Costa Mesa, Orange County

Room Addition Cost in Costa Mesa, CA

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

Budget
$63,000
$210/sqf
Mid-Range
$110,250
$368/sqf
High-End
$173,250
$578/sqf

Cost breakdown

Foundation & Framing
30%$33,075
Roofing & Exterior
15%$16,538
Mechanical (HVAC, Electrical)
15%$16,538
Interior Finishes
20%$22,050
Windows & Doors
10%$11,025
Permits & Engineering
10%$11,025

Breakdown based on mid-range estimate of $110,250

Typical Timeline
3-6 months
Permits Required

Building permit, structural engineering, possibly zoning approval.

Remodeling in Costa Mesa

Central OC location with mix of affordable and premium neighborhoods. Eastside Costa Mesa has strong renovation potential. South Coast Metro area attracts higher-end projects.

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 Costa Mesa

Kitchen Remodel
$31,500 – $94,500
Bathroom Remodel
$15,750 – $50,400
ADU / Guest House
$131,250 – $315,000
Roof Replacement
$13,125 – $39,375
Exterior Paint
$5,250 – $18,375
Whole House Remodel
$283,500 – $945,000

Room Addition cost in other California cities

Sausalito
$78,000 – $214,500 | Marin County
San Bruno
$72,000 – $198,000 | San Mateo County
Milpitas
$69,000 – $189,750 | Santa Clara County
Castro Valley
$66,000 – $181,500 | Alameda County
Fairfax
$69,000 – $189,750 | Marin County
Livermore
$63,000 – $173,250 | Alameda County
Vacaville
$54,000 – $148,500 | Solano County
La Jolla
$72,000 – $198,000 | San Diego County

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