Antioch, Contra Costa County

Room Addition Cost in Antioch, CA

Antioch remodeling costs are nearthe California state average. Here's what a typical room addition costs in Antioch in 2026, based on a 300 sqf project.

Budget
$57,000
$190/sqf
Mid-Range
$99,750
$333/sqf
High-End
$156,750
$523/sqf

Cost breakdown

Foundation & Framing
30%$29,925
Roofing & Exterior
15%$14,963
Mechanical (HVAC, Electrical)
15%$14,963
Interior Finishes
20%$19,950
Windows & Doors
10%$9,975
Permits & Engineering
10%$9,975

Breakdown based on mid-range estimate of $99,750

Typical Timeline
3-6 months
Permits Required

Building permit, structural engineering, possibly zoning approval.

Remodeling in Antioch

Most affordable Bay Area city for remodeling. East County location with newer housing stock. Hot Delta climate makes energy efficiency and HVAC critical project components.

A room addition adds square footage and value to your home. Costs depend on whether it's a simple bump-out, a second story, or a full wing addition with plumbing.

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Other projects in Antioch

Kitchen Remodel
$28,500 – $85,500
Bathroom Remodel
$14,250 – $45,600
ADU / Guest House
$118,750 – $285,000
Roof Replacement
$11,875 – $35,625
Exterior Paint
$4,750 – $16,625
Whole House Remodel
$256,500 – $855,000

Room Addition cost in other California cities

Hayward
$63,000 – $173,250 | Alameda County
Benicia
$60,000 – $165,000 | Solano County
Visalia
$45,000 – $123,750 | Tulare County
Corona
$54,000 – $148,500 | Riverside County
Millbrae
$72,000 – $198,000 | San Mateo County
Pleasanton
$69,000 – $189,750 | Alameda County
Rancho Cucamonga
$54,000 – $148,500 | San Bernardino County
Oxnard
$57,000 – $156,750 | Ventura County

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