Skip to content
Bay Area ADU Builders
Get quotes

Building an ADU in San Jose, CA

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

Can I build one?
Yes, 800 to 1,200 sq ft 1,000 sq ft on most lots under City rules, 1,200 on lots over 9,000 sq ft, 800 under State rules. No parking required.[1]
What will the city charge?
$13,092 Average city fees for a detached ADU up to 750 sq ft, $22,312 up to 1,200 sq ft. School fees extra.[2][3]
Who builds here?
18 licensed builders Each lists San Jose on its own site and holds an active CSLB license. See the list
See 18 builders Get quotes

San José has two rulebooks. You pick City standards or State standards for the whole project and can't mix them.[1] Compare them

Licensed ADU builders in San Jose

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 San Jose allows

San José has two rulebooks. You pick City standards or State standards for the whole project and can't mix them.

  • Detached ADU, max size[1]

    City standards
    1,000 sq ft (1,200 sq ft on lots over 9,000 sq ft)
    State standards
    800 sq ft

  • Attached ADU, max size[1]

    City standards
    50% of the main home, up to 1,000 sq ft (1,200 on lots over 9,000 sq ft)
    State standards
    800 sq ft

  • Conversion of existing space[1]

    City standards
    Counts as your one ADU
    State standards
    1 conversion ADU, no size cap (+150 sq ft for entry)

  • Junior ADU (inside the house)[1]

    City standards
    Up to 500 sq ft
    State standards
    Up to 500 sq ft

  • Height[1]

    City standards
    18 ft one story, 25 ft two stories
    State standards
    18 ft (+2 ft for a pitched roof)

  • Side and rear setbacks[1]

    City standards
    0 ft first story, 4 ft second story; 6 ft from the main home
    State standards
    4 ft

  • Where on the lot[1]

    City standards
    Behind the main home or 45 ft from the front; max 40% of the rear yard
    State standards
    Can use the front setback if that's the only way to fit 800 sq ft

  • Units on a single-family lot[1]

    City standards
    1 ADU + 1 JADU
    State standards
    1 new ADU + 1 conversion ADU + 1 JADU

  • Parking[1]

    City standards
    None
    State standards
    None

  • Owner must live on site[1][4]

    City standards
    No for an ADU; yes for a JADU (deed restriction)
    State standards
    No for an ADU; yes for a JADU (deed restriction)
  • Minimum size is 150 sq ft. Two stories max under either rulebook.[1]
  • Fire access: the ADU must be within 200 ft of the curb along a 3 ft path and within 600 ft of a hydrant. If the main home has sprinklers, the ADU needs them too.[1]
  • You can build an ADU behind a house you rent out, and rent both to different people.[4]
ADU rules in San Jose drawn on a typical lot Detached ADU, City standards: up to 1,200 square feet, 4 feet from side and rear lot lines, 18 feet tall. Parking: None required. Rear lot line Street Main house ADU up to 1,200 sq ft 18 ft tall 0–4 ft 0–4 ft 6 ft apart Parking: none required
Detached ADU, City standards. Not to scale.

City fees for an ADU in San Jose

Averages of ADU permits San José issued in the last 12 months, from the city's Building Fee Estimator. Not a quote. School fees are not included.[2][3]

Detached, up to 750 sq ft

$13,092

average of 26 permits

Detached, 751 to 1,200 sq ft

$22,312

average of 20 permits

Attached, up to 750 sq ft

$10,729

average of 26 permits

Attached, 751 to 1,200 sq ft

$17,859

average of 10 permits

Junior ADU

$8,137

average of 15 permits

Fee lines for an ADU in San Jose
Building permit, plan review and inspection (fee schedule) $3,323 up to 750 sq ft; $5,151 for 751 to 1,200 sq ft[6] Modular units pay 10% less for plan review and 20% less for inspection.
Construction taxes 3.96% of valuation, plus $330 per unit[6] Valuation uses $169.09 per sq ft.
Parkland fee $0 under 750 sq ft; $1,700 to $8,900 at 750 sq ft and up, by zone[7][8]
School fees $1.36 to $5.38 per sq ft, set by your school districts[7][9][10] San José says ADUs under 750 sq ft pay none. East Side Union HSD says they do, and most districts only exempt 500 sq ft or less. Ask both of your districts before you budget.
Sewer, storm drain and treatment plant $447 sewer + $270 storm drain per lot; treatment plant $780 per unit[6] The schedule has no ADU-specific line; confirm at the counter whether these apply to your ADU.
Water service Depends on your water company[11][4] San Jose Water, Great Oaks Water, or San José Municipal Water. Separate meters are optional.
School fee rates for districts in San Jose (14)

19 districts serve San José. We list the 14 that post their fees online. You pay both your elementary and high school district unless you're in a unified district.[12]

  • San José Unified School District[13] $5.38/sq ft
  • East Side Union High School District[9]Says ADUs under 750 sq ft are not exempt; charges additions over 500 sq ft. $1.36/sq ft
  • Campbell Union High School District[14] $1.61/sq ft
  • Fremont Union High School District[15]500 sq ft or less is exempt. $2.15/sq ft
  • Campbell Union School District[16]Charges ADUs over 500 sq ft. $3.79/sq ft
  • Cambrian School District[17]Additions of 500 sq ft or less are exempt. $3.77/sq ft
  • Union School District[18]Residential under 500 sq ft is exempt; rate not published on the page. not published
  • Oak Grove School District[19]Additions of 500 sq ft or less are exempt. $3.59/sq ft
  • Franklin-McKinley School District[20]Additions of 500 sq ft or less pay no fee. $3.59/sq ft
  • Moreland School District[21] $3.35/sq ft
  • Cupertino Union School District[22] $3.23/sq ft
  • Santa Clara Unified School District[23]No fees on ADUs or additions under 500 sq ft. $5.38/sq ft
  • Evergreen School District[24]Rate not published on the page. not published
  • Berryessa Union School District[25]Rate not published on the page. not published
Total cost in San Jose, fees plus building

How the permit works

  1. 1

    Check your lot against the Universal Checklist

    Pick City or State standards. An optional planning call costs $398 an hour, 30 minutes minimum.[26]

  2. 2

    Prepare plans

    Follow Bulletin #211 and Directive B-007, or use a preapproved plan.[26]

  3. 3

    Apply on SJPermits.org and upload to SJePlans

    Prescreen, plan review, then issuance review.[26]

  4. 4

    Pay fees and get the permit

    Residual plan review, inspection fees, taxes, school and parkland fees are due at issuance.[26]

  5. 5

    Build and pass inspections

    Bulletin #213 lists the inspections. Construction debris sign-off comes before the final.[26]

Review time: About 20 business days for the first round of building review.[4]

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.[27]

Apply at: SJPermits.org

Preapproved plans

San José has preapproved detached ADU plans. If your site package is complete, the permit can be issued the same day as the plan review meeting.[28]

Who qualifies: Lots with an existing house or duplex, outside geohazard, landslide, flood and wildfire zones.

  • Acsiom Designs 746 to 991 sq ft, 2 to 3 bedrooms
  • Ca2Homes 499 sq ft 2 bed / 1 bath; 747 sq ft 2 bed / 2 bath
  • J. Kretschmer Architect 476 sq ft 1 bed; 748 sq ft 2 bed
  • LiveLarge 795 sq ft 2 bed / 2 bath
  • Orange Engineering 799 sq ft 2 bed / 2 bath

The city publishes no prices for these plans.

Common questions

How big can an ADU be in San Jose?

Under City standards a detached ADU can be 1,000 sq ft, or 1,200 sq ft on lots over 9,000 sq ft. Under State standards it's 800 sq ft. A junior ADU inside the house is up to 500 sq ft.[1]

Do I need parking for an ADU in San Jose?

No. Neither rulebook requires parking for an ADU.[1]

How much are ADU permit fees in San Jose?

The city's fee estimator averages $13,092 for a detached ADU up to 750 sq ft and $22,312 for 751 to 1,200 sq ft. School fees are extra, and parkland fees start at 750 sq ft.[2][3][7]

Do I have to live on the property?

Not for an ADU. You can rent the house and the ADU to different people. A junior ADU does require the owner to live in the main home.[1][4]

How long does the San Jose ADU permit take?

The first round of building review takes about 20 business days. With a complete preapproved-plan package, the city can issue the permit the same day as the review meeting.[4][28]

Nearby cities

What we couldn't confirm

  • The FY 2026-27 building fee schedule could not be read; fee-schedule lines use FY 2025-26 (effective Aug 11, 2025).
  • Water company connection and meter fees not recorded.
  • No ADU fee waivers found beyond the state exemption under 750 sq ft.

Sources

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

  1. 1. City of San José Building Division City vs State standards tables: sizes, heights, setbacks, counts, parking none, JADU owner occupancy Checked Oct 18, 2026 read from an archived copy of this official page
  2. 2. City of San José Estimator averages similar permits from last 12 months Checked Oct 18, 2026
  3. 3. City of San José Building Fee Estimator (New ADU results) New ADU estimates: detached 0-750 $13,092 Checked Oct 18, 2026
  4. 4. City of San José First building review typically 20 business days Checked Oct 18, 2026
  5. 5. City of San José ADU landing page Checked Oct 18, 2026
  6. 6. City of San José Building Division ADU 0-750 sf: $454/$1,137/$1,732 Checked Oct 18, 2026 read from an archived copy of this official page
  7. 7. City of San José Fees by ADU size per Building Fee Schedule Checked Oct 18, 2026
  8. 8. City of San José Per-unit ADU parkland fee by MLS zone ($1,700-$8,900) Checked Oct 18, 2026 read from an archived copy of this official page
  9. 9. East Side Union HSD Residential $1.36/sf eff Checked Oct 18, 2026
  10. 10. CA DGS / Office of Public School Construction (State Allocation Board) 2026 maximum Level I residential $5.38/sf (2024: $5.17 Checked Oct 18, 2026
  11. 11. City of San José Water providers: San Jose Water, Great Oaks Water, San José Municipal Water System Checked Oct 18, 2026 read from an archived copy of this official page
  12. 12. City of San José Building Division School fee process Checked Oct 18, 2026 read from an archived copy of this official page
  13. 13. San José Unified School District Residential $5.38/sf Checked Oct 18, 2026
  14. 14. Campbell Union HSD $1.61/sq ft eff Checked Oct 18, 2026
  15. 15. Fremont Union HSD $2.15 (Cupertino area) / $2.06 (Sunnyvale area) eff Checked Oct 18, 2026
  16. 16. Campbell Union SD Residential & ADU $3.79/sq ft Checked Oct 18, 2026
  17. 17. Cambrian School District Eff Checked Oct 18, 2026
  18. 18. Union School District 70/30 split with CUHSD Checked Oct 18, 2026 read from an archived copy of this official page
  19. 19. Oak Grove School District Residential $3.59/sf effective 8/17/2026 Checked Oct 18, 2026
  20. 20. Franklin-McKinley School District $3.45/sf before and $3.59/sf on/after 10/24/2026 (Res Checked Oct 18, 2026
  21. 21. Moreland School District Residential $3.35/sf Checked Oct 18, 2026
  22. 22. Cupertino Union SD $3.23/sq ft residential eff Checked Oct 18, 2026
  23. 23. Santa Clara Unified School District Residential $5.38/sf effective 8/24/2026 Checked Oct 18, 2026
  24. 24. Evergreen School District Payment process only Checked Oct 18, 2026 read from an archived copy of this official page
  25. 25. Berryessa Union School District Links 4/3/2024 developer fee study and May 2024 hearing notice Checked Oct 18, 2026 read from an archived copy of this official page
  26. 26. City of San José 6-step process (checklist, plans, SJPermits, SJePlans, prescreen/plan review/issuance, inspections) Checked Oct 18, 2026
  27. 27. 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
  28. 28. City of San José 5 approved vendors + 7 pending Checked Oct 18, 2026