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Building an ADU in Santa Clara

The pre-approved plan program is the city's main cost and time advantage: a 75% plan-review fee discount and a 10-business-day first review. Local rules are mostly state baseline, with one trap: a second-storey unit that does not match the main home's height loses ministerial review.

Pre-approved plans

Checked 2026-09-10

Building Division program (revised April 2026): plan review at 25% of the standard fee and a 10-business-day first review for unchanged pre-approved plans. Under state law a detached unit built from a pre-approved plan gets a 30-day decision instead of 60.

Program page →

Programs and incentives

  • Active

    75% plan-review fee discount on pre-approved plans

    Projects with no or minor changes to a pre-approved plan pay 25% of the standard plan-review fee and skip the expedited surcharge.

    Santa Clara's page → Checked 2026-09-10
  • Active

    Paid expedited review

    Optional expedited plan review at +50% of the regular fee, by appointment.

    Santa Clara's page → Checked 2026-09-10

Local rules worth knowing

  • Review path. ADUs submit as a building permit with no planning entitlement, except a new attached second-storey unit on a single-storey home, which needs Architectural Review.
  • Second storey. A second-storey ADU is ministerial only if it matches the height of the main home.
  • Conversions. No setback required for a conversion rebuilt in the same location and dimensions, or for a unit within existing space.
  • JADU. Up to 500 sq ft within the walls of the house, including an attached garage; may share a bathroom.
  • Size. The planning FAQ says 1,000 sq ft or 50% of the main unit; the 2026 handout says 'generally 220 to 1,200 sq ft'. The two disagree; state minimums control. Confirm with planning.

We build here

Santa Clara is inside our service area, and ADUs are all we do. We bring in the architect and engineer or work with yours, run the permit with Santa Clara, and build with our own crew: about 6 weeks of construction for a detached unit once the permit is in hand.

What we can't tell you from here is what your particular lot will take: setbacks, the sewer lateral, the panel, grade and access. That is what the free site walk is for.

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Text updates

Replies to your questions, site walk reminders and project status, sent to your phone by Bayfront Contracting (Bayfront ADU). You can stop them at any time.

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