Bostonia, CA Accessory Structures: ADU Rules (2026)
ADU rules in Bostonia, CA, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.
Key Facts
- Authority
- San Diego County (unincorporated)
- County section
- Zoning Ordinance Sec. 6156
- State law
- Gov. Code Sec. 66314
- Setback
- 4 ft side and rear
- Owner-occupancy
- Not required
Summary
Bostonia is unincorporated San Diego County, so accessory dwelling units follow the County Zoning Ordinance (Sec. 6156.x) as constrained by California ADU law. The County no longer requires owner-occupancy; a detached ADU up to 1,200 sq ft is allowed by ministerial permit with 4-foot side/rear setbacks.
Local agencies are prohibited from requiring... front setbacks, and minimum lot size... that does not permit at least an 800 square foot accessory dwelling unit with four-foot side and rear yard setbacks to be constructed.
Full Breakdown
Because Bostonia has no city government, ADUs are approved by County Planning & Development Services under Zoning Ordinance Sec. 6156 and California Gov. Code Sec. 66314. Attached ADUs are capped at 50% of the primary home's floor area up to 1,200 sq ft; the County must permit at least an 800 sq ft detached unit with 4-foot side and rear setbacks. One parking space is required, but it is waived if the ADU is within a half-mile of transit. Owner-occupancy cannot be required. Applications are ministerial and must be approved or denied within 60 days.
Violations & Fines
Building an ADU without permits is a zoning/building violation abatable by County code enforcement; unpermitted work must be permitted retroactively or removed, with possible fees.
Frequently Asked Questions
Does Bostonia have its own ADU rules?
Do I have to live on the property?
Sources & Official References
Other rules in Bostonia
How Bostonia compares: Easiest Cities to Build an ADU·California rules heatmap·Compare Bostonia to another location·View the California accessory structures overview
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ADU Rules in Nearby Cities
How other cities in San Diego County handle adu rules.