SB 1211 for 12-unit apartment in Costa Mesa
Costa Mesa's SB 1211 math for 12-unit apartment owners: 8 detached ADUs (the §66323 cap), plus 3 interior conversions. Total: 11 new homes. At Costa Mesa's median rent of $2,700/mo, that's ~$356K in additional gross annual rent.
The Costa Mesa scenario
Run it as a sequence: stabilize existing 12 units → permit 8 detached ADUs ministerially under §66314 → convert 3 interior spaces into rentable units → re-tenant at Costa Mesa medians.
Costa Mesa watch: OC infill market.
Large multifamily (10+ unit) design playbook
A 12-unit complex is capped at 8 detached ADUs by statute, so the play shifts toward interior conversions: max(1, ⌊units × 25%⌋) = 3 additional units carved from common rooms, oversized lobbies, basement storage, or laundry rooms.
Pro-forma snapshot
| Existing units | 12 |
| Detached ADUs (SB 1211) | 8 |
| Interior conversions | 3 |
| Total new units | 11 |
| Median 1BR rent in Costa Mesa | $2,700/mo |
| Est. additional gross rent | $356K/yr |
| Estimated total project cost | ~$2,218K |
| Year-1 NOI estimate | ~$267K |
| Stabilized cap rate at cost | 12.0% |
| Replacement parking required | No (§66313) |
| Approval pathway | Ministerial · §66314 |
| Typical permit timeline in Costa Mesa | 75-120 days |
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