ADU Rules: Bostonia vs El Cajon
How do adu rules rules compare between Bostonia, CA and El Cajon, CA?
Bostonia has fewer restrictions than El Cajon.
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 →El Cajon, CA
San Diego County
El Cajon allows one ADU plus one JADU per single-family lot. Maximum 1,200 sq ft but not larger than the primary dwelling. Setbacks of 5 ft allow 20 ft height, 4 ft allows 16 ft. El Cajon uniquely requires a sewer lateral video.
View full El Cajon rules →Key Facts Comparison
| Fact | Bostonia | El Cajon |
|---|---|---|
| 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 |
| Height at 4 ft | - | 16 ft |
| Separation | - | 6 ft from primary |
| Unique | - | Sewer lateral video |
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.
El Cajon FAQ
Can I build an ADU on my property in El Cajon?
El Cajon allows one ADU plus one JADU per single-family lot. Maximum 1,200 sq ft but not larger than the primary dwelling. Setbacks of 5 ft allow 20 ft height, 4 ft allows 16 ft. El Cajon uniquely requires a sewer lateral video.
What are the size limits for an accessory dwelling unit in El Cajon?
Max Size: 1,200 sq ft. Height at 4 ft: 16 ft. Separation: 6 ft from primary. Unique: Sewer lateral video.
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