ADU Rules: Bostonia vs Oceanside
How do adu rules rules compare between Bostonia, CA and Oceanside, CA?
Bostonia has fewer restrictions than Oceanside.
Bostonia, CA
San Diego County
Bostonia is an unincorporated CDP in San Diego County (adjacent to El Cajon) governed by the San Diego County Zoning Ordinance §6156 (Accessory Dwelling Units and Junior Accessory Dwelling Units), not a city ordinance. The County allows one ADU plus one JADU on single-family lots; non-conforming multifamily complexes may have up to two detached ADUs OR conversion ADUs created within the existing complex.
View full Bostonia rules →Oceanside, CA
San Diego County
Oceanside allows ADUs per state mandate (Gov Code §65852.2) and local Zoning Ordinance Section 3006. Detached ADUs up to 1,200 sq ft. Height 16 ft standard, 18 ft near transit, 20 ft with matching roof pitch. 4-foot side/rear setbacks.
View full Oceanside rules →Key Facts Comparison
| Fact | Bostonia | Oceanside |
|---|---|---|
| Governing Code | San Diego Co. Zoning Ord. §6156 | - |
| Max Attached ADU | 1,200 sq ft (50% rule applies) | - |
| Max Detached ADU | 1,200 sq ft | - |
| Max JADU | 500 sq ft | - |
| Side/Rear Setback | 4 ft minimum + fire setbacks | - |
| Max Size | - | 1,200 sq ft detached |
| Height | - | 16 ft (18-20 near transit) |
| Setbacks | - | 4 ft side/rear |
| Code | - | OZO §3006 |
Highlighted rows indicate differences between cities.
Bostonia FAQ
Who regulates ADUs in Bostonia?
Bostonia is unincorporated San Diego County, so the San Diego County Department of Planning & Development Services regulates ADUs under Zoning Ordinance §6156, not the City of El Cajon.
How big can my Bostonia ADU be?
Under §6156, detached ADUs may be up to 1,200 sq ft and attached ADUs up to 50% of the primary dwelling capped at 1,200 sq ft (at least 800 sq ft must always be allowed). JADUs are capped at 500 sq ft within the existing single-family dwelling.
Can a Bostonia multifamily complex add ADUs?
Yes, but only one approach per property: up to two detached ADUs OR conversion ADUs created within the existing multifamily complex, not both, per §6156.
Oceanside FAQ
Can I build an ADU on my property in Oceanside?
Oceanside allows ADUs per state mandate (Gov Code §65852.2) and local Zoning Ordinance Section 3006. Detached ADUs up to 1,200 sq ft. Height 16 ft standard, 18 ft near transit, 20 ft with matching roof pitch. 4-foot side/rear setbacks.
What are the size limits for an accessory dwelling unit in Oceanside?
Max Size: 1,200 sq ft detached. Height: 16 ft (18-20 near transit). Setbacks: 4 ft side/rear. Code: OZO §3006.
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