Atherton, San Mateo County

ADU / Guest House Cost in Atherton, CA

Atherton remodeling costs are 40% abovethe California state average. Here's what a typical adu / guest house costs in Atherton in 2026, based on a 500 sqf project.

Budget
$175,000
$350/sqf
Mid-Range
$280,000
$560/sqf
High-End
$420,000
$840/sqf

Cost breakdown

Foundation & Framing
25%$70,000
Mechanical (HVAC, Plumbing, Electrical)
20%$56,000
Interior Finishes
20%$56,000
Exterior & Roofing
15%$42,000
Kitchen & Bath Fixtures
10%$28,000
Permits, Plans & Engineering
10%$28,000

Breakdown based on mid-range estimate of $280,000

Typical Timeline
4-8 months
Permits Required

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

Remodeling in Atherton

One of the wealthiest zip codes in America. Remodeling projects here routinely exceed $500K. Expect premium contractor rates, architectural review, and extended permit timelines. Many projects involve estate-scale renovations.

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 Atherton

Kitchen Remodel
$42,000 – $126,000
Bathroom Remodel
$21,000 – $67,200
Room Addition
$84,000 – $231,000
Roof Replacement
$17,500 – $52,500
Exterior Paint
$7,000 – $24,500
Whole House Remodel
$378,000 – $1,260,000

ADU / Guest House cost in other California cities

Mission Viejo
$131,250 – $315,000 | Orange County
Tiburon
$168,750 – $405,000 | Marin County
Foster City
$156,250 – $375,000 | San Mateo County
Brentwood
$125,000 – $300,000 | Contra Costa County
Burlingame
$162,500 – $390,000 | San Mateo County
San Mateo
$156,250 – $375,000 | San Mateo County
Vallejo
$118,750 – $285,000 | Solano County
San Leandro
$137,500 – $330,000 | Alameda County

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