Two Detached ADUs in Santa Clara (AB 956, 2027)
Plan Two ADUs in Santa Clara: Free Site Assessment
Santa Clara ADU rules today (2026)
From January 1, 2027, state law (AB 956) requires cities, including Santa Clara, to approve up to two detached ADUs on a lot with a single-family home. Santa Clara revised its ADU and JADU handout in January 2026 and runs a pre-approved ADU plans program, so many of the pieces for a two-unit project are already in place. Here is how the new law and the current local ADU rules fit together.
- Units allowed now: one detached ADU, one attached ADU or one JADU, or the combination of one detached ADU, one JADU and one ADU converted from existing space (City Code Sec. 18.60.020; Planning handout Rev. 01/26).
- Detached ADU size: up to 1,000 sq ft on lots of 5,500 sq ft or less and 1,200 sq ft on larger lots.
- Attached ADU and JADU: an attached ADU can be the lesser of 1,000 sq ft or 50% of the main home, with at least 800 sq ft allowed. A JADU can be up to 500 sq ft. Converted ADUs have no size cap.
- Height: 18 ft for a one-story detached ADU, or 25 ft at 1.5 stories (the maximum).
- Setbacks: 4 ft rear, side and corner side, 15 ft rear for multi-story elements, and 6 ft from the main home.
- Parking: none required for an ADU or JADU, and no replacement for a converted or demolished garage or carport.
- Process: ministerial review for projects that meet the standards. Designs that do not comply go to Architectural Review.
- Pre-approved plans: the Building Division’s program lets vendors pre-review detached designs. A detached garage may be included.
What changes on January 1, 2027
AB 956 requires Santa Clara 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.
Santa Clara allows one new detached ADU on a single-family lot today, and its pre-approved checklist is written for one detached unit on these lots. AB 956 raises that to two. The City’s current 1,000 and 1,200 sq ft limits are above 800 sq ft, so the City may choose to cap each of two units at 800 sq ft. The 6 ft separation from the main home and the 15 ft rear setback for multi-story elements will shape where two units fit. Santa Clara will need to update its ordinance, and we confirm current rules as it does.
Recent Axiom work
Professional photos from a recent Axiom Renovation full remodel and addition in Los Gatos.
Planning two detached ADUs on a Santa Clara lot
- Flood zones: lots in flood zones A, AE, AH or AO cannot use the pre-approved plans program.
- Historic properties: historic-listed lots are excluded from pre-approved plans, and California Register properties need a Significant Property Alteration permit.
- Easements and sight lines: ADUs cannot be placed in easements or sight-distance triangles, which matters on corner lots.
- Two-story units: a detached ADU over one story and 18 ft has dormer limits of 40% of the elevation width, and egress windows must face the main home.
- Electrical: two units plus the main home usually need a load calculation and often a service upgrade.
Building ADUs in Santa Clara with Axiom
Axiom Renovation designs, permits and builds ADUs in Santa Clara. Read our Santa Clara ADU guide, see our Santa Clara service area, or start with the AB 956 overview. Neighbors can read the guides for San Jose and Sunnyvale.
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.
Santa Clara Two-ADU FAQ
Can I build two detached ADUs in Santa Clara?
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. Today Santa Clara allows one detached ADU, with a JADU and a converted ADU in some combinations.
How large can each ADU be in Santa Clara?
Today a detached ADU can be up to 1,000 sq ft on lots of 5,500 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.
How tall can a detached ADU be in Santa Clara?
A one-story detached ADU can be 18 ft tall. A detached ADU can reach 25 ft at 1.5 stories, which is the maximum, with limits on dormers and window placement.
Does Santa Clara require parking for an ADU?
No. Santa Clara requires no parking for an ADU or JADU and no replacement parking when a garage or carport is converted or removed.
Can I use a pre-approved ADU plan in Santa Clara?
Often, yes. The City’s pre-approved program covers detached designs, but lots in certain flood zones, historic-listed lots, sites with easement conflicts and properties with open code-enforcement cases are not eligible.
Who builds two-ADU projects in Santa Clara?
Axiom Renovation designs, permits and builds ADUs in Santa Clara 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.