San Diego region / California
San Diego County ADU rules
& permit guide.
For unincorporated San Diego County, Planning & Development Services provides a dwelling-unit plan library. Its six ADU options range from 600 to 1,200 sq ft and still need project-specific work.
Editorial review 2026-09-07 · View sources
The local detail to check first
Before you choose a design
These plans are approximately 85% complete. Confirm fire access, grading, utilities and any septic requirements before treating the plan library as a construction-ready package.
Local requirements at a glance
Min/max ADU size
The county library offers six ADU plans from 600 to 1,200 sq ft. This is a plan range, not a finding that every size fits your parcel.
Process
Complete the county’s dwelling-unit checklist and add the site-specific information missing from the standard drawings.
Your next three steps
- Confirm that County PDS is your permitting authority.
- Choose a plan and review the Dwelling Unit Checklist and its guidance.
- Supply the required site information and submit through the County’s permit process.
2026 state-law context
ADUs and JADUs have different occupancy rules
California generally prohibits local owner-occupancy requirements for ADUs. A narrow exception applies to certain separately sold affordable ADUs. For JADUs, owner occupancy generally applies when the bathroom is shared with the main home; separate-bathroom JADUs are treated differently under 2026 law. Check the HCD handbook and your project's permit conditions.
Older local summaries may not reflect the latest state changes. Read HCD’s March 2026 handbook, pages 32–33.
A starting point for your design
Local plan resources
County ADU plans A–F ↗
600, 800, 1,000 and 1,200 sq ft options. Plans G and H on the same page are labeled single-family dwelling only.
Questions for your first planning conversation
- Which approval path applies to my building and ADU type?
- Do easements, trees, slope, access or fire conditions affect placement?
- Which utility upgrades and agency reviews should be included in my budget?
- Are preapproved plans available, and what site work still needs review?