ADU Rules: El Cajon vs Fallbrook
How do adu rules rules compare between El Cajon, CA and Fallbrook, CA?
El Cajon and Fallbrook have similar restriction levels.
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 →Fallbrook, CA
San Diego County
San Diego County allows Accessory Dwelling Units (ADUs) on residential properties in unincorporated areas per state law and the County ADU Handbook. Detached ADUs up to 1,200 sq ft. Must maintain 4-foot side/rear setbacks. ADUs up to 800 sq ft are exempt from lot coverage limits.
View full Fallbrook rules →Key Facts Comparison
| Fact | El Cajon | Fallbrook |
|---|---|---|
| Max Size | 1,200 sq ft | - |
| Height at 4 ft | 16 ft | - |
| Separation | 6 ft from primary | 6 ft from other structures |
| Unique | Sewer lateral video | - |
| Max Size (Detached) | - | 1,200 sq ft |
| Side/Rear Setback | - | 4 feet minimum |
| Lot Coverage Exempt | - | ADUs up to 800 sq ft |
| Height (at property line) | - | 16 ft max, else 4 ft setback |
Highlighted rows indicate differences between cities.
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.
Fallbrook FAQ
Can I build an ADU in unincorporated San Diego County?
Yes. State law requires the County to allow ADUs on residential properties. Detached ADUs up to 1,200 sq ft are permitted with a building permit from County PDS.
What are the setback requirements for an ADU?
Both attached and detached ADUs must maintain at least 4-foot side and rear setbacks. Detached ADUs 16 feet tall or less may be at the property line. Front setbacks follow the underlying zone.
Does an ADU count toward lot coverage?
ADUs up to 800 sq ft are exempt from lot coverage requirements, meaning you can build one even if your lot is at the maximum allowed coverage.
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