SB 1211 for Triplex in San Francisco
Own a triplex in San Francisco? SB 1211 lets you stack 4 new units on top of your existing 3: 3 detached + 1 interior. At San Francisco's median rent of $3,100/mo, that's ~$149K in additional gross annual rent.
The San Francisco scenario
Picture the typical case: a 3-unit triplex on a San Francisco block built between 1955 and 1975, with surface parking that hasn't been fully utilized in years. SB 1211 turns that parking into 3 detached units plus 1 interior conversion — 4 new doors that didn't exist before 2024.
San Francisco-specific note: SF requires fire sprinklers in most ADU configurations.
Small multifamily (2–4 unit) design playbook
Small multifamily lots are usually constrained on width before they're constrained on count. With a 3-unit existing footprint, the binding constraint becomes side-yard setbacks (4 ft min) and the 18-ft height limit. Two-story stacked-flat ADUs over surface parking are the highest-yield typology.
Pro-forma snapshot
| Existing units | 3 |
| Detached ADUs (SB 1211) | 3 |
| Interior conversions | 1 |
| Total new units | 4 |
| Median 1BR rent in San Francisco | $3,100/mo |
| Est. additional gross rent | $149K/yr |
| Estimated total project cost | ~$1,075K |
| Year-1 NOI estimate | ~$112K |
| Stabilized cap rate at cost | 10.4% |
| Replacement parking required | No (§66313) |
| Approval pathway | Ministerial · §66314 |
| Typical permit timeline in San Francisco | 90-150 days |
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