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Building an ADU in Milpitas, CA

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

Can I build one?
Yes, up to 1,200 sq ft Detached ADUs can be 1,200 sq ft and 16 ft tall. You need 1 parking space unless a state exemption applies, such as being within a 1/2 mile walk of transit.[1]
What will the city charge?
$5,255 ADU, 800 sq ft (city estimate, minimum). School and utility fees extra. See every fee[2]
Who builds here?
8 licensed builders Each lists Milpitas on its own site and holds an active CSLB license. See the list
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Licensed ADU builders in Milpitas

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 Milpitas allows

  • Detached ADU, max size[1]

    1,200 sq ft (150 sq ft minimum)

  • Attached ADU, max size[1]

    50% of the main home, but 800 sq ft is always allowed

  • Junior ADU (inside the house)[1]

    Up to 500 sq ft

  • Height[1]

    Detached: 16 ft, or 18 ft within 1/2 mile of transit; +2 ft to match the roof pitch. Attached: 25 ft or the zone height, whichever is lower

  • Side and rear setbacks[1]

    4 ft side and rear; 8 ft front

  • Units on a single-family lot[1]

    1 attached ADU + 1 detached ADU + 1 JADU

  • Parking[1]

    1 space per ADU; none within a 1/2 mile walk of transit, inside existing space, or under other state exemptions. None for a JADU. A converted garage doesn't need replacing

  • Owner must live on site[1][3]

    No for an ADU. Yes for a JADU, unless it has its own bathroom

  • Permit path[1]

    Building permit only. The city must act within 60 days, or 30 days with a pre-approved plan
  • Free ADU Monday video calls put Building, Planning and Land Development staff on one call.[4]
  • Lot coverage, floor area and open space rules can't block an ADU up to 800 sq ft with 4 ft side and rear setbacks.[1]
  • Pre-approved plans over 800 sq ft need a Minor Site Development Permit.[5]
ADU rules in Milpitas drawn on a typical lot Detached ADU: up to 1,200 square feet, 4 feet from side and rear lot lines, 16 feet tall. Parking: 1 space, with state exemptions. Rear lot line Street Main house ADU up to 1,200 sq ft 16 ft tall 4 ft 4 ft Parking: 1 space, with state exemptions
Detached ADU. Not to scale.

City fees for an ADU in Milpitas

Minimum totals from the city's ADU Permit Fee Estimate (FY 2025-26 fees, dated 6/11/2026). They cover building fees plus minimum planning and land development review, for any new ADU of that size. Not included: school fees over 500 sq ft, utility connections, a possible $703 fire sprinkler review and a $709 new address. At 500 sq ft the estimate is $4,048.31.[2]

ADU, 1,200 sq ft

$6,931

ADU, 1,000 sq ft

$6,060

ADU, 800 sq ft

$5,255

Fee lines for an ADU in Milpitas
Plan review and inspection, scaled by size 500 sq ft: $1,390.08 + $1,945.85; 1,000 sq ft: $2,265.84 + $2,918.77[7] Plus a 3.8% permitting automation fee, a 5% community planning fee and state fees. Schedule effective Aug 3, 2026.
Planning and land development review Planning $275 an hour (half-hour minimum); land development $231 an hour (1-hour minimum)[7]
No-fee ADU permits The city covers permit fees for eligible ADUs, about $5,000 on average[6] A limited-time program. The city's notice is undated, so ask adu@milpitas.gov if it is still open.
Park and impact fees No park fee for ADUs; no impact fees under 750 sq ft[2][1] ADUs of 750 sq ft or more pay other impact fees in proportion to the main home.
School fees (Milpitas Unified) $5.17 per sq ft on the whole ADU at 500 sq ft and up[8]
Water connection (City of Milpitas) $1,910 × (ADU sq ft ÷ main home sq ft)[2] Only when a new connection is needed or requested.
Sewer and treatment plant connection (City of Milpitas) $1,908 sewer + $880 treatment plant, each × (ADU sq ft ÷ main home sq ft)[2] Only when a new connection is needed or requested.
Fire sprinkler review and new address $703 sprinkler review if it applies; $709 new address request[2]
School fee rates for districts in Milpitas (1)

Milpitas Unified is a K-12 district, so you pay one school fee.[8]

  • Milpitas Unified School District[8]ADUs of 500 sq ft or more are charged on their entire area. $5.17/sq ft
Total cost in Milpitas, fees plus building

How the permit works

  1. 1

    Book a free ADU Monday consultation

    Building, Planning and Land Development staff answer questions on one video call.[4]

  2. 2

    Pick your plans

    Use your own designer, or buy a pre-approved detached plan for a faster review.[5]

  3. 3

    Submit online

    Apply through Online Plan Submittal. An ADU that meets the standards needs only a building permit.[5][1]

  4. 4

    Plan review

    The target is 20 business days for the first review and 15 for each resubmittal.[9]

  5. 5

    Pay fees, build and pass inspections

    Inspection fees follow the building fee schedule. ADUs of 500 sq ft and up also pay Milpitas Unified.[7][8]

Review time: The city targets 20 business days for the first review of an attached or detached ADU, 15 for resubmittals.[9]

State deadline: City code says Milpitas must act within 60 days of a complete application, or 30 days with a pre-approved plan.[1]

Apply at: Online Plan Submittal

Preapproved plans

Milpitas has a pre-approved detached ADU program. Plan review is billed by the hour and can be up to 50% faster.[5]

Who qualifies: Not in the Hillside Building Code area, not in a flood zone unless the plan has a flood option, not in an easement, and no changes to the plan. Plans over 800 sq ft need a Minor Site Development Permit.

  • Adore Homes 667 sq ft 2 bed / 2 bath
  • Aligcus 800 sq ft 2 bed / 2 bath (2 options); 1,000 sq ft 3 bed / 2 bath (2 options)
  • SFBAYADU 747 sq ft 2 bed / 1 bath
  • Basically Homes (VitalizeBuild Construction) 499 sq ft 1 bed / 1 bath (2022 codes)

The city publishes no prices for these plans.

Common questions

What are the ADU requirements in Milpitas?

A detached ADU can be 1,200 sq ft and 16 ft tall, with 4 ft side and rear setbacks and an 8 ft front setback. A single-family lot can have 1 attached ADU, 1 detached ADU and 1 JADU.[1]

How big can an ADU be in Milpitas?

Up to 1,200 sq ft for a detached ADU. An attached ADU can be half the main home, and 800 sq ft is always allowed. A junior ADU is up to 500 sq ft.[1]

How much is the Milpitas ADU permit cost?

The city's own estimate is $4,048.31 at 500 sq ft, $5,255.11 at 800 sq ft and $6,930.75 at 1,200 sq ft, as minimums. School fees and utility connections are extra. A limited-time city program may cover permit fees for eligible ADUs.[2][6]

Do I need parking for an ADU in Milpitas?

Usually 1 space. You need none within a 1/2 mile walk of transit, when the ADU is inside existing space, or under other state exemptions. A junior ADU needs none.[1]

How long does an ADU permit take in Milpitas?

The city targets 20 business days for the first review. City code requires a decision within 60 days, or 30 days with a pre-approved plan.[9][1]

Nearby cities

What we couldn't confirm

  • End date and eligibility of the no-fee ADU permit program are not on a dated official page.
  • The fee estimate uses FY 2025-26 fees; a total under the Aug 3, 2026 schedule is not published.

Sources

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

  1. 1. City of Milpitas Section C.10.030 ADU/JADU standards: sizes, heights, setbacks, parking, counts, 60/30-day review, impact fees Checked Oct 18, 2026
  2. 2. City of Milpitas Office of Building Safety Total permit fee estimates by sf ($1,271.37 at 100 sf to $6,930.75 at 1,200 sf) Checked Oct 18, 2026
  3. 3. City of Milpitas Planning Links MMC XIII-C.10.030, fee estimate PDF, JADU deed restriction Checked Oct 18, 2026
  4. 4. City of Milpitas Building Safety Hub: ADU Monday, resources, pre-approved program, Safe ADU legalization Checked Oct 18, 2026
  5. 5. City of Milpitas Eligibility Checked Oct 18, 2026
  6. 6. City of Milpitas No-fee ADU permits: Office of Building Safety covers permit fees for eligible ADU projects (new and legalizati Checked Oct 18, 2026
  7. 7. City of Milpitas Office of Building Safety Square-footage plan review/inspection table for SFR/duplex/additional dwelling units Checked Oct 18, 2026
  8. 8. Milpitas Unified School District Residential $5.17/sf Checked Oct 18, 2026
  9. 9. City of Milpitas Office of Building Safety Attached/detached ADU target 20 business days initial, 15 resubmittal Checked Oct 18, 2026