SB 1211 for Fourplex / 4-unit in Ontario

Own a fourplex / 4-unit in Ontario? SB 1211 lets you stack 5 new units on top of your existing 4: 4 detached + 1 interior. At Ontario's median rent of $1,900/mo, that's ~$114K in additional gross annual rent.

5new homes possible
4detached ADUs
1interior conversions
$114Kest. annual rent

The Ontario scenario

Picture the typical case: a 4-unit fourplex / 4-unit on a Ontario block built between 1955 and 1975, with surface parking that hasn't been fully utilized in years. SB 1211 turns that parking into 4 detached units plus 1 interior conversion — 5 new doors that didn't exist before 2024.

Ontario-specific note: Logistics hub demand driving rents up.

Small multifamily (2–4 unit) design playbook

Small multifamily lots are usually constrained on width before they're constrained on count. With a 4-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 units4
Detached ADUs (SB 1211)4
Interior conversions1
Total new units5
Median 1BR rent in Ontario$1,900/mo
Est. additional gross rent$114K/yr
Estimated total project cost~$1,344K
Year-1 NOI estimate~$86K
Stabilized cap rate at cost6.4%
Replacement parking requiredNo (§66313)
Approval pathwayMinisterial · §66314
Typical permit timeline in Ontario60-100 days

Get a personalized SB 1211 feasibility report for fourplex / 4-unit owners in Ontario

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

Other property types in Ontario

Duplex in Ontarioup to 3 new homesTriplex in Ontarioup to 4 new homes5-unit apartment in Ontarioup to 6 new homes6-unit apartment in Ontarioup to 7 new homes8-unit apartment in Ontarioup to 10 new homes10-unit apartment in Ontarioup to 10 new homes12-unit apartment in Ontarioup to 11 new homes16-unit apartment in Ontarioup to 12 new homes20-unit apartment in Ontarioup to 13 new homes24-unit apartment in Ontarioup to 14 new homes32-unit apartment in Ontarioup to 16 new homes

Fourplex / 4-unit owners in other Inland Empire cities

Fourplex / 4-unit in Riverside~$108K/yr rent · 60-100 daysFourplex / 4-unit in San Bernardino~$102K/yr rent · 60-100 daysFourplex / 4-unit in Palm Springs~$132K/yr rent · 70-120 daysFourplex / 4-unit in Murrieta~$120K/yr rent · 60-100 daysFourplex / 4-unit in Temecula~$126K/yr rent · 60-100 daysFourplex / 4-unit in Corona~$120K/yr rent · 60-100 daysFourplex / 4-unit in Moreno Valley~$114K/yr rent · 60-100 daysFourplex / 4-unit in Fontana~$114K/yr rent · 60-100 daysFourplex / 4-unit in Rancho Cucamonga~$126K/yr rent · 60-100 daysFourplex / 4-unit in Victorville~$102K/yr rent · 60-100 daysFourplex / 4-unit in Hesperia~$102K/yr rent · 60-100 days

Topics relevant to this scenario

ADU design under SB 1211Short-term rentals and SB 1211SB 1211 and affordable housingSB 1211 in the coastal zoneSB 1211 in historic districtsSelling SB 1211 ADUs separatelySB 1211: first steps for ownersCommon SB 1211 mistakes