Question 1

What are the San Diego County ADU requirements for properties in unincorporated areas?

Accepted Answer

San Diego County ADU requirements allow one ADU and one JADU on residentially zoned lots with an existing or proposed single-family dwelling in unincorporated areas, following objective standards that align with state law for size, setbacks, and parking.
• Properties must be confirmed unincorporated via the County map or Property Summary Report using your APN.
• Multifamily properties qualify for conversions of non-habitable space (up to 25% of units) plus detached ADUs.
• A building permit is always required; pre-approved County plans can speed the process.

Official sources:
https://www.sandiegocounty.gov/pds/bldg/adu.html
https://www.sandiegocounty.gov/content/dam/sdc/pds/zoning/formfields/PDS-PLN-611.pdf

Question 2

How do I check San Diego County zoning to see if an ADU is allowed on my lot?

Accepted Answer

Use the San Diego County Property Summary Report tool with your Assessor’s Parcel Number (APN) to instantly view zoning, allowable uses, and ADU eligibility for unincorporated properties.
• Only residential or mixed-use zones with an SFD qualify under current rules.
• Contact PDS for site-specific constraints like slopes, septic, or fire zones.

Official sources:
https://publicservices.sandiegocounty.gov/CitizenAccess/Report/ReportParameter.aspx?module=LUEG-PDS&reportID=2844&reportType=LINK_REPORT_LIST
https://www.sandiegocounty.gov/pds/bldg/adu.html

Question 3

What are the current San Diego County ADU size limits for attached vs detached units?

Accepted Answer

In unincorporated San Diego County, detached ADUs are limited to 1,200 sq ft maximum, while attached ADUs are limited to 50% of the primary SFD’s floor area or 1,200 sq ft (whichever is less), with exceptions allowing up to 850–1,000 sq ft for smaller configurations regardless of the 50% rule; JADUs max out at 500 sq ft.
• Conversions of existing structures have no new size cap beyond building code.
• All measurements use interior dimensions.

Official sources:
https://www.sandiegocounty.gov/content/dam/sdc/pds/zoning/formfields/PDS-PLN-611.pdf
https://www.sandiegocounty.gov/content/dam/sdc/pds/bldg/adu_info/COSD_ADU_Handbook.pdf

Question 4

What are the San Diego County ADU setbacks for new construction in unincorporated areas?

Accepted Answer

San Diego County requires a minimum 4-foot side and rear setback for newly constructed ADUs (in addition to any fire safety setbacks), while front setbacks follow the underlying zoning district; conversions of existing permitted structures generally retain their current setbacks.
• Corner lots require 4 ft from exterior side yard.
• Front-yard encroachments are possible for ADUs ≤800 sq ft under state law if needed.

Official sources:
https://www.sandiegocounty.gov/content/dam/sdc/pds/zoning/formfields/PDS-PLN-611.pdf
https://www.hcd.ca.gov/sites/default/files/docs/policy-and-research/adu-handbook-update.pdf

Question 5

Do San Diego County ADU rules require parking spaces in unincorporated areas?

Accepted Answer

San Diego County generally requires one parking space per ADU, which can be tandem or in a driveway, but provides exemptions if the site is within ½ mile of public transit, in a historic district, or for certain conversions and JADUs; no replacement parking is required when converting or demolishing a garage.

Official sources:
https://www.sandiegocounty.gov/content/dam/sdc/pds/zoning/formfields/PDS-PLN-611.pdf
https://www.sandiegocounty.gov/content/dam/sdc/pds/bldg/adu_info/COSD_ADU_Handbook.pdf

Question 6

Can I build a San Diego County ADU in the front yard under unincorporated zoning rules?

Accepted Answer

Yes, San Diego County ADU guidelines allow front-yard setback encroachment for units 800 sq ft or smaller when zoning would otherwise prevent construction, provided fire access and other safety standards are met and supporting evidence is submitted.

Official sources:
https://www.sandiegocounty.gov/pds/bldg/adu.html
https://www.hcd.ca.gov/sites/default/files/docs/policy-and-research/adu-handbook-update.pdf

Question 7

What are San Diego County ADU guidelines for converting a garage or existing structure?

Accepted Answer

Conversions of existing permitted accessory structures or portions of the primary residence into an ADU in unincorporated San Diego County are encouraged and typically exempt from new setbacks, height, or lot coverage standards (except fire and building code requirements); additions are limited to 150 sq ft for ingress/egress.

Official sources:
https://www.sandiegocounty.gov/content/dam/sdc/pds/zoning/formfields/PDS-PLN-611.pdf
https://www.sandiegocounty.gov/pds/bldg/adu.html

Question 8

How many ADUs are allowed on multifamily properties under San Diego County rules?

Accepted Answer

Unincorporated San Diego County currently allows conversion of non-habitable spaces into ADUs (up to 25% of existing units) and up to two detached ADUs on multifamily lots; a pending March 4, 2026 ordinance amendment will align with state law to permit up to eight detached ADUs on lots with existing multifamily dwellings.

Official sources:
https://www.sandiegocounty.gov/content/sdc/pds/longrangeplanning/ADU-ZO.html
https://www.sandiegocounty.gov/content/dam/sdc/pds/zoning/formfields/PDS-PLN-611.pdf

Question 9

Are short-term rentals allowed for San Diego County ADUs in unincorporated areas?

Accepted Answer

No—San Diego County ADU rules prohibit rentals shorter than 30 consecutive days, consistent with state allowances for local governments to require longer-term occupancy. Official sources: https://www.sandiegocounty.gov/content/dam/sdc/pds/zoning/formfields/PDS-PLN-611.pdf | https://www.hcd.ca.gov/sites/default/files/docs/policy-and-research/adu-handbook-update.pdf

Question 10

Is owner-occupancy required for a San Diego County ADU or JADU?

Accepted Answer

Owner-occupancy cannot be required for standard ADUs under current state law (made permanent by AB 976); for JADUs in San Diego County, the owner must reside in either the primary residence or the JADU if sanitation facilities are shared (updated rules effective 2026).

Official sources:
https://www.hcd.ca.gov/sites/default/files/docs/policy-and-research/adu-handbook-update.pdf
https://www.sandiegocounty.gov/pds/bldg/adu.html

Question 11

How long does San Diego County have to approve an ADU permit application?

Accepted Answer

State law requires San Diego County (and all jurisdictions) to approve or deny a complete ADU or JADU application within 60 days; applications are deemed complete if not acted upon within 15 business days, with strong “deemed approved” provisions if deadlines are missed.

Official sources:
https://www.hcd.ca.gov/sites/default/files/docs/policy-and-research/adu-handbook-update.pdf

Question 12

Will I pay impact fees for a San Diego County ADU in unincorporated areas?

Accepted Answer

ADUs under 750 sq ft are generally exempt from impact fees in San Diego County; larger units pay proportionate fees based on square footage relative to the primary dwelling. The County’s prior ADU fee waiver trial ended January 9, 2024.

Official sources:
https://www.sandiegocounty.gov/pds/bldg/adu.html
https://www.hcd.ca.gov/sites/default/files/docs/policy-and-research/adu-handbook-update.pdf

Question 13

What happens if I have an unpermitted ADU built before 2020 in San Diego County?

Accepted Answer

AB 2533 provides a streamlined legalization pathway for unpermitted ADUs/JADUs constructed before January 1, 2020 in unincorporated San Diego County, provided health, safety, and building standards are addressed; the County offers checklists and third-party inspection options.

Official sources:
https://www.sandiegocounty.gov/pds/bldg/adu.html
https://www.hcd.ca.gov/sites/default/files/docs/policy-and-research/adu-handbook-update.pdf

Question 14

Can I sell my San Diego County ADU separately from the main house?

Accepted Answer

Currently, ADUs in unincorporated San Diego County are not sold separately, but the County Board of Supervisors is scheduled to consider a local program on March 4, 2026 enabling separate conveyance under AB 1033 criteria (including possible right of first refusal).

Official sources:
https://www.sandiegocounty.gov/content/sdc/pds/longrangeplanning/ADU-ZO.html

Question 15

Where can I find pre-approved ADU plans for San Diego County unincorporated properties?

Accepted Answer

San Diego County offers pre-approved standard ADU building plans (approximately 85% complete) for detached units that can be adapted for unincorporated projects—download them directly from the PDS website and complete project-specific details.

Official sources:
https://www.sandiegocounty.gov/content/sdc/pds/bldg/adu_plans.html

Question 16

What are the City of San Diego ADU setbacks compared to County rules?

Accepted Answer

In the City of San Diego, ADU setbacks for new construction are generally a minimum of 4 feet side and rear (especially for units over 16 feet tall adjacent to residential uses or in Very High Fire Hazard Severity Zones), while conversions follow existing setbacks—differing from County rules primarily in coastal overlay timing and fire-specific requirements.

Official sources:
https://www.sandiego.gov/development-services/forms-publications/information-bulletins/400

Question 17

Is parking required for ADUs in the City of San Diego?

Accepted Answer

No parking is required for ADUs in the City of San Diego outside the Coastal Overlay Zone; within the Coastal Overlay, parking is only mandated in specific Beach Impact Areas outside transit priority zones, with broad exemptions.

Official sources:
https://www.sandiego.gov/development-services/forms-publications/information-bulletins/400

Question 18

How many ADUs can I build under City of San Diego rules and the density bonus program?

Accepted Answer

The City of San Diego allows a base ADU plus JADU on single-family lots, with additional units available through the ADU Home Density Bonus Program (lot-area-based maximums, e.g., 4–6 total units depending on size, with affordability requirements for bonuses).

Official sources:
https://www.sandiego.gov/development-services/forms-publications/information-bulletins/400

Question 19

Do coastal properties in San Diego County or City face extra ADU regulations?

Accepted Answer

Yes—coastal ADUs in both the County and City of San Diego may require a Coastal Development Permit and must comply with the Local Coastal Program; many City updates (including density bonus enhancements) are not yet fully effective in the Coastal Overlay Zone pending final certifications. Official sources: https://www.sandiego.gov/development-services/forms-publications/information-bulletins/400 | https://www.hcd.ca.gov/sites/default/files/docs/policy-and-research/adu-handbook-update.pdf

Question 20

Where can I get the latest official San Diego County ADU handbook and forms?

Accepted Answer

Download the County's dedicated ADU Handbook and all required forms directly from the PDS website for the most current unincorporated area guidance, including septic, fire, and stormwater considerations. Official sources: https://www.sandiegocounty.gov/pds/bldg/adu.html | https://www.sandiegocounty.gov/content/dam/sdc/pds/bldg/adu_info/COSD_ADU_Handbook.pdf

Topic	San Diego County (Unincorporated)	City of San Diego (City Limits)
Regulating Authority	County Planning & Development Services (PDS) for unincorporated areas only.	City Development Services per San Diego Municipal Code & Info Bulletin 400 (Jan 2026).
ADU Eligibility	Residentially zoned lots with existing or proposed single-family dwelling (SFD).	Zones permitting residential uses; check ZAPP portal.
Number Allowed (Single-Family)	1 ADU + 1 JADU (multifamily: conversions ≤25% + up to 2 detached; pending amendment may allow up to 8 detached per state law).	Base: 1 ADU (attached/detached/conversion) + 1 JADU; plus density bonus program (lot-size caps, e.g., up to 4–6 total).
Max Size	Detached: 1,200 sq ft; Attached: 50% of SFD or 1,200 sq ft max (exceptions for smaller units); JADU: 500 sq ft.	ADU: 1,200 sq ft max (min 150 sq ft); JADU: 500 sq ft.
Setbacks	New ADUs: 4 ft side/rear (plus fire); front per zone; conversions keep existing.	Conversions: existing; New: min 4 ft side/rear (especially >16 ft height or fire hazard zones); front per zone or 4 ft min.
Parking	1 space per ADU (tandem/driveway OK); exemptions for transit (½ mile), historic districts; no replacement for garage conversions.	No parking required outside Coastal Overlay Zone; limited requirements in specific Beach Impact Areas with exemptions.
Owner-Occupancy	Not required for ADUs (state law); required for JADUs (owner in primary or JADU if shared sanitation).	Not required for ADUs; required for JADUs (with exceptions).
Rental / Short-Term	No rentals <30 days.	ADUs: no lease <31 days; JADUs: >30 days, no short-term residential occupancy.
Permitting Timeline	60 days ministerial after complete application (statewide).	60 days ministerial (statewide); Coastal Development Permit may apply in overlay.
Fees / Impact	Impact fees exempt <750 sq ft; proportionate above; prior waiver program ended Jan 2024.	Per City fee schedule; state limits apply.
Upcoming Changes	Board of Supervisors hearing March 4, 2026 on ordinance amendment (clarifications, multifamily increases, separate sale program per AB 1033).	Some density bonus & other updates pending full Coastal Commission certification.

San Diego County Regulations & Zoning

Key Facts Snapshot (Updated March 2026)

Rent Rates In San Diego County

FAQs: San Diego County ADU Requirements, Laws & Guidelines (2026)

Build Ready Plan For San Diego County

Model 13 – 1188SF, 3 Bed and 2 Bath

Model 12: 950SF, 2 Bed and 2 Bath