Modesto, Stanislaus County

Room Addition Cost in Modesto, CA

Modesto remodeling costs are 20% belowthe California state average. Here's what a typical room addition costs in Modesto in 2026, based on a 300 sqf project.

Budget
$48,000
$160/sqf
Mid-Range
$84,000
$280/sqf
High-End
$132,000
$440/sqf

Cost breakdown

Foundation & Framing
30%$25,200
Roofing & Exterior
15%$12,600
Mechanical (HVAC, Electrical)
15%$12,600
Interior Finishes
20%$16,800
Windows & Doors
10%$8,400
Permits & Engineering
10%$8,400

Breakdown based on mid-range estimate of $84,000

Typical Timeline
3-6 months
Permits Required

Building permit, structural engineering, possibly zoning approval.

Remodeling in Modesto

Northern Central Valley city with very affordable remodeling. Many 1960s-70s homes due for updates. Hot summers make insulation and HVAC top priorities.

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.

Have estimates for your Modesto project?

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

Compare Estimates →

Other projects in Modesto

Kitchen Remodel
$24,000 – $72,000
Bathroom Remodel
$12,000 – $38,400
ADU / Guest House
$100,000 – $240,000
Roof Replacement
$10,000 – $30,000
Exterior Paint
$4,000 – $14,000
Whole House Remodel
$216,000 – $720,000

Room Addition cost in other California cities

Antioch
$57,000 – $156,750 | Contra Costa County
Newark
$66,000 – $181,500 | Alameda County
Concord
$60,000 – $165,000 | Contra Costa County
Santa Monica
$72,000 – $198,000 | Los Angeles County
El Monte
$54,000 – $148,500 | Los Angeles County
Ross
$84,000 – $231,000 | Marin County
Dublin
$66,000 – $181,500 | Alameda County
Chula Vista
$57,000 – $156,750 | San Diego 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 →