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Cupertino ADU builders, rules and fees

Compare builders that name Cupertino in their service areas. Filter by your ADU type, then check the evidence before requesting a quote.

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

Can I build one?
Yes, up to 1,000 sq ft A detached ADU can be 850 sq ft with a studio or 1 bedroom, or 1,000 sq ft with 2 or more. Up to 800 sq ft is streamlined, with 4 ft setbacks and no parking.[1][2][3]
What will the city charge?
6 fee lines Plan check and inspection are $4,058 + $4,164 for 500 to 999 sq ft. See every fee[4]
Who builds here?
12 licensed builders Each lists Cupertino on its own site and holds an active CSLB license. See the list
See 12 builders Get quotes

The city's ADU page still says one detached ADU plus one JADU. The current code (Ord. 25-2274) allows up to 3 ADUs on a single-family lot.[1][3] Compare them

Licensed ADU builders in Cupertino

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

A service-area listing tells you where a company advertises work. It does not establish a completed Cupertino ADU, current availability or a price for your lot. Ask for a comparable local project and a written scope.

Directory records checked Oct 18, 2026. Use each builder’s service-area and CSLB links below to recheck the records before you hire.

Before you hire a Cupertino ADU builder

  1. 1. Match the contractor to the CSLB record

    Open the CSLB link on each builder card. Match the legal name and license number to your proposed contract, and review the current status, classification, bond and workers’ compensation information.

    Check a license on CSLB

  2. 2. Ask for evidence of a comparable Cupertino ADU

    Use the service-area link on the card to check the company’s claim. Ask for a Cupertino permit number and the ADU type, then check the record through the city’s permit resources. A service-area page alone is not a project reference.

    Cupertino ADU and permit resources

  3. 3. Separate plan approval from site approval

    If a builder offers a preapproved plan, compare the exact plan and vendor with Cupertino’s list below. Ask who handles the site plan, utility design and permit corrections for your parcel.

    See Cupertino’s preapproved plans

  4. 4. Compare the same written scope

    Ask each bidder to separate design and permits, foundation and site work, utility connections, construction and exclusions. Compare the same ADU size and type. Keep city, school and utility charges separate from the builder’s construction price.

    Review Cupertino ADU cost and fee lines

What Cupertino allows

  • Detached ADU, max size[1][3]

    800 sq ft streamlined; otherwise 850 sq ft (studio or 1 bed) or 1,000 sq ft (2+ bed)

  • Attached ADU, max size[3]

    Same caps, and a larger attached ADU can't exceed 50% of the main home

  • Junior ADU (inside the house)[1]

    Up to 500 sq ft, inside the house (not a garage), within the 45% floor area limit

  • Height[3]

    Streamlined detached: 18 ft, up to 20 ft near transit to match the roof pitch. Attached: 25 ft or the main home's limit, whichever is lower

  • Side and rear setbacks[2]

    4 ft side and rear for an ADU up to 800 sq ft

  • Floor area and lot coverage[2]

    ADUs up to 800 sq ft don't count toward floor area, lot coverage or open space

  • Units on a single-family lot[3]

    Streamlined: up to 3 ADUs in any mix. Non-streamlined: 3 total, no more than one of each type

  • Parking[2][3]

    None for streamlined ADUs. Otherwise 1 space only if the main home is short on parking, and none within 1/2 mile of transit or a block from car share. A converted garage doesn't need replacing

  • Owner must live on site[1]

    No for an ADU; yes for a JADU, with a deed restriction
  • The city page allows a second-story ADU only as a conversion of existing second-story space.[1]
  • A detached ADU needs its own address. ADUs can be rented but not sold separately, and not used as short-term rentals.[1]
  • HCD found the 2023 ADU ordinance (Ord. 23-2254) out of compliance in April 2025. Ord. 25-2274 followed.[5][3]
ADU rules in Cupertino drawn on a typical lot Detached ADU: up to 1,000 square feet, 4 feet from side and rear lot lines, 18 feet tall. Parking: None for up to 800 sq ft. Rear lot line Street Main house ADU up to 1,000 sq ft 18 ft tall 4 ft 4 ft Parking: none for up to 800 sq ft
Detached ADU. Not to scale.

City fees for an ADU in Cupertino

Fee lines for an ADU in Cupertino
ADU plan check $2,795 up to 499 sq ft; $4,058 for 500 to 999 sq ft[4] Resolution 26-047, effective July 1, 2026.
ADU inspection $2,975 up to 499 sq ft; $4,164 for 500 to 999 sq ft[4] ADUs of 1,000 sq ft and up have no separate ADU line.
Park land in-lieu fee $0 under 750 sq ft; at 750 sq ft and up, $15,000 or a share scaled to the main home, whichever is less[6][1]
Storm drain fee $0 under 750 sq ft[1][6] Larger ADUs may pay the per-unit Master Storm Drain Area fee.
School fees Cupertino Union SD $3.23 + Fremont Union HSD $2.15 per sq ft[7][8][1][9] The city says ADUs under 750 sq ft pay no school fees. Fremont Union HSD's own sheet exempts 500 sq ft or less. Ask both districts.
Water and sewer Not published by the city[1] The city says to ask your water provider and PG&E whether you need separate meters.
School fee rates for districts in Cupertino (2)

Cupertino Union SD (elementary) and Fremont Union HSD (high school). You pay both.[7][8]

  • Cupertino Union School District[7] $3.23/sq ft
  • Fremont Union High School District[9]500 sq ft or less is exempt. $2.15/sq ft
Total cost in Cupertino, fees plus building

How the permit works

  1. 1

    Send Planning a preliminary plan

    Email planning@cupertino.gov to check your plan against the zoning code.[1]

  2. 2

    Pick your plans

    Use your own designer or a pre-approved detached plan if your lot is in the Valley Floor zone.[10]

  3. 3

    Apply for a building permit

    Submit plans through Avolve and track the permit on Accela.[11]

  4. 4

    Plan review

    Typical review is 10 days per round, but the first review now averages 20 to 30 business days.[11]

  5. 5

    Pay fees and build

    ADU plan check and inspection are flat fees by size under Schedule D.[4]

Review time: Typical ADU review is 10 days for the first round. With high volume, the first review now averages 20 to 30 business days.[11]

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.[12]

Apply at: Avolve plan review portal

Preapproved plans

Cupertino has pre-approved detached ADU plans for parcels in the Valley Floor zone.[10]

Who qualifies: Valley Floor zone only; not in fault rupture, slope instability, hillside, liquefaction or inundation zones.

  • ADORE Homes 674 sq ft 2 bed / 1 bath
  • J. Kretschmer Architect 476 sq ft 1 bed / 1 bath
  • APEX Homes USA 495 sq ft 1 bed / 1 bath; 749 sq ft 2 bed / 2 bath; 991 sq ft 2 bed / 2 bath
  • Basically Homes (VitalizeBuild Construction) 499 sq ft 1 bed / 1 bath

The city lists no vendor prices. Plan check and inspection fees still apply.

Common questions

What are the Cupertino ADU requirements?

A streamlined ADU is up to 800 sq ft with 4 ft side and rear setbacks and no parking. A detached one can be 18 ft tall. You need a building permit.[2][3][1]

How big can an ADU be in Cupertino?

850 sq ft with a studio or 1 bedroom, or 1,000 sq ft with 2 or more bedrooms. ADUs up to 800 sq ft skip the floor area and lot coverage limits. A junior ADU is up to 500 sq ft.[1][2]

Do I need parking for an ADU in Cupertino?

Not for a streamlined ADU. A larger one needs 1 space only if the main home is short on parking, and none within 1/2 mile of transit.[2][3]

How much is the Cupertino ADU permit cost?

For 500 to 999 sq ft, ADU plan check is $4,058 and inspection is $4,164. ADUs under 750 sq ft pay no park or storm drain fees. School fees go to Cupertino Union and Fremont Union HSD.[4][1][7][8]

How long does a Cupertino ADU permit take?

Typical review is 10 days per round, but the first review now averages 20 to 30 business days.[11]

Nearby cities

What we couldn't confirm

  • Height and unit counts come from a code mirror (GoCodebook); the official code host blocked automated reads.
  • The city's ADU page is partly out of date against Chapter 19.112.
  • Water and sewer providers and their connection fees not confirmed.
  • No published total; ADUs of 1,000 sq ft and up have no flat ADU fee line.
  • Construction tax amount not recorded.

Sources

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

  1. 1. City of Cupertino Sizes 850/1,000 Checked Oct 18, 2026
  2. 2. City of Cupertino <=800 sf exempt from FAR/lot coverage Checked Oct 18, 2026
  3. 3. GoCodebook (third-party mirror) Unit counts, sizes, heights, setbacks, impact fee <750 exemption Checked Oct 18, 2026
  4. 4. City of Cupertino ADU plan check $2,795/$4,058 and inspection $2,975/$4,164 by size band Checked Oct 18, 2026
  5. 5. California HCD Ord Checked Oct 18, 2026
  6. 6. City of Cupertino Park land in-lieu for ADU 750 SF+: $15,000 or proportional, whichever less Checked Oct 18, 2026
  7. 7. Cupertino Union SD $3.23/sq ft residential eff Checked Oct 18, 2026
  8. 8. Fremont Union HSD All Other Residential $2.15 (Cupertino area) / $2.06 (Sunnyvale area) Checked Oct 18, 2026
  9. 9. Fremont Union HSD $2.15 (Cupertino area) / $2.06 (Sunnyvale area) eff Checked Oct 18, 2026
  10. 10. City of Cupertino Four vendors with plan sizes Checked Oct 18, 2026
  11. 11. City of Cupertino Accela/Avolve portals Checked Oct 18, 2026
  12. 12. 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