4
Demolition and Preparation
Careful demolition and preparation work are performed to ready the space for construction, minimizing disruptions and ensuring a clean work environment.
Step 5
Construction and Installation
Our skilled craftsmen handle the construction phase, including obtaining permits, scheduling appointments, and the actual construction and installation with precision, building the new space according to the approved design.
Step 6
Electrical and Plumbing Work
Licensed professionals conduct all electrical and plumbing work, ensuring everything is up to code and seamlessly integrated into the new ADU.
Step 7
Painting and Finishing
We pay close attention to detail during the painting and finishing stage, ensuring all surfaces are properly prepared and beautifully finished.
Step 8
Fixture and Appliance Installation
We expertly install all fixtures and appliances, ensuring they function correctly and fit perfectly with the overall design.
Step 9
Final Touches and Clean-Up
Final touches are added, and a thorough clean-up is performed, leaving your new space pristine and ready for use.
Step 10
Final Walkthrough and Client Satisfaction
We conduct a final walkthrough with you to ensure every detail meets your expectations and address any remaining concerns, ensuring your complete satisfaction.
San Jose Two-ADU FAQ
Can I build two detached ADUs in San Jose?
From January 1, 2027, AB 956 requires the City to approve up to two detached, new-construction ADUs on a lot with a single-family home, if the project meets objective standards. Until then, San Jose allows one new attached or detached ADU plus a JADU, and a second ADU only by converting existing space.
How large can each ADU be in San Jose?
Today a San Jose ADU can be up to 1,000 sq ft on lots of 9,000 sq ft or less and 1,200 sq ft on larger lots. Under AB 956, the City may limit each of two detached ADUs to 800 sq ft of living space.
Can I build a two-story ADU in San Jose?
Yes. San Jose allows two-story detached ADUs under its City rules, and its 2024 ADU presentation lists a 25 ft City height limit. Second stories need 4 ft side and rear setbacks.
How fast can I get an ADU permit in San Jose?
With a preapproved plan and a complete site-specific submittal, San Jose can issue the permit the same day at the plan review meeting. Deferred structural items take longer. Other ADUs follow the state 60-day decision clock.
Can I sell an ADU separately in San Jose?
San Jose opted into AB 1033 in 2024, which allows condo-style separate sale of an ADU, as reported by Assemblymember Ash Kalra’s office. The process has its own requirements, so we review it with each owner who is interested.
Who builds two-ADU projects in San Jose?
Axiom Renovation designs, permits and builds ADUs in San Jose and is planning two-unit projects for 2027. Call 408-702-2022, Monday to Friday, 9 am to 5 pm.
Sources: AB 956 (Quirk-Silva), signed September 29, 2026, effective January 1, 2027, as summarized by Brownstein Hyatt Farber Schreck and California YIMBY. This page is general information, not legal advice. Local rules change; we confirm current requirements with the City for every project.