Los Altos Hills, Santa Clara County

Room Addition Cost in Los Altos Hills, CA

Los Altos Hills remodeling costs are 40% abovethe California state average. Here's what a typical room addition costs in Los Altos Hills in 2026, based on a 300 sqf project.

Budget
$84,000
$280/sqf
Mid-Range
$147,000
$490/sqf
High-End
$231,000
$770/sqf

Cost breakdown

Foundation & Framing
30%$44,100
Roofing & Exterior
15%$22,050
Mechanical (HVAC, Electrical)
15%$22,050
Interior Finishes
20%$29,400
Windows & Doors
10%$14,700
Permits & Engineering
10%$14,700

Breakdown based on mid-range estimate of $147,000

Typical Timeline
3-6 months
Permits Required

Building permit, structural engineering, possibly zoning approval.

Remodeling in Los Altos Hills

Ultra-premium hillside community with 1+ acre lots. Estate-scale renovations are common. Grading, septic, and hillside construction add significant cost. Limited road access can complicate material delivery.

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 Los Altos Hills

Kitchen Remodel
$42,000 – $126,000
Bathroom Remodel
$21,000 – $67,200
ADU / Guest House
$175,000 – $420,000
Roof Replacement
$17,500 – $52,500
Exterior Paint
$7,000 – $24,500
Whole House Remodel
$378,000 – $1,260,000

Room Addition cost in other California cities

Menlo Park
$81,000 – $222,750 | San Mateo County
Elk Grove
$54,000 – $148,500 | Sacramento County
Mission Viejo
$63,000 – $173,250 | Orange County
Pacifica
$72,000 – $198,000 | San Mateo County
South San Francisco
$72,000 – $198,000 | San Mateo County
Gilroy
$63,000 – $173,250 | Santa Clara County
Hayward
$63,000 – $173,250 | Alameda County
San Mateo
$75,000 – $206,250 | San Mateo County

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