How to Get an ADU Permit in San Jose

Building an Accessory Dwelling Unit (ADU) in San Jose offers homeowners a strategic solution to California's housing challenges, providing opportunities for rental income, multigenerational living, or additional space. With streamlined processes and supportive policies, San Jose makes it feasible to add an ADU to your property.

What Is an ADU?

An Accessory Dwelling Unit (ADU) is a secondary, self-contained residential unit located on the same lot as a primary dwelling. Commonly referred to as granny flats, in-law units, or backyard cottages, ADUs typically include a kitchen, bathroom, and sleeping area. In San Jose, ADUs are permitted on single-family, duplex, and multifamily zoned properties, subject to specific regulations.

Step-by-Step Guide to Getting an ADU Permit in San Jose

1. Determine Eligibility

Before initiating your ADU project, assess your property's eligibility by completing the ADU Universal Checklist.

This checklist helps identify zoning requirements, size limitations, and other pertinent factors. Ensure your property is not located in restricted zones such as geohazard, flood, or Wildland-Urban Interface areas.

2. Choose Your ADU Type

San Jose recognizes several ADU types, each with distinct requirements:

Detached ADUs: Standalone units separate from the primary residence.
Attached ADUs: Units connected to the main dwelling.
Garage or Basement Conversions: Repurposing existing structures into living spaces.
Junior ADUs (JADUs): Units under 500 sq. ft., typically within the existing footprint of a single-family home.
Tiny Homes on Wheels (THOWs): Mobile units allowed only on single-family properties, subject to specific guidelines

3. Prepare Required Documentation

Gather the necessary documents to support your permit application:

Completed Forms:
- Form 310: Building Permit Application
- Form 311: Owner-Builder Acknowledgement
- Form 312: ADU Property Owner Declaration
- Form 302: Address Assignment Request
Site-Specific Plans: Detailed drawings indicating the proposed ADU's location, dimensions, and compliance with setback requirements.
Fire Flow Letter: A statement from your water utility confirming adequate fire flow at the nearest hydrant.
Title 24 Energy Compliance: Documentation demonstrating adherence to California's energy efficiency standards.
Geotechnical Report: If applicable, a report assessing soil conditions.
Inspection Checklists: Completed forms outlining inspection requirements.
Fee Payments: Proof of payment for applicable fees.

4. Submit Your ADU Permit Application

Initiate the application process through SJPermits.org.

Select the appropriate permit type and upload your documents to the SJePlans system for review. Ensure all files adhere to the city's formatting and naming conventions to avoid delays.

5. Planning Review and Approvals

City staff will conduct a thorough review of your submitted plans.This process includes:

Prescreen Review: Initial assessment to ensure completeness.
Plan Review: Detailed examination for compliance with building codes and zoning laws.
Issuance Review: Final checks before permit issuance.

Upon approval, you'll receive your building permit and approved plans via SJePlans.

6. Get Building Permits and Start Construction

With the permit in hand, commence construction. Schedule inspections at various stages to ensure compliance with approved plans.

Utilize the ADU Inspection Checklist to prepare for each inspection.

Benefits of Building an ADU in San Jose

Generates passive rental income to help offset mortgage or living expenses.
Increases property value significantly with added livable square footage.
Provides flexible housing for aging parents, adult children, or guests.
Supports San Jose’s housing goals, helping alleviate the housing shortage.
Exempt from many impact fees, making small ADUs more affordable to build.

How Much Does an ADU Permit Cost in San Jose

Permit Component	Estimated Cost
Building Permit Fees	$3,000 – $8,000+
Plan Review Fees	Included in Building Permit Fee
School Impact Fees	$4 – $5 per sq. ft. (if over 750 sq. ft.)
Parkland Dedication Fee	Varies (can be several thousand dollars)
Utility Connection Fees	$500 – $2,500+
Fire Department Review Fee	$200 – $600
Geotechnical Report (if needed)	$1,500 – $3,000
Title 24 Energy Report	$200 – $500
Total Estimated Cost	$3,500 – $15,000+

FAQ

How long does it take to get an ADU permit in San Jose?

If you're using pre-approved plans, you may get your permit in as little as 4–6 weeks. For custom designs, expect 2–3 months.

How much does it cost to get an ADU permit in San Jose?

Permitting fees range from $3,000 to $8,000 depending on size and complexity. Construction costs vary but typically start around $150,000 for a detached unit.

Do I need to provide parking for an ADU in San Jose?

In most cases, no. Especially if your home is within a half-mile of public transit or in a historic or high-density zone.

Can I build more than one ADU on my property?

Yes, if you live on a multifamily property, you may be eligible to build multiple ADUs, depending on the number of existing units.

Is a Junior ADU easier to permit?

Yes. Junior ADUs (JADUs) often have simplified requirements and can be built within the existing envelope of your home.