What's Required in San Jose
- Up to 3 ADUs allowed on single-family lots (max 2 detached)
- Detached ADUs are limited to a 16-foot maximum height
- Minimum 4-foot rear and side setbacks required
- No additional parking required within half a mile of public transit
- Full interior build (kitchen, bath, utilities) must meet 2025 CA Residential Code
- Pre-approved ADU plans are available to reduce design and permitting time
How Much Does an ADU Permit Cost in San Jose?
Budget $1,500–$15,000 for the San Jose permit itself (valuation-based), issued by the San José Department of Planning, Building and Code Enforcement — but treat that as the entry fee, not the total. ADUs are full dwelling units, so the permit stack usually includes building, electrical, plumbing, and mechanical trade permits, plus plan review. One local note: fees vary by size; units under 750 sq. ft. are exempt from parkland and school impact fees. Get an itemized fee estimate from the department before finalizing your budget; the spread between a simple conversion and a new detached build is wide.
ADU Size Limits and Zoning Rules in San Jose
Before drawing plans, check the two gates that sink most ADU projects: size and zoning. Size ceilings vary by lot and ADU type (attached, detached, or conversion), so confirm your specific configuration. Other recorded conditions: no additional parking required within half a mile of public transit. Setbacks, height limits, and utility connections layer on top of those rules. The San José Department of Planning, Building and Code Enforcement can confirm what your specific lot allows — worth doing before you pay for architectural drawings rather than after.
How to Get a ADU Permit in San Jose
Step 1: Zoning Verification
Check your property lot size and zoning setbacks for ADU eligibility.
Step 2: Plan Selection
Select a city pre-approved plan or hire a professional for custom plans.
Step 3: SJePlans Submission
Upload architectural and structural drawings to the SJePlans portal.
Step 4: Plan Review
Standard review takes 4–8 weeks for most ADU projects.
Step 5: Inspection Series
Schedule the full sequence: Foundation, Framing, Rough MEP, Insulation, and Final.