SB 1211 for 10-unit apartment Buildings
Here's how SB 1211 reads on a 10-unit lot: A 10-unit apartment. SB 1211 caps detached ADUs at 8 — the rest must be interior conversions.
The math, explained
SB 1211 caps detached ADUs at the lesser of 8 or your existing unit count. A 10-unit 10-unit apartment lot therefore qualifies for 8 detached ADUs. The interior-conversion rule (max(1, ⌊units × 25%⌋)) adds 2 more, for a total of 10.
Design playbook for large multifamily (10+ unit)
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.
Cost expectations
Interior-conversion cost runs $150–$280/sf — meaningfully cheaper than ground-up. Combined with 8 detached ADUs, large-complex projects often see the strongest blended IRR.
What to watch out for
Construction phasing matters: keeping 10 existing tenants in place during a 2-unit interior conversion plus 8 ground-up detached ADUs requires real coordination.
Get a personalized SB 1211 feasibility report for 10-unit apartment owners
3 minutes. We email you a 4-page PDF with your buildable count, parking determination, jurisdiction overlays, and pro-forma.
No spam · free · delivered in 24 hrs