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Building an ADU in Campbell, CA

Checked against the city's ADU pages on Oct 18, 2026.

Can I build one?
Yes, up to 1,200 sq ft Under local standards a detached ADU can be 1,200 sq ft and 20 ft tall. No parking required.[1]
What will the city charge?
6 fee lines The city doesn't publish a total for an ADU, so we list each charge. See every fee[2]
Who builds here?
9 licensed builders Each lists Campbell on its own site and holds an active CSLB license. See the list
See 9 builders Get quotes

Campbell has two paths. Local standards allow one ADU of any type. The by-right path allows a conversion, a JADU and an 800 sq ft detached ADU. You can combine them.[1] Compare them

Licensed ADU builders in Campbell

Ranked by a public score anyone can check: license, years licensed, ADU types and cities shown on their own sites, a local office, and published prices. Nobody pays to move up. Quote requests go to our team with the builder you picked. How we rank

What Campbell allows

Campbell has two paths. Local standards allow one ADU of any type. The by-right path allows a conversion, a JADU and an 800 sq ft detached ADU. You can combine them.

  • Detached ADU, max size[1]

    Local standards
    1,200 sq ft
    By-right path
    800 sq ft

  • Attached ADU, max size[1]

    Local standards
    50% of the main home, but 1,000 sq ft is always allowed
    By-right path
    Not part of this path

  • Junior ADU (inside the house)[1]

    Local standards
    Up to 500 sq ft, inside the house or attached garage
    By-right path
    Up to 500 sq ft, inside the house or attached garage

  • Height[1]

    Local standards
    20 ft detached; attached same as the house
    By-right path
    20 ft

  • Side and rear setbacks[1]

    Local standards
    4 ft side and rear; 10 ft from the main home in front or behind, 5 ft beside
    By-right path
    4 ft side and rear

  • Floor area and lot coverage[1]

    Local standards
    Same limits as the lot, except an ADU up to 800 sq ft with 4 ft setbacks
    By-right path
    Exempt

  • Units on a single-family lot[1]

    Local standards
    1 ADU (attached, detached or conversion) + 1 JADU
    By-right path
    1 conversion + 1 JADU + 1 detached ADU

  • Parking[1]

    Local standards
    None; removed spaces don't need replacing
    By-right path
    None; removed spaces don't need replacing

  • Owner must live on site[1]

    Local standards
    No for an ADU; yes for a JADU, with a deed restriction recorded before the building permit
    By-right path
    No for an ADU; yes for a JADU, with a deed restriction recorded before the building permit
  • On a historic property, a detached ADU is limited to 18 ft and one story and must sit in the rear half of the lot.[1]
  • Rules are in Campbell Municipal Code Chapter 21.23. Interim urgency Ordinance 2322 was adopted Feb 18, 2025 for 45 days; we could not confirm whether it was extended or replaced.[3][4]
ADU rules in Campbell drawn on a typical lot Detached ADU, local standards: up to 1,200 square feet, 4 feet from side and rear lot lines, 20 feet tall. Parking: None required. Rear lot line Street Main house ADU up to 1,200 sq ft 20 ft tall 4 ft 4 ft 10 ft apart Parking: none required
Detached ADU, local standards. Not to scale.

City fees for an ADU in Campbell

Fee lines for an ADU in Campbell
Building permit, by valuation 2.00% of the first $500,000 of valuation ($237 minimum)[2] Plan check adds 33% of the permit fee. Fire plan check adds $119 or 10%, whichever is greater. FY 2027 schedule, effective July 1, 2026.
Valuation and size add-ons General Plan 0.16%, technology 0.04%, training 0.02% and roadway 0.32% of valuation, plus $0.50 per sq ft construction license tax[2]
Planning plan check $259 detached; $517 attached; $647 conversion[2]
Park in-lieu fee $0 under 750 sq ft; up to $9,328 at 750 sq ft and up; $0 for a JADU[2] Figured under state law and capped at that amount. A new single-family home pays $33,025.
School fees $1.61 to $3.79 per sq ft by district[5][6][7][8] Campbell Union SD charges $3.79 and Campbell Union HSD $1.61. Parts of the city may be in Moreland or Cambrian districts instead. Ask your districts before you budget.
Sewer connection (West Valley Sanitation District) $6,727 max connection + $1,024 max treatment plant capacity[9] Smaller ADUs pay $511.16 and $73.53 per drainage fixture unit. The district's fee tables are labeled FY2018/19 to FY2020/21.
School fee rates for districts in Campbell (4)

The city publishes no school district map. Campbell Union HSD lists the City of Campbell; Cambrian's coverage of Campbell is not confirmed.[6]

  • Campbell Union School District[5]Charges ADUs over 500 sq ft. $3.79/sq ft
  • Campbell Union High School District[6] $1.61/sq ft
  • Moreland School District[7] $3.35/sq ft
  • Cambrian School District[8]Additions of 500 sq ft or less are exempt. $3.77/sq ft
Total cost in Campbell, fees plus building

How the permit works

  1. 1

    Pick a path

    Choose local standards (one ADU up to 1,200 sq ft) or the by-right path (up to an 800 sq ft detached ADU plus a conversion and a JADU).[1]

  2. 2

    Prepare plans

    Use your own designer or a plan from the Campbell ADU Plans Gallery on the countywide site.[10]

  3. 3

    Apply to the Building Division

    No planning approval is needed. Submit a complete application through MyGovernmentOnline (MGO). Building Division: 408-866-2130.[1]

  4. 4

    Pay fees and get the permit

    Building, planning plan check and any park fee follow the FY 2027 Master Fee Schedule. School and sewer fees go to those districts.[2][9]

  5. 5

    Build and pass inspections

    Re-inspections cost $237 an hour.[2]

State deadline: State law gives the city 15 business days to say if your application is complete and 60 days to approve or deny a complete one.[11]

Preapproved plans

Campbell lists pre-approved plans in its ADU Plans Gallery, part of the countywide Santa Clara County ADU program.[10]

The gallery (campbellca.aduaccelerator.org/gallery) only loads in a browser. We could not read its plan list, and no prices are published.

Common questions

What are the Campbell ADU requirements?

Under local standards a detached ADU can be 1,200 sq ft and 20 ft tall, with 4 ft side and rear setbacks. It must be 10 ft from the main home if in front or behind, or 5 ft if beside it. You apply straight to the Building Division with no planning approval.[1]

How big can an ADU be in Campbell?

1,200 sq ft for a detached ADU under local standards, or 800 sq ft on the by-right path. An attached ADU can be half the main home, and 1,000 sq ft is always allowed. A junior ADU is up to 500 sq ft.[1]

Do I need parking for an ADU in Campbell?

No. Campbell requires no parking for an ADU or JADU, and spaces you remove don't need replacing.[1]

How much is the Campbell ADU permit cost?

The city publishes no total. The building permit is 2% of valuation, plus 33% for plan check and other add-ons. ADUs under 750 sq ft pay no park fee; sewer connection runs up to $6,727 plus $1,024.[2][9]

Can I build more than one ADU in Campbell?

Yes. The by-right path allows a conversion, a JADU and an 800 sq ft detached ADU on one single-family lot.[1]

Nearby cities

What we couldn't confirm

  • Campbell Municipal Code Chapter 21.23 text not read; status of Ordinance 2322 not confirmed.
  • Water provider and water connection fees not identified.
  • No published plan review time.
  • Pre-approved gallery plans and prices not captured.
  • The city publishes no school district map.

Sources

Every fact on this page links to one of these. We read each one on the date shown.

  1. 1. City of Campbell Community Development Local vs by-right standards Checked Oct 18, 2026
  2. 2. City of Campbell Valuation-based building permit % Checked Oct 18, 2026
  3. 3. City of Campbell ADUs governed by Campbell Municipal Code Chapter 21.23 Checked Oct 18, 2026
  4. 4. City of Campbell Adopted Feb 18, 2025 Checked Oct 18, 2026
  5. 5. Campbell Union SD Residential & ADU $3.79/sq ft Checked Oct 18, 2026
  6. 6. Campbell Union HSD $1.61/sq ft eff Checked Oct 18, 2026
  7. 7. Moreland School District Residential $3.35/sf Checked Oct 18, 2026
  8. 8. Cambrian School District Eff Checked Oct 18, 2026
  9. 9. West Valley Sanitation District ADU connection $6,727 max/$511.16 per DFU Checked Oct 18, 2026
  10. 10. Santa Clara County Planning Collaborative Regional resource Checked Oct 18, 2026
  11. 11. California Department of Housing and Community Development (HCD) All state ADU/JADU rules used in state_baseline.md (sizes, heights, setbacks, parking, owner-occupancy, JADU, Checked Oct 18, 2026