How much does an ADU cost in San Francisco?

A garage conversion ADU typically costs $180,000–$350,000. A new-construction detached ADU runs $350,000–$550,000+. A basement ADU conversion typically costs $200,000–$400,000 depending on ceiling height and existing conditions.

Does an ADU add value to my San Francisco property?

Yes — a legal ADU typically adds $200,000–$500,000+ in property value in San Francisco, on top of any rental income it generates, making it one of the highest-ROI renovation projects in the city.

Do I need a variance or special approval to build an ADU in San Francisco?

No. Under current California ADU law, most single-family and multi-family properties can build one ADU and one Junior ADU by right, with no discretionary hearing required — though the project still needs to meet building and fire code and go through standard DBI permitting.

SOLID BAY

CONSTRUCTION · SAN FRANCISCO · EST. 2016

(415) 888-5361

Cost Guide · San Francisco

ADU Cost in San Francisco: Complete 2026 Pricing Breakdown

By Solid Bay Construction SF | Updated 2026

ADU cost in San Francisco varies more by type than almost any other renovation project — a garage conversion, a basement unit, and new detached construction start from very different baselines. Here's what each actually costs.

ADU Cost by Type

ADU Type	Typical Cost
Garage conversion ADU	$180,000–$350,000
Basement conversion ADU	$200,000–$400,000
New detached (backyard) ADU	$350,000–$550,000+
Junior ADU (JADU, up to 500 sq ft, within existing structure)	$80,000–$180,000

Why Garage Conversions Are the Most Cost-Effective ADU

A garage conversion starts with an existing foundation, roof, and structure already in place — you're building out interior systems and finishes rather than starting from bare dirt. That's why it remains the lowest-cost path to a legal ADU for most SF homeowners, and why it's consistently our most-requested ADU project type.

What Drives ADU Cost Within Each Type

Foundation condition — an older garage often needs foundation work before conversion, which adds $15,000–$80,000+ depending on scope
Utility distance — how far the ADU sits from existing sewer, water, and electrical service points affects trenching and connection cost
Kitchen vs. kitchenette — a full kitchen (required for a standard ADU, not a JADU) adds plumbing, electrical, and ventilation cost over a JADU's kitchenette
Finish level — rental-grade finishes vs. a unit built to match the main house's finish level can swing the budget by $50,000–$100,000+

ADU Return on Investment

A legal ADU typically adds $200,000–$500,000+ in property value in San Francisco — on top of whatever rental income it generates while you own the home. Combined with SF's by-right ADU approval process (no discretionary hearing required for most properties), it's consistently one of the highest-ROI projects we build.

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