// Fullerton

ADU Construction in Fullerton

Cal State Fullerton's 40,000+ students drive enormous and consistent rental demand. Diverse lot sizes from hillside estates to flatland residential parcels offer flexibility, and a strong young professional population supports premium rents near downtown.

Fullerton is a vibrant north Orange County city of approximately 140,000 residents, defined by its relationship with Cal State Fullerton — one of the largest universities in the CSU system with over 40,000 students. The city features diverse neighborhoods ranging from the walkable downtown core with its restaurants, bars, and live music venues, to the upscale hillside homes of Sunny Hills and Raymond Hills, to established flatland neighborhoods near the university. Fullerton's Metrolink and Amtrak station connects to Los Angeles and San Diego, and the city enforces a 31-day minimum rental period on ADUs, effectively prohibiting short-term vacation rentals while supporting the long-term housing market.

Zoning & requirements

Setbacks
4-foot minimum from rear and side property lines for new detached ADUs. Conversions of existing structures are exempt from setback requirements.
Height
Up to 16 feet for detached ADUs. Up to 25 feet for attached ADUs in qualifying residential zones.
Parking
One parking space per ADU may be required. Exempt if within 0.5 miles of public transit (including Fullerton Transportation Center), if the property is in a designated Preservation "P" zone, or if the property is on the local historic register.
Lot Size
6,000–9,000 sqft for standard residential neighborhoods. Hillside properties in Sunny Hills and Raymond Hills may be significantly larger. No minimum lot size required by state law to build an ADU.
Owner Occupancy
No owner-occupancy requirement for ADUs (made permanent by AB 976 in 2025).
Additional Notes
Fullerton enforces a 31-day minimum rental period for ADUs — short-term rentals (Airbnb, VRBO) are not permitted. Properties in Preservation "P" zones or on the local historic register receive automatic parking exemptions. The city's Fullerton Transportation Center (Metrolink/Amtrak) creates a large transit-proximity exemption zone.

How to permit your ADU in Fullerton

01

Verify zoning & lot characteristics

Check your property on the City of Fullerton zoning map. Determine whether your parcel is in a Preservation "P" zone or on the local historic register, as this affects parking requirements. Hillside properties may have additional grading and geotechnical requirements.

02

Design your ADU

Create architectural plans including site plan, floor plan, elevations, structural, mechanical, electrical, and plumbing. Consider the target rental market — student housing near CSUF vs. young professional housing near downtown vs. family housing in Sunny Hills.

03

Submit to Community & Economic Development

Submit your complete plan set to the Planning & Zoning Division at 303 W. Commonwealth Avenue. Include structural engineering, Title 24 energy calculations, and a soils/geotechnical report if on a hillside lot.

04

Plan check review

The city reviews plans for compliance with building codes and ADU regulations. State law mandates a 60-day maximum review period for compliant ADU applications.

05

Build & inspect

Once permitted, begin construction with your licensed contractor. Schedule required inspections at each milestone — foundation, framing, rough MEP, insulation, and final.

06

Final inspection & occupancy

Request final inspection from the Building Division. Once passed, receive your Certificate of Occupancy. Remember: 31-day minimum rental period applies — no short-term rentals.

City of Fullerton Community & Economic Development Department — Planning & Zoning Division, 303 W. Commonwealth Avenue • Fees: $5,000–$12,000 total (plan check, building permit, school fees). Impact fees waived for ADUs under 750 sqft. • Timeline: 4–8 weeks for plan check. 60-day maximum review required by state law.

Get your Fullerton ADU estimate