Half Moon Bay, San Mateo County

ADU / Guest House Cost in Half Moon Bay, CA

Half Moon Bay remodeling costs are 20% abovethe California state average. Here's what a typical adu / guest house costs in Half Moon Bay in 2026, based on a 500 sqf project.

Budget
$150,000
$300/sqf
Mid-Range
$240,000
$480/sqf
High-End
$360,000
$720/sqf

Cost breakdown

Foundation & Framing
25%$60,000
Mechanical (HVAC, Plumbing, Electrical)
20%$48,000
Interior Finishes
20%$48,000
Exterior & Roofing
15%$36,000
Kitchen & Bath Fixtures
10%$24,000
Permits, Plans & Engineering
10%$24,000

Breakdown based on mid-range estimate of $240,000

Typical Timeline
4-8 months
Permits Required

Building, electrical, plumbing, mechanical. May require plan check.

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.

California allows ADUs on most residential lots since 2020. An ADU adds living space and rental income. Cities must approve or deny within 60 days of a complete application.

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Other projects in Half Moon Bay

Kitchen Remodel
$36,000 – $108,000
Bathroom Remodel
$18,000 – $57,600
Room Addition
$72,000 – $198,000
Roof Replacement
$15,000 – $45,000
Exterior Paint
$6,000 – $21,000
Whole House Remodel
$324,000 – $1,080,000

ADU / Guest House cost in other California cities

Visalia
$93,750 – $225,000 | Tulare County
Santa Monica
$150,000 – $360,000 | Los Angeles County
Los Angeles
$131,250 – $315,000 | Los Angeles County
San Clemente
$137,500 – $330,000 | Orange County
Anaheim
$131,250 – $315,000 | Orange County
Whittier
$118,750 – $285,000 | Los Angeles County
Torrance
$125,000 – $300,000 | Los Angeles County
Redondo Beach
$137,500 – $330,000 | Los Angeles County

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