San Anselmo, Marin County

Room Addition Cost in San Anselmo, CA

San Anselmo remodeling costs are 20% abovethe California state average. Here's what a typical room addition costs in San Anselmo in 2026, based on a 300 sqf project.

Budget

$72,000

$240/sqf

Mid-Range

$126,000

$420/sqf

High-End

$198,000

$660/sqf

Cost breakdown

Foundation & Framing

30%$37,800

Roofing & Exterior

15%$18,900

Mechanical (HVAC, Electrical)

15%$18,900

Interior Finishes

20%$25,200

Windows & Doors

10%$12,600

Permits & Engineering

10%$12,600

Breakdown based on mid-range estimate of $126,000

Typical Timeline

3-6 months

Permits Required

Building permit, structural engineering, possibly zoning approval.

Remodeling in San Anselmo

Ross Valley community with Craftsman and cottage-style homes. The downtown core has an artsy character. Flood zone properties near San Anselmo Creek require specific considerations.

A room addition adds square footage and value to your home. Costs depend on whether it's a simple bump-out, a second story, or a full wing addition with plumbing.

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