SB 1211 for 10-unit apartment in Walnut Creek
A 10-unit 10-unit apartment in Walnut Creek qualifies for up to 10 new homes under SB 1211 — 8 detached ADUs and 2 interior conversions. At Walnut Creek's median rent of $2,700/mo, that's ~$324K in additional gross annual rent.
The Walnut Creek scenario
The scenario most Walnut Creek 10-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.
Walnut Creek watch: Tree preservation ordinance can affect placement.
Large multifamily (10+ unit) design playbook
A 10-unit complex is capped at 8 detached ADUs by statute, so the play shifts toward interior conversions: max(1, ⌊units × 25%⌋) = 2 additional units carved from common rooms, oversized lobbies, basement storage, or laundry rooms.
Pro-forma snapshot
| Existing units | 10 |
| Detached ADUs (SB 1211) | 8 |
| Interior conversions | 2 |
| Total new units | 10 |
| Median 1BR rent in Walnut Creek | $2,700/mo |
| Est. additional gross rent | $324K/yr |
| Estimated total project cost | ~$2,016K |
| Year-1 NOI estimate | ~$243K |
| Stabilized cap rate at cost | 12.1% |
| Replacement parking required | No (§66313) |
| Approval pathway | Ministerial · §66314 |
| Typical permit timeline in Walnut Creek | 75-120 days |
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