Half Moon Bay, San Mateo County

Room Addition Cost in Half Moon Bay, CA

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

Budget
$72,000
$240/sqf
Mid-Range
$126,000
$420/sqf
High-End
$198,000
$660/sqf

Cost breakdown

Foundation & Framing
30%$37,800
Roofing & Exterior
15%$18,900
Mechanical (HVAC, Electrical)
15%$18,900
Interior Finishes
20%$25,200
Windows & Doors
10%$12,600
Permits & Engineering
10%$12,600

Breakdown based on mid-range estimate of $126,000

Typical Timeline
3-6 months
Permits Required

Building permit, structural engineering, possibly zoning approval.

Remodeling in Half Moon Bay

Coastal community with limited contractor supply due to its location west of the hills. Marine environment requires corrosion-resistant materials. Permit process is straightforward but contractor travel adds cost.

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 Half Moon Bay

Kitchen Remodel
$36,000 – $108,000
Bathroom Remodel
$18,000 – $57,600
ADU / Guest House
$150,000 – $360,000
Roof Replacement
$15,000 – $45,000
Exterior Paint
$6,000 – $21,000
Whole House Remodel
$324,000 – $1,080,000

Room Addition cost in other California cities

Pasadena
$66,000 – $181,500 | Los Angeles County
Culver City
$66,000 – $181,500 | Los Angeles County
Sacramento
$54,000 – $148,500 | Sacramento County
Oxnard
$57,000 – $156,750 | Ventura County
El Monte
$54,000 – $148,500 | Los Angeles County
Calabasas
$69,000 – $189,750 | Los Angeles County
La Jolla
$72,000 – $198,000 | San Diego County
Sherman Oaks
$63,000 – $173,250 | Los Angeles County

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