San Francisco has embraced ADUs as a key housing solution, with one of the most progressive ADU programs in the state. The city offers expedited review, fee waivers, and pre-approved plans to encourage ADU development.
Zoning & Size Requirements [1][2]
| Allowed Zones | RH-1, RH-2, RH-3, RM, RTO zones and most residential districts |
| Max Size (Detached) | 1,200 sq ft (state minimum; local program caps at 850-1,000 sq ft) |
| Max Size (Attached) | 1,000 sq ft or 50% of primary dwelling |
| Max Size (JADU) | 500 sq ft |
| Max Height | 25 ft for detached ADUs |
| Max Units | 1 ADU + 1 JADU per lot |
Setback Requirements [1][2]
| Rear Setback | 4 ft minimum |
| Side Setback | 4 ft minimum |
| Front Setback | Must meet zone's front setback requirement |
| Parking Required | No parking required |
| Owner Occupancy | Not required |
| Min Lot Size | No minimum lot size |
Permit Process & Fees [3]
| Approval Process | Ministerial (no discretionary review or public hearing) |
| Review Timeline | 60-day review period (state-mandated) |
| Permit Fees | $5,000-$20,000 depending on scope |
| Impact Fees | Waived for units under 750 sq ft |
| Plan Check | Expedited plan check available |
| Pre-Approved Plans | Yes — SF has pre-approved ADU plan sets |
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Construction Costs [4][5]
| Average Build Cost | $200,000-$450,000 |
| Cost per Sq Ft | $300-$500 |
| Garage Conversion | $120,000-$250,000 |
| Prefab ADU (Installed) | $150,000-$350,000 |
Finance Your ADU Project
Most ADU projects are funded through HELOCs, construction loans, or cash-out refinancing. Compare rates from top lenders.
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Rental Income Potential [6][7]
| Avg Rent (1 Bedroom) | $2,200-$3,200/mo |
| Avg Rent (2 Bedroom) | $2,800-$4,000/mo |
| Short-Term Rental | Heavily regulated; 90-day annual cap for unhosted |
| Est. Annual ROI | 5-8% annual return |
Explore Prefab ADU Options
Prefab ADUs can save 20-40% vs. traditional construction and cut build time in half.
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Recent Law Changes
What's Changed Recently
- SB 1211 in effect (2025-2026): Up to 8 detached ADUs allowed on multifamily lots statewide
- AB 1033 opt-in expanding (2026): More cities allowing separate sale of ADUs as condos
- Unpermitted ADU amnesty program extended through 2026 for retroactive permits
- New state-funded ADU grant program: Up to $40K for low-income homeowners (2026)
Tips for Building an ADU in San Francisco
- SF's high rents make ADUs particularly profitable despite higher build costs
- Check historic district restrictions before planning your ADU
- Garage conversions are popular in SF due to limited lot space
- Consider a JADU if you want to minimize construction costs
Sources & References
All data on this page is sourced from official government records and verified market data. View our full methodology.
- Design an ADU that meets City codes | SF.gov Planning Department — Accessed 2026-02-24
- Accessory Dwelling Unit (ADU) | SF.gov Planning Department — Accessed 2026-02-24
- Get a building permit for an ADU | SF.gov Planning Department — Accessed 2026-02-24
- HomeAdvisor — ADU Construction Cost Data Market Data — Accessed 2026-02-24
- Angi — Local ADU Contractor Costs Market Data — Accessed 2026-02-24
- Zillow Rental Manager — Market Rent Data Market Data — Accessed 2026-02-24
- HUD Fair Market Rents Government Data — Accessed 2026-02-24
- Prepare for an ADU project | SF.gov Planning Department — Accessed 2026-02-24
- California ADU Handbook — HCD Government Data — Accessed 2026-02-24
Frequently Asked Questions
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