Fullerton, Orange County

ADU / Guest House Cost in Fullerton, CA

Fullerton remodeling costs are nearthe California state average. Here's what a typical adu / guest house costs in Fullerton in 2026, based on a 500 sqf project.

Budget
$125,000
$250/sqf
Mid-Range
$200,000
$400/sqf
High-End
$300,000
$600/sqf

Cost breakdown

Foundation & Framing
25%$50,000
Mechanical (HVAC, Plumbing, Electrical)
20%$40,000
Interior Finishes
20%$40,000
Exterior & Roofing
15%$30,000
Kitchen & Bath Fixtures
10%$20,000
Permits, Plans & Engineering
10%$20,000

Breakdown based on mid-range estimate of $200,000

Typical Timeline
4-8 months
Permits Required

Building, electrical, plumbing, mechanical. May require plan check.

Remodeling in Fullerton

North OC city with charming downtown and historic homes. College town energy drives demand for rental property improvements. More affordable than south OC.

California allows ADUs on most residential lots since 2020. An ADU adds living space and rental income. Cities must approve or deny within 60 days of a complete application.

Have estimates for your Fullerton project?

Upload them and get an AI-powered comparison with CSLB license verification. Free.

Compare Estimates →

Other projects in Fullerton

Kitchen Remodel
$30,000 – $90,000
Bathroom Remodel
$15,000 – $48,000
Room Addition
$60,000 – $165,000
Roof Replacement
$12,500 – $37,500
Exterior Paint
$5,000 – $17,500
Whole House Remodel
$270,000 – $900,000

ADU / Guest House cost in other California cities

Santa Monica
$150,000 – $360,000 | Los Angeles County
Santa Cruz
$143,750 – $345,000 | Santa Cruz County
Beverly Hills
$162,500 – $390,000 | Los Angeles County
Encinitas
$137,500 – $330,000 | San Diego County
Pomona
$112,500 – $270,000 | Los Angeles County
Calabasas
$143,750 – $345,000 | Los Angeles County
Castro Valley
$137,500 – $330,000 | Alameda County
Temecula
$112,500 – $270,000 | Riverside County

Get a personalized estimate

Use our interactive cost estimator to adjust square footage and see detailed pricing for your specific project.

Open Cost Estimator →