ADUByCity
Verified March 14, 2026

ADU Regulations in Downey, California

Los Angeles County · CA · Pop. 115,000

Max ADU Size

1,200

sq ft detached

Rear Setback

4 ft

Permit Timeline

60 days

Build Cost

$150,000 – $310,000

Zoning

Allowed ADU Types

✓Detached ADU
✓Attached ADU
✓JADU (Junior ADU)
✓Garage Conversion
Max per lot: 2 ADUs✓ No owner-occupancy required

ADUs and JADUs permitted by right on all residentially zoned lots. Downey is a stable Southeast Los Angeles County bedroom community with consistent working-family rental demand. Owner-occupancy not required per state law.

Source: City of Downey — Accessory Dwelling Units · Downey Municipal Code Article IX (Zoning), Chapter 9312

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 per underlying zone

side

4 ft

rear

4 ft

Max height: 16 ft

Lot coverage: Per underlying zone

Downey's post-war residential neighborhoods feature predominantly single-family homes on standard 6,000–7,000 sq ft lots. Attached garage conversions are a popular ADU approach. Detached ADUs in rear yards are feasible on most standard lots.

Permitting

Permit Process

Department

City of Downey — Planning Division, Community Development Department

Review Timeline

60 days

Permit Fees

$7,000 – $14,000

Impact Fees

Impact fees waived for ADUs under 750 sq ft; prorated for larger units

Required Documents

  • ›Site plan with property dimensions and setbacks
  • ›Floor plans
  • ›Elevations
  • ›Title 24 energy compliance report
  • ›Structural drawings
  • ›Existing floor plan of primary residence (for conversions)

Downey's permit fee range reflects its status as a mid-tier Los Angeles County city. The birthplace of NASA's Apollo space program, Downey attracts aerospace industry workers from nearby facilities. Processing generally meets state 60-day requirements.

Visit City of Downey — Planning Division, Community Development Department →

Infrastructure

Utilities & Requirements

Solar

Required

Parking

Not required

Separate Meter

Optional

Fire Sprinklers

See note

Sewer: Connection to Los Angeles County Sanitation Districts sewer system; separate lateral typically required for detached ADUs
Fire Sprinklers: Not required unless primary structure requires them
Parking: No additional parking required

Financials

ADU Costs in Downey

Typical Build Cost

$150,000 – $310,000

Cost per Sq Ft

$210 – $275

Monthly Rental

$1,500 – $2,400/mo/mo

Property Value Added

Adds $120,000 – $220,000 to property value

Available Grants & Programs

  • ★CalHFA ADU Grant Program available (up to $40,000)
  • ★LA County Community Development Commission programs may be available

Downey's stable Southeast LA location, aerospace industry employment base, and affordable (relative to LA) home prices make it a strong ADU market. The steady working-family rental market supports consistent ADU occupancy.

Use the free ADU Cost Calculator →

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Disclaimer: Information is compiled from publicly available municipal codes for general informational purposes only. It does not constitute legal, zoning, or construction advice. Regulations change frequently. Always verify with your local planning department. Last verified: March 14, 2026. Verify with City of Downey — Planning Division, Community Development Department

Explore More

Nearby Cities in Los Angeles County

Los Angeles

Max 1,200 sq ft · $150,000 – $450,000

Long Beach

Max 1,200 sq ft · $150,000 – $420,000

Santa Clarita

Max 1,200 sq ft · $150,000 – $320,000

Glendale

Max 1,200 sq ft · $160,000 – $370,000

Palmdale

Max 1,200 sq ft · $130,000 – $270,000

Lancaster

Max 1,200 sq ft · $120,000 – $250,000

Downey Quick Facts

  • Max size1,200 sq ft
  • Rear setback4 ft
  • Permit timeline60 days
  • Build cost$150,000 – $310,000
  • Rental income$1,500 – $2,400/mo/mo
  • Owner occupancyNot required

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Official Source

City of Downey — Accessory Dwelling Units

Downey Municipal Code Article IX (Zoning), Chapter 9312

Last verified: March 14, 2026

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