ADU Regulations in El Cajon, California
San Diego County · CA · Pop. 105,000
Max ADU Size
1,200
sq ft detached
Rear Setback
4 ft
Permit Timeline
60 days
Build Cost
$150,000 – $305,000
Zoning
Allowed ADU Types
State law preempts local owner-occupancy requirements. East San Diego County lots tend to be larger than coastal San Diego, offering more flexibility for detached ADU placement. One ADU plus one JADU permitted per single-family lot.
Source: City of El Cajon — Accessory Dwelling Units · El Cajon Municipal Code Title 17 (Zoning Ordinance)
Dimensions
Size & Setback Requirements
Detached
1,200
sq ft max
JADU
500
sq ft max
Attached
50% of primary home, max 1,200 sq ft
Setbacks
front
Same as primary dwelling
side
4 ft
rear
4 ft
Max height: 16 ft
Lot coverage: Per underlying zone
El Cajon's larger lot sizes in suburban neighborhoods often allow for full 1,200 sq ft detached ADUs. Garage conversions retain existing setbacks. Hillside lots may require additional grading review.
Permitting
Permit Process
Department
City of El Cajon Development Services Department — Planning Division
Review Timeline
60 days
Permit Fees
$6,500 – $13,000
Impact Fees
Impact fees waived for ADUs under 750 sq ft per state law
Required Documents
- ›Site plan
- ›Floor plans
- ›Elevations
- ›Title 24 energy compliance
- ›Structural drawings
- ›Grading plan (if applicable for hillside lots)
El Cajon follows state-mandated ministerial ADU approval. The Development Services counter accepts both in-person and digital submittals. Garage conversions are processed quickly due to existing structure footprint. Check for any Helix Water District connection fee requirements.
Visit City of El Cajon Development Services Department — Planning Division →Infrastructure
Utilities & Requirements
Solar
Required
Parking
Not required
Separate Meter
Optional
Fire Sprinklers
See note
Financials
ADU Costs in El Cajon
Typical Build Cost
$150,000 – $305,000
Cost per Sq Ft
$210 – $275
Monthly Rental
$1,500 – $2,400/mo/mo
Property Value Added
Adds $175,000 – $320,000 to property value
Available Grants & Programs
- ★CalHFA ADU Grant Program available
- ★San Diego County ADU financing programs
El Cajon offers strong ADU ROI in the broader San Diego region at lower construction costs than coastal neighborhoods. Large lots are common in established residential neighborhoods, making detached ADUs feasible on many parcels. Working-family rental market is robust with steady demand from East County residents.
Use the free ADU Cost Calculator →Free Service
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El Cajon Quick Facts
- Max size1,200 sq ft
- Rear setback4 ft
- Permit timeline60 days
- Build cost$150,000 – $305,000
- Rental income$1,500 – $2,400/mo/mo
- Owner occupancyNot required
Official Source
City of El Cajon — Accessory Dwelling UnitsEl Cajon Municipal Code Title 17 (Zoning Ordinance)
Last verified: March 14, 2026
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