Martinez, Contra Costa County

ADU / Guest House Cost in Martinez, CA

Martinez remodeling costs are nearthe California state average. Here's what a typical adu / guest house costs in Martinez 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 Martinez

County seat with a mix of Victorian and mid-century homes. More affordable than southern Contra Costa. Waterfront area has specific building requirements.

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.

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Other projects in Martinez

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

Corte Madera
$150,000 – $360,000 | Marin County
Fairfax
$143,750 – $345,000 | Marin County
Temecula
$112,500 – $270,000 | Riverside County
Santa Monica
$150,000 – $360,000 | Los Angeles County
Napa
$143,750 – $345,000 | Napa County
Newport Beach
$156,250 – $375,000 | Orange County
Anaheim
$131,250 – $315,000 | Orange County
Pasadena
$137,500 – $330,000 | Los Angeles County

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