Gilroy, Santa Clara County

Room Addition Cost in Gilroy, CA

Gilroy remodeling costs are nearthe California state average. Here's what a typical room addition costs in Gilroy 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 Gilroy

Southernmost Silicon Valley city with the most affordable remodeling costs in Santa Clara County. Hot summers make HVAC and insulation priorities. Growing bedroom community.

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 Gilroy

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

Mountain View
$78,000 – $214,500 | Santa Clara County
Redwood City
$75,000 – $206,250 | San Mateo County
Foster City
$75,000 – $206,250 | San Mateo County
Atherton
$84,000 – $231,000 | San Mateo County
San Jose
$75,000 – $206,250 | Santa Clara County
San Carlos
$75,000 – $206,250 | San Mateo County
Los Altos Hills
$84,000 – $231,000 | Santa Clara County
Hayward
$63,000 – $173,250 | Alameda County

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