ADU permits in San Jose, CA

A plain-English starting point for ADU contractors working in San Jose (Santa Clara County). This is general California guidance — it does not replace the requirements published by the city.

Short answer

Yes — every ADU (new construction, garage conversion, or a JADU within the existing home) requires building permits in California. State law (Government Code §65852.2) constrains how cities may regulate ADUs and sets a mandatory review period for a complete application, but each jurisdiction still sets its own development standards, fees, and submittal format. ADUs are generally permitted and built under a B (General Building) contractor coordinating the trades.

San Jose-specific fees, forms, and timelines are set by San José Planning, Building & Code Enforcement. Verified data — portal, fee schedule, adopted code — is sourced below.

The general picture

An Accessory Dwelling Unit (ADU) is a project type rather than a single trade — it bundles building, electrical, plumbing, and mechanical work, so it always requires permits from the local building department. California state law (Government Code §65852.2, and §65852.22 for Junior ADUs) sets a baseline framework that limits how local agencies may regulate ADUs and requires them to act on a complete ADU permit application within a state-mandated review period; the specific local development standards, fees, and submittal format are still set by each city or county. Confirm those specifics with the jurisdiction below before you file.

Typically needs a permit

  • New detached ADU
  • Garage or accessory-structure conversion
  • Junior ADU (JADU) within the existing home
  • Attached / addition-style ADU

Usually doesn't (general norm)

  • There is effectively no no-permit path for an ADU — by definition it creates a dwelling unit and requires permits
  • Only minor cosmetic work inside an already-permitted, legal ADU is treated like any existing dwelling
  • Anything that creates or converts living space requires a permit

Documents & plans generally required

Common reasons ADU applications get bounced

These are general, code-rooted patterns across California — not a San Jose rejection rate.

The inspection sequence

A typical order — the number of stops and exact sequence vary by jurisdiction and scope.

  1. 1Foundation / underground rough for new construction
  2. 2Framing, then rough electrical/plumbing/mechanical before cover
  3. 3Insulation and Title 24 / HERS verification where required
  4. 4Final inspections across trades and a final building sign-off before occupancy

Licensing — who can pull it

An ADU is generally built under a licensed B (General Building) contractor who coordinates the C-10 (electrical), C-36 (plumbing), and C-20 (HVAC) subtrades. State ADU law is statewide; the local building department is still the Authority Having Jurisdiction for the permit itself.

San Jose permit data

Sourced from public City of San Jose documents — every field carries the source URL and verification date.

Permit portal
SJPermits.org (San José Online Permit Center)

verified May 22, 2026 · source · Online permit applications, payments, and status check via SJPermits; electronic plan review through SJePlans

Adopted code edition

2025 California Building Standards Code

verified May 22, 2026 · source · 2025 California Building, Residential, Electrical, Mechanical, and Plumbing Codes; applicable to permit applications filed on or after January 1, 2026

Frequently asked questions

Do I need a permit to build an ADU in California?

Yes, always. An ADU creates a dwelling unit and requires building, electrical, plumbing, and mechanical permits. State law (Gov. Code §65852.2) limits how cities may regulate ADUs and sets a mandatory review period for a complete application, but the city is still the permitting authority. Confirm local standards with the department below.

Does a garage conversion to an ADU need a permit?

Yes. Converting a garage or accessory structure into living space is an ADU and requires permits, including fire separation, egress, and Title 24 compliance. Confirm the local process with the AHJ below.

How long does an ADU permit take in California?

California law requires local agencies to act on a complete ADU application within a state-mandated review period set by statute. The clock depends on the application being complete and on local process — confirm current timing and completeness requirements with the city's building department below. getPermit does not publish city-specific timelines it hasn't verified.

What is a JADU?

A Junior ADU (JADU) is a smaller unit, size-capped by state law, created within the walls of an existing single-family home with its own entrance. It still requires a permit and has its own state-law rules (Gov. Code §65852.22). Confirm local specifics with the department below.

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