Santa Clara / Accessory dwelling units
ADU Builder in Santa Clara
Most ADUs and junior ADUs in Santa Clara are filed as a building permit. One attached-unit case is called out for Architectural Review, and a separate pre-approved plan program has its own lot tests. R&B Master Construction Inc. (CSLB #1158657) discusses Santa Clara projects from our San Jose office. Call (650) 800-9661.
Building permit, with one noted exception
Santa Clara’s Planning Division says ADU and junior ADU projects can be submitted as a building permit, except for a new attached second-story ADU on a single-story residence, which requires Architectural Review. Projects that do not meet the ministerial criteria also go through Architectural Review. The City points to City Code section 18.60.020 and the ADU and JADU handout (opens in a new tab).
We sort that path before drawings are frozen. A second-story addition on a one-story house is not the same submittal as a conversion inside an existing building.
Standards in the current handout
The handout revised January 2026 is a summary, not the whole code. It states a minimum floor area of 150 square feet and says no parking is required for an ADU or junior ADU. When a garage, carport, or covered parking structure is converted or demolished for an ADU or junior ADU, those parking spaces need not be replaced.
For detached ADUs, the same handout lists a maximum of 1,000 square feet on parcels of 5,500 square feet or less, and 1,200 square feet on larger parcels. Side and rear setbacks are shown at 4 feet, with a 6-foot separation from the main residence. Detached height is described as 18 feet for one story and 25 feet for a 1.5-story form. Taller forms have extra rear-setback and window rules. Attached units have their own size cap, including at least 800 square feet where state law requires it. These figures describe the handout. They are not an approval for a specific lot.
The handout also says ADUs shall not sit in the sight-distance triangle at street intersections and private driveways, as Public Works determines in its TR-9 visibility handout. Accessory structures cannot be in an easement. Ask Public Works if the lot has one.
Pre-approved plans have a short eligibility list
Santa Clara’s Pre-Approved ADU Plans (opens in a new tab) program lets vendors offer plan sets the Building Division has already reviewed. To use them, the City says the lot must be zoned residential with an existing single-family home or duplex, must not be in a flood zone, and must not be a historic property. You still submit a site-specific plan. The City reviews zoning and solar requirements for that property. Use MAP Santa Clara when you screen zoning and flood information, then confirm with the City.
Questions homeowners ask
Do Santa Clara ADUs need planning entitlement?
Often no — many are ministerial building permits. Attached second-story ADUs on one-story homes are a noted exception needing Architectural Review.
Can I use pre-approved plans?
If the lot qualifies (residential, not flood, not historic). Confirm on the City Pre-Approved ADU Plans page.
Official sources
City rules change. The links below are the pages and documents these notes were checked against. Your address can still differ.
Talk with R&B
R&B Master Construction Inc. · CSLB #1158657. Email info@rbmasterconstruction.com. Headquarters: 84 W Santa Clara St, Suite 700, San Jose, CA 95113. Hours: Monday–Sunday, 7:00 AM–5:00 PM Pacific Time.