ADU Rules in San Jose, CA (2026)
ADU rules, permit requirements, size limits, and fees for San Jose, CA. Source-cited from official municipal code.
Whether ADUs are allowed in San Jose, CA has not been confirmed — see the official source before proceeding.
Whether San Jose, CA permits accessory dwelling units (ADUs) has not been confirmed from an official source. ADUs — also called granny flats, in-law units, or secondary suites — are secondary housing units on a single-family or multifamily lot. Contact the local building department at (408) 535-3555 to verify current ADU rules before proceeding, as regulations may have changed since this data was last reviewed.
ADU Size Limits
ADU Size Limits in San Jose: Detached ADU: up to 1200 sq ft (max height: varies — see official source). Attached ADU: size varies by zoning — see official source. Junior ADU (JADU): up to 500 sq ft — must be within the existing primary dwelling or accessory structure. Detached ADU maximum 1,200 sqft per California Gov Code §66314(d)(5). JADU up to 500 sqft within existing residential structure or garage. Garage conversion ADUs limited to existing footprint plus 150 sqft for ingress/egress. San Jose Municipal Code Title 20 governs locally.
| Type | Max Size | Max Height |
|---|---|---|
| Detached ADU | 1200 sq ft · Verified May 25, 2026 · Source | See official source |
| Attached ADU | See official source | See official source |
| JADU | 500 sq ft · Verified May 22, 2026 · Source | Within existing structure |
Permit Fees
ADU Permit Fees in San Jose: Plan check fee: Varies. Building permit fee: Varies. Impact fees: None. School fees: None or N/A. Total estimated permit cost: Varies.
| Fee Type | Amount |
|---|---|
| Plan Check | Varies — typically $700–$2,800 for standard ADU based on valuation |
| Building Permit | Varies by valuation — typically $1,800–$5,500 |
| Impact Fees | None |
| School Fees | School developer fees exempt for ADUs under 500 sqft per California Government Code §66311.5(c)(3) and Education Code §17620. ADUs 500+ sqft subject to school developer fees at applicable school district rates. |
| Total Estimate | See official source |
Permit Timeline
San Jose ADU Permit Timeline: Permit timeline has not been confirmed — contact the department for current processing times. Apply through the local building department online permit portal. Phone: (408) 535-3555.
Setback Requirements
ADU Setback Requirements in San Jose: Front setback: follows zone standard. Side setback: no minimum. Rear setback: 4 feet.
Parking Requirements
Parking Requirements: Parking requirements have not been confirmed — see official source.
Restrictions & Requirements
- ADU must comply with objective Municipal Code zoning standards
- ADU cannot be sold separately from primary dwelling (except under Urban Lot Split per Gov Code §66411.7)
- ADU must have permanent foundation
- Hillside and Alquist-Priolo Fault Zone areas have additional structural requirements
- Fire sprinkler requirements apply for new ADU construction above certain thresholds
How Many ADUs Are Allowed?
Number of ADUs Allowed in San Jose: Single-family lots: not confirmed — see official source. Multifamily properties: not confirmed — see official source.
- Single-Family Lots
- See official source
- Multifamily Properties
- Up to 25% of existing units (minimum 2) as detached ADUs; 1 ADU per existing unit for internal conversions per Gov Code §66323(a)(3)
Statewide Preemption
ADU Preemption
California state law preempts local ADU rules — local governments cannot impose stricter standards.
View California preemption detailsState Law & Preemption
State Preemption: CA state law preempts local ADU restrictions. San Jose must approve compliant ADU applications by right.
Frequently Asked Questions
Can I build an ADU in San Jose?
Yes. San Jose, CA allows accessory dwelling units. On a single-family lot you can build 1 ADU + 1 JADU per single-family lot.
How big can an ADU be in San Jose?
The maximum size for a detached ADU in San Jose is 1,200 square feet. A Junior ADU (JADU) can be up to 500 square feet.
How long does it take to get an ADU permit in San Jose?
The typical ADU permit timeline in San Jose is The permitting agency shall either approve or deny the application to create or serve an accessory dwelling unit within 60 days from the date the permitting agency receives a completed application if there is an existing single-family or multifamily dwelling on the lot. Note: SJ PBCE ADU permits typically 3-6 weeks plan check; portal: https://www.sanjoseca.gov/your-government/departments-offices/planning-building-code-enforcement/building-division (operational, not codified).. Total estimated permit fees are $2,500–$8,500 total permit fees depending on size and scope.
Do I need extra parking for an ADU in San Jose?
San Jose parking rules for ADUs: No additional parking required for ADUs within one-half mile of VTA or BART transit stations. Garage/carport conversion ADUs require no replacement parking. Per California Gov Code §66322(a)(1).
Do I have to live on-site to have an ADU in San Jose?
Owner-occupancy requirement in San Jose: No additional standards, other than those provided in Section 66314, shall be used or imposed, including an owner-occupant requirement, except that a local agency may require that the property may be used for rentals of terms 30 days or longer.
Source: San Jose Municipal Code Title 20; California Government Code Chapter 13 §§66314–66333 (Stats. 2024 Ch. 7 §20). Last verified April 5, 2026. View source