Building an ADU in Santa Clara

What you can build in Santa Clara

Santa Clara must approve these ADUs ministerially, through a Zoning Clearance:

• Single-family parcel: one detached ADU; or one attached ADU or one junior ADU inside the house (an attached garage counts as part of the house); or one converted ADU. You can also combine one detached ADU, one JADU and one converted ADU.
• Multifamily or mixed-use parcel: up to two detached ADUs, plus at least one ADU converted from non-living space (storage rooms, boiler rooms, passageways, attics, basements or garages), and up to 25% of the existing units.

An attached ADU needs its own exterior access. To be approved ministerially, it must match the height of the existing or proposed house (or an existing accessory structure). The city says a second-story ADU that doesn't match the house's height needs Architectural Review. ADUs that don't fit the ministerial categories can still be approved through Architectural Review.

Legal nonconforming conditions (such as old setbacks) don't have to be fixed to get the ADU permit, and unrelated illegal conditions don't have to be corrected first, though the city can still enforce them separately. An ADU on a property listed in the California Register of Historical Resources needs a Significant Property Alteration permit. [1][2]

Size, height and setbacks

Every ADU must be at least 150 sq ft.

Detached ADU. Up to 1,000 sq ft on parcels of 5,500 sq ft or less, and up to 1,200 sq ft on larger parcels. One story and 18 feet tall, with 4-foot rear, side and corner-side setbacks. The handout adds a 6-foot minimum distance from the main home. You can go to 25 feet and 1.5 stories if the multistory parts are 15 feet from the rear line (the code also says 9 feet from the side for two-story elements), dormers are no wider than 40% of the wall, and egress windows face the main house rather than neighbors. A detached ADU may include a detached garage.

Attached ADU. Up to 1,000 sq ft or 50% of the main home, whichever is less, but never less than 800 sq ft. Up to 25 feet and two stories. It must meet the zone's front setback, with 4 feet on the sides and rear for one-story parts, and 15 feet at the rear for multistory parts. (HCD, the state housing agency, says size caps must allow at least 850 sq ft, or 1,000 sq ft with more than one bedroom.)

Lot limits. Front setbacks, parcel coverage, floor area ratio and open space rules apply only as long as they still allow an 800 sq ft ADU at least 18 feet tall with 4-foot side and rear setbacks. ADUs can't sit in a sight-distance triangle at intersections or driveways, and accessory structures can't be in an easement; check easements with Public Works at 408-615-3000. [1][2][3]

Parking

Santa Clara requires no parking for an ADU or JADU. When a garage, carport or covered parking for the house is demolished or converted for the ADU, you don't have to replace those spaces. If you choose to provide replacement parking for a converted ADU, it can be covered, uncovered or tandem, on the driveway leading to a required space or on a paved surface in the rear yard. [1][2]

Fees

You pay permit fees through the city's online permitting portal, and the city's ADU Calculator estimates "potential building costs, rent, and return on investment". Ask the Permit Center at 408-615-2420 for an estimate.

Under state law, an ADU with 750 sq ft or less of interior living space pays no impact fees, and a larger ADU pays fees in proportion to the main home's size. School districts may charge fees on ADUs over 500 sq ft. See our ADU cost guide and financing guide. [3][4][5]

How long it takes

State law requires the city to say within 15 business days whether your application is complete. When a home already exists on the lot, it must approve or deny a complete application within 60 days.

With pre-approved plans, the city says plan review is done "within 10 business days of the City receiving required fee payment, and five business days for subsequent rounds," if your site-specific plans are complete and accurate. See our ADU permit process guide. [3][4]

Garage conversions

A converted ADU is made from part of the existing house (such as an attached garage or storage area) or from an existing accessory structure (such as a detached garage, studio or pool house). It has no size limit; the code gives the example of a 2,000 sq ft accessory structure converted with no size cap. It needs exterior access. You can add up to 150 sq ft only for a way in and out.

A conversion built in the same place and to the same dimensions as the existing structure needs no setbacks. You don't have to add parking or replace the garage spaces. See our garage conversion guide. [1][2]

Junior ADUs

A JADU can be up to 500 sq ft and must be built within the walls of an existing or proposed single-family home. The 150 sq ft expansion isn't available, and JADUs aren't allowed in accessory structures. It needs an efficiency kitchen: a cooking facility with appliances, a food prep counter and storage cabinets. It can share the house's bathroom; if it does, it needs its own entrance plus an inside door to the house. JADUs can't be short-term rentals.

You record a deed restriction saying the JADU can't be sold separately from the house and limiting its size and features.

Owner occupancy. The city's January 2026 handout says the owner must live in the house or the JADU only when the JADU shares a bathroom, which matches state law since January 1, 2026. The zoning code, as published, still requires owner occupancy for every JADU. If your JADU has its own bathroom, confirm with the Planning Division. [1][2][3]

Renting, multifamily lots and state law

All ADU and JADU rentals must be for terms longer than 30 days.

Multifamily lots. Santa Clara's code allows up to two detached ADUs on a multifamily parcel. HCD's handbook says state law now allows up to eight detached ADUs on a lot with an existing multifamily building, as long as they don't outnumber the existing units. If you own a multifamily property, ask the Planning Division how the city applies the newer state rule. See our California ADU law overview.

Lot splits. The city's Planning FAQ explains that under SB 9, a city doesn't have to approve more than two units (including ADUs and JADUs) on a lot created by an urban lot split. See our SB 9 lot split guide. [1][3][5]

Permit steps in Santa Clara

1. Check the rules for your parcel

   Read the city's ADU and JADU handout and the Zoning Code Section 18.60.020. Questions go to the Planning Division at 408-615-2450 or planning@santaclaraca.gov. [2][5]

2. Decide on a custom design or a pre-approved plan

   Hire a designer, or pick a plan from the city's ADU Plans Gallery. To use a pre-approved plan, your lot must be residential with a single-family home or duplex, not in a flood zone and not a historic property; fill out the city's Pre-Approved ADU Checklist. [4]

3. Prepare the site-specific plan set

   Your designer adds a site plan, utility plan, and energy and solar plans if required. Small changes such as window types or rotating the floor plan may be allowed; bigger changes lose the expedited review. [4]

4. Apply and pay fees online

   Apply for permits, upload plans, check status and pay fees through the city's Permitting Online Portal (linked from the Pre-Approved ADU Plans page). [4]

5. Record the JADU deed restriction (if building a JADU)

   Record the deed restriction barring separate sale and limiting the JADU's size and features, and file it with the city. [1][2]

6. Complete plan review, build and pass inspections

   Answer review comments, get the permit, then build and pass city inspections. Revisions after the permit is issued go through regular review, not the expedited pre-approved track. [4]

Pre-approved and sample plans

• Pre-Approved ADU Plans Program

  Detached ADU designs pre-approved by the city or the state (from about 340 to 933 sq ft); you add a site-specific plan set, and the first plan review is done within 10 business days of fee payment. [4]

Who to call

• Planning Division

  ADU zoning standards (planning@santaclaraca.gov)

  408-615-2450

  Permit Center, City Hall, 1500 Warburton Avenue, Santa Clara, CA

  [2][5]

• Permit Center

  Permit applications and general permit questions

  408-615-2420

  [5]

• Public Works Department

  Easements and sight-distance questions

  408-615-3000

  [2]

Questions people ask