Belmont, San Mateo County

ADU / Guest House Cost in Belmont, CA

Belmont remodeling costs are 25% abovethe California state average. Here's what a typical adu / guest house costs in Belmont in 2026, based on a 500 sqf project.

Budget
$156,250
$313/sqf
Mid-Range
$250,000
$500/sqf
High-End
$375,000
$750/sqf

Cost breakdown

Foundation & Framing
25%$62,500
Mechanical (HVAC, Plumbing, Electrical)
20%$50,000
Interior Finishes
20%$50,000
Exterior & Roofing
15%$37,500
Kitchen & Bath Fixtures
10%$25,000
Permits, Plans & Engineering
10%$25,000

Breakdown based on mid-range estimate of $250,000

Typical Timeline
4-8 months
Permits Required

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

Remodeling in Belmont

Hillside community with many split-level and multi-story homes. Terrain can complicate additions and structural work. Views drive premium pricing for homes with potential.

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 Belmont

Kitchen Remodel
$37,500 – $112,500
Bathroom Remodel
$18,750 – $60,000
Room Addition
$75,000 – $206,250
Roof Replacement
$15,625 – $46,875
Exterior Paint
$6,250 – $21,875
Whole House Remodel
$337,500 – $1,125,000

ADU / Guest House cost in other California cities

Sherman Oaks
$131,250 – $315,000 | Los Angeles County
Calabasas
$143,750 – $345,000 | Los Angeles County
Oceanside
$125,000 – $300,000 | San Diego County
Lafayette
$150,000 – $360,000 | Contra Costa County
Bakersfield
$100,000 – $240,000 | Kern County
Union City
$137,500 – $330,000 | Alameda County
Dublin
$137,500 – $330,000 | Alameda County
Sausalito
$162,500 – $390,000 | Marin County

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