SB 1211 for 8-unit apartment in San Mateo
A 8-unit 8-unit apartment in San Mateo qualifies for up to 10 new homes under SB 1211 — 8 detached ADUs and 2 interior conversions. At San Mateo's median rent of $3,000/mo, that's ~$360K in additional gross annual rent.
The San Mateo scenario
The scenario most San Mateo 8-unit apartment owners face: an existing building, mature trees, and a back lot that's currently doing nothing. SB 1211's 4-ft setback and 18-ft height envelope fits 8 detached units behind that primary structure with room for fire-access in front.
San Mateo-specific note: Peninsula tech rents; very strong upside.
Mid-size multifamily (5–8 unit) design playbook
This is SB 1211's sweet spot. A 8-unit existing building maxes out the 8-detached cap (or comes close), so design moves are about packing detached ADUs efficiently around the existing structure and converting underutilized parking.
Pro-forma snapshot
| Existing units | 8 |
| Detached ADUs (SB 1211) | 8 |
| Interior conversions | 2 |
| Total new units | 10 |
| Median 1BR rent in San Mateo | $3,000/mo |
| Est. additional gross rent | $360K/yr |
| Estimated total project cost | ~$2,464K |
| Year-1 NOI estimate | ~$270K |
| Stabilized cap rate at cost | 11.0% |
| Replacement parking required | No (§66313) |
| Approval pathway | Ministerial · §66314 |
| Typical permit timeline in San Mateo | 75-130 days |
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