SB 1211 for 5-unit apartment in Costa Mesa
Own a 5-unit apartment in Costa Mesa? SB 1211 lets you stack 6 new units on top of your existing 5: 5 detached + 1 interior. At Costa Mesa's median rent of $2,700/mo, that's ~$194K in additional gross annual rent.
The Costa Mesa scenario
Picture the typical case: a 5-unit 5-unit apartment on a Costa Mesa block built between 1955 and 1975, with surface parking that hasn't been fully utilized in years. SB 1211 turns that parking into 5 detached units plus 1 interior conversion — 6 new doors that didn't exist before 2024.
Costa Mesa watch: OC infill market.
Mid-size multifamily (5–8 unit) design playbook
This is SB 1211's sweet spot. A 5-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 | 5 |
| Detached ADUs (SB 1211) | 5 |
| Interior conversions | 1 |
| Total new units | 6 |
| Median 1BR rent in Costa Mesa | $2,700/mo |
| Est. additional gross rent | $194K/yr |
| Estimated total project cost | ~$1,478K |
| Year-1 NOI estimate | ~$146K |
| Stabilized cap rate at cost | 9.9% |
| Replacement parking required | No (§66313) |
| Approval pathway | Ministerial · §66314 |
| Typical permit timeline in Costa Mesa | 75-120 days |
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