How big can an ADU be in Fremont?

Detached ADUs in Fremont can be up to 1,200 sq ft. Attached ADUs: 50% of primary home, max 1,200 sq ft. JADUs up to 500 sq ft.

How much does it cost to build an ADU in Fremont?

Build costs typically range $200,000 – $420,000, or $280 – $380 per square foot.

Verified March 14, 2026

ADU Regulations in Fremont, California

Q: What are the setback requirements for ADUs in Fremont?

Front: Same as primary dwelling. Side: 4 ft. Rear: 4 ft.

Alameda County · CA · Pop. 240,000

Max ADU Size

1,200

sq ft detached

Rear Setback

4 ft

Permit Timeline

60 days

Build Cost

$200,000 – $420,000

Zoning

Allowed ADU Types

✓Detached ADU

✓Attached ADU

✓JADU (Junior ADU)

✓Garage Conversion

Max per lot: 2 ADUs✓ No owner-occupancy required

ADUs permitted by-right on all residential zoned lots

Source: City of Fremont — Accessory Dwelling Units · Fremont Municipal Code Section 18.25

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

Fremont's large lot sizes in many neighborhoods allow full-size detached ADUs

Permitting

Permit Process

Department

Fremont Planning & Building Department

Review Timeline

60 days

Permit Fees

$10,000 – $20,000

Impact Fees

Impact fees waived under 750 sq ft

Required Documents

›Site plan to scale
›Architectural drawings
›Elevations
›Title 24 energy compliance
›Structural drawings (new construction)

Fremont's pre-approved ADU plan library speeds up the permit process

Visit Fremont Planning & Building Department →

Infrastructure

Utilities & Requirements

Solar

Required

Parking

Not required

Separate Meter

Optional

Fire Sprinklers

See note

Sewer: Connect to ACWD (Alameda County Water District) lateral

Fire Sprinklers: Not required unless primary structure requires them

Parking: No additional parking required

Financials

ADU Costs in Fremont

Typical Build Cost

$200,000 – $420,000

Cost per Sq Ft

$280 – $380

Monthly Rental

$2,200 – $3,500/mo

Property Value Added

Adds $220,000 – $400,000 to property value

Available Grants & Programs

★CalHFA ADU Grant Program available

Bay Area labor costs are high; Fremont's proximity to Silicon Valley drives strong rental demand

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 Fremont Planning & Building Department

Explore More

Nearby Cities in Alameda County

Oakland

Max 1,200 sq ft · $200,000 – $550,000

Hayward

Max 1,200 sq ft · $185,000 – $380,000

Berkeley

Max 1,200 sq ft · $230,000 – $450,000

Livermore

Max 1,200 sq ft · $180,000 – $365,000

San Leandro

Max 1,200 sq ft · $175,000 – $360,000

Fremont Quick Facts

Max size1,200 sq ft
Rear setback4 ft
Permit timeline60 days
Build cost$200,000 – $420,000
Rental income$2,200 – $3,500/mo
Owner occupancyNot required

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Official Source

City of Fremont — Accessory Dwelling Units

Fremont Municipal Code Section 18.25

Last verified: March 14, 2026

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