Cost guide · San Francisco · San Francisco DBI (Department of Building Inspection)
San Francisco ADU cost guide — every line, no surprises
A fixed-price San Francisco ADU contract is the sum of five line items: base build, San Francisco DBI (Department of Building Inspection) permits and fees, design and engineering, sitework and utilities, and finishes. Below is how each one moves in San Francisco specifically — and where homeowners get burned by quotes that hide them.
City-specific deep dives
- Cost guideSan Francisco line-item budget guideEvery line item, 2026 prices, no surprises. The number you should be quoting from.
- Permits guideSan Francisco permits: fees & review windowsPlan-check workflow, fees, and realistic turnaround for this jurisdiction.
- Timeline guideSan Francisco project timeline — phase by phasePhase-by-phase schedule grounded in active builds, not optimistic Gantt charts.
Base build — what $/sqft actually covers
Base build in San Francisco runs $385–$520 per square foot for a detached one-bedroom ADU at 2026 pricing. That number assumes Title 24 compliance, code-minimum insulation, mid-grade finishes, and standard MEP. Anything below $360/sqft in San Francisco is either skipping permits, skipping engineering, or carrying allowance line-items that will balloon during construction.
San Francisco DBI (Department of Building Inspection) fees & soft costs
San Francisco plan-check, school fees, sewer capacity, water meter, and utility connection fees typically land between $14,000 and $28,000. The variance is driven by lot conditions: a flat San Francisco lot on existing sewer is the low end; a hillside lot needing a new lateral and water tap is the high end. We pull these numbers at feasibility, not after deposit.
Design, engineering, and soils
Architectural design, structural engineering, Title 24 compliance, and (when San Francisco requires it) a geotechnical report typically run 8–11% of project cost. Hillside-zoned parcels and properties within special review overlays push this higher. We disclose the engineering scope up front so the design fee isn't a moving target.
Sitework, utilities, and the hidden 15%
Sitework in San Francisco — demolition, grading, retaining if needed, sewer tie-in, water service upgrade, electrical panel upgrade to 200A — is where most "cheap" quotes blow up. Older San Francisco homes nearly always need a panel upgrade and often a lateral upgrade. Budget 12–18% of project cost here. We scope this at survey, before contract.
Finishes — the only line you actually control
Finish allowances (cabinets, counters, flooring, fixtures, appliances) are the single line a San Francisco homeowner can move materially up or down. Going from builder-grade to mid-luxe adds roughly $35–$60 per square foot. Going to luxury finishes can add $90+/sqft. We model three finish tiers at design so the trade-off is visible, not buried.
San Francisco · Cost guide
Questions San Francisco homeowners ask about cost
Direct answers, San Francisco-specific.
Can I build a detached ADU in San Francisco?
Rarely — SF's small lots and rear-yard rules usually push ADU work toward ground-floor conversion of garage or storage space. We confirm options at feasibility.What's the SF soft-story retrofit list?
A city list of multi-unit wood-frame buildings with a soft ground floor that must be retrofitted for seismic. If your building is on it, retrofit must be addressed alongside any ADU work.Does San Francisco have unique requirements that affect cost?
Yes — San Francisco DBI (Department of Building Inspection) sets the local rules, and San Francisco has its own plan-check rhythm. The realistic numbers above reflect 2026 San Francisco conditions, not statewide averages.
Continue researching San Francisco
- San Francisco adu — true all-in costCost transparency
- San Francisco ADU rental yield modelFinancial modeling
- Financing options for California ADUsCapital options
- San Francisco adu — every cost question, answeredFAQ — Cost & Budget
- ADU permits in San Francisco: every questionFAQ — Permits & Code
- How long does it really take in San Francisco?FAQ — Timeline & Phases
- How San Francisco owners pay for itFAQ — Financing & ROI
- Design FAQ — materials, layouts, energy codeFAQ — Design & Specs
- San Francisco rental income reality checkFAQ — Rental & Tax
- Pricing in neighboring Beverly HillsCross-city signal
- Compare adu in San Francisco vs Santa MonicaCross-city signal
- Pasadena adu — permits & turnaroundCross-city signal
- Compare adu in San Francisco vs Long BeachCross-city signal
- Burbank adu — permits & turnaroundCross-city signal
- San Francisco owners often also consider GlendaleCross-city signal
- Browse every city we build ADUs inService hub
- San Francisco ADU permitting: the 2026 rulebookEditorial deep-dive
- Deep dive — San Francisco detached ADU cost in 2026: the honest 600 sq ft numberEditorial deep-dive
- Detached, attached, or conversion: choosing the right ADU typeEditorial deep-dive
- San Francisco build profile — Culver ConversionProof of work
- See our Manhattan Beach Studio in San FranciscoProof of work
- Pillar guide: LegalPillar guide
- TimelinePillar guide
- Definition: ADUEntity definition
- Definition: JADUEntity definition
- Detached ADU — glossary entryEntity definition
- Definition: Attached ADUEntity definition
- California permit directory — San Francisco jurisdictionAuthority signal