SB 1211 for Duplex in Fontana
Own a duplex in Fontana? SB 1211 lets you stack 3 new units on top of your existing 2: 2 detached + 1 interior. At Fontana's median rent of $1,900/mo, that's ~$68K in additional gross annual rent.
The Fontana scenario
Picture the typical case: a 2-unit duplex on a Fontana block built between 1955 and 1975, with surface parking that hasn't been fully utilized in years. SB 1211 turns that parking into 2 detached units plus 1 interior conversion — 3 new doors that didn't exist before 2024.
Fontana-specific note: Logistics-driven rent growth.
Small multifamily (2–4 unit) design playbook
Small multifamily lots are usually constrained on width before they're constrained on count. With a 2-unit existing footprint, the binding constraint becomes side-yard setbacks (4 ft min) and the 18-ft height limit. Two-story stacked-flat ADUs over surface parking are the highest-yield typology.
Pro-forma snapshot
| Existing units | 2 |
| Detached ADUs (SB 1211) | 2 |
| Interior conversions | 1 |
| Total new units | 3 |
| Median 1BR rent in Fontana | $1,900/mo |
| Est. additional gross rent | $68K/yr |
| Estimated total project cost | ~$806K |
| Year-1 NOI estimate | ~$51K |
| Stabilized cap rate at cost | 6.3% |
| Replacement parking required | No (§66313) |
| Approval pathway | Ministerial · §66314 |
| Typical permit timeline in Fontana | 60-100 days |
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