Chicago zoning comparison · where the two-flat becomes legal
RS-2 vs RS-3: which lets you build more?
RS-3 carries the larger envelope — FAR 0.9 vs 0.65; on a standard 25 × 125 ft Chicago lot, RS-3 permits 1 unit by right against 0.
Figures originally read from a Title 17 excerpt in a third-party zoning report dated 18 September 2024. On 24 August 2026 the bulk standards — floor area ratio, lot area per unit, building height and minimum lot area — were re-checked against the current adopted edition 2026-S-73 and found unchanged. Setbacks and parking ratios were not part of that pass and still rest on the 2024 reading. Data snapshot generated 2026-08-24. How this data is produced and checked →
Side by side
| RS-2 Residential Single-Unit (Detached) 2 | RS-3 Residential Single-Unit (Detached) 3 | |
|---|---|---|
| Max FAR | 0.65 | 0.9 |
| Max height | 30 ft | 30 ft |
| Lot area per unit | 5,000 sf | 2,500 sf |
| Units on a standard 25×125 ft lot | 0 | 1 |
| Min lot area | 5,000 sf | 2,500 sf |
| Residential parking / unit | 2 | 2 |
| Max lot coverage | 40% | 45% |
| Permitted uses | detached single-family homes | detached single-family homes and two-flats |
| Connected Communities bulk bonus tier | No | No |
Green marks the more permissive value. Setbacks are contextual in both districts and omitted here — see the district pages for the working scalars and the governing formulas.