Lafayette, Contra Costa County

ADU / Guest House Cost in Lafayette, CA

Lafayette remodeling costs are 20% abovethe California state average. Here's what a typical adu / guest house costs in Lafayette 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 Lafayette

Affluent Lamorinda community with established homes on larger lots. Premium finishes are the norm. Hillside lots may require additional engineering for additions.

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 Lafayette

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

Dublin
$137,500 – $330,000 | Alameda County
Elk Grove
$112,500 – $270,000 | Sacramento County
Fullerton
$125,000 – $300,000 | Orange County
Union City
$137,500 – $330,000 | Alameda County
Glendale
$131,250 – $315,000 | Los Angeles County
Santa Monica
$150,000 – $360,000 | Los Angeles County
Mill Valley
$162,500 – $390,000 | Marin County
Calabasas
$143,750 – $345,000 | Los Angeles County

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