South San Francisco, San Mateo County

ADU / Guest House Cost in South San Francisco, CA

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

Biotech corridor driving home values and renovation demand. Many mid-century homes being modernized. The city has streamlined ADU permitting to address housing demand.

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 South San Francisco

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

Atherton
$175,000 – $420,000 | San Mateo County
San Marcos
$118,750 – $285,000 | San Diego County
Pomona
$112,500 – $270,000 | Los Angeles County
Chula Vista
$118,750 – $285,000 | San Diego County
Beverly Hills
$162,500 – $390,000 | Los Angeles County
Sherman Oaks
$131,250 – $315,000 | Los Angeles County
Millbrae
$150,000 – $360,000 | San Mateo County
Fremont
$143,750 – $345,000 | Alameda County

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