1. Feasibility And Site Fit
A quick property screen to validate lot constraints, utility path, and ADU strategy before you spend on full design. See the full ADU feasibility study guide.
Free Planning Resource
ADU Handbook for Unincorporated San Diego County (Adapted from the County)
Last reviewed June 30, 2026
This handbook is adapted from the County of San Diego's Accessory Dwelling Unit Handbook (April 2024). We redesigned the layout, replaced the photos with our own illustrations, and added short tips. Most of the text and all of the rules are the County's, and they apply to unincorporated San Diego County. The County's original is the official version.
An adapted copy of the County handbook for property owners in unincorporated San Diego County.
Unincorporated San Diego County
Adapted from the County
County text and County rules
San Diego ADU Guide
ADU Handbook
Adapted from the County of San Diego
Read The Full Handbook Online (HTML Version)
This is the HTML version of the handbook so it can be read in the browser.
Direct HTML URL: View the handbook source page
Illustrations in this handbook are AI-generated and are not real projects.
What Is Inside
2. Permit Sequence
A step-by-step permit roadmap showing what comes first, who prepares what, and where projects most commonly lose momentum. See the ADU permitting guide.
ADU Handbook for Unincorporated San Diego County
The handbook below is an adapted copy of the County of San Diego's April 2024 ADU handbook. It is for property owners in unincorporated San Diego County. Most of the text and all of the rules are the County's.
How To Use This Guide
- Read it as the County's handbook, in a redesigned layout.
- The rules apply to unincorporated San Diego County, not to every city in the county.
- Use the County PDF linked above when you need the official version.
- Use the feasibility and permitting guides on this site when you want a shorter explanation of those steps.
What The County Handbook Covers
- What an accessory dwelling unit is
- County standards for a unit on a property in unincorporated San Diego County
- Steps, requirements, and questions the County walks through
- Where to confirm the current process on the County's own pages
Related ADU Guides
Use these pages alongside the handbook for property-specific detail.
- ADU feasibility studies: confirm zoning, utilities, and buildable area before design
- San Diego ADU permitting: step-by-step permit process, plan-check, and inspections
- ADU cost guide: complete budget framework including site work, utilities, and permits
- Detached ADUs: backyard homes for rental income or family housing
- Garage conversion ADUs: converting an existing garage into livable space
- Attached ADUs: additions connected to the primary home
- JADUs: compact units within a single-family residence
- San Diego ADU rules: current regulations, setbacks, and official sources
Important Note
This handbook is adapted from the County of San Diego's Accessory Dwelling Unit Handbook (April 2024). We redesigned the layout, replaced the photos with our own illustrations, and added short tips. Most of the text and all of the rules are the County's, and they apply to unincorporated San Diego County. The County's original is the official version.
This handbook is an information guide. It is not legal advice, financial advice, or an offer to design or build. Always verify current County and State requirements before final permit submittal.