RT-4A Residential Two-Flat, Townhouse and Multi-Unit District
Two-flats, townhouses and low-density apartment buildings. RT districts accommodate a mix of housing types at moderate density, with RT-4A offering bonus floor area for projects that include accessible units.
Example on a 25 × 125 ft lot. The dashed box is the maximum zoning envelope, the buildable footprint after setbacks, raised to the 42 ft height limit. The solid building is an illustrative example at FAR 1.2: covering the full footprint reaches only ~2 stories before the floor-area cap binds, so a taller building needs a smaller floor plate. Residential floors sit over a partially above-grade basement, which counts toward height but not floor area. Front yard is context-dependent (average of adjacent lots); actual varies.
Specifications
- Zoning Ordinance reference
- §17-2-0100
View in the Chicago Zoning Ordinance - Floor area ratio (FAR)
- 1.2 (up to 1.5 with bonus)
- Maximum building height
- 42 ft, measured to the top floor's ceiling (flat roof) or mean roof height (pitched roof). §17-17-0311.
- Lot area per unit (density)
- 1,000 sq ft of lot area per dwelling unit. 1,000 sq ft per efficiency unit; 500 sq ft per SRO unit.
- Minimum lot area
- 1,650 sq ft
- Rear yard open space
- The greater of 65 sq ft per unit or 6.5% of lot area, containing a circle at least 12 ft in diameter. Must sit in the rear yard, at or within 4 ft of grade. §17-2-0307.
- On-site open space
- —
- Parking requirements
- 1 space per dwelling unit. §17-10-0207.
Setbacks
- Front yard
- The lesser of 15 ft or 12% of lot depth, or the average of the adjacent lots. §17-2-0305.
- Side yard
- Combined at least 20% of lot width; each side at least 2 ft or 8% of width (no side required to exceed 5 ft). §17-2-0309.
- Rear yard
- The lesser of 50 ft or 24% of lot depth (under 20 units); 30% of depth for 20 or more units. §17-2-0306.
Allowed Uses
Curated from the §17-2-0207 use table. P = permitted by-right; S = special-use approval required. Always confirm against the full ordinance text.
- Detached house
- Two-flat
- Townhouse
- Multi-unit (3+) residential
- Elderly housing
- Single-room occupancy (RT4)
- Conversion unit & coach house
- Day care; schools; religious assembly
- Parks & recreation; community gardens
- Cultural exhibits & libraries; hospital (RT4)
- Bed & breakfast (RT4); vacation rental
- Community home (group)
- Domestic violence residence / shelter (RT4)
- Nursing home / group living (RT4)
- Temporary overnight shelter; transitional shelters
- Lodge or private club (RT4)
- Community / recreation centers; police station
- Major utilities; non-accessory parking
- Freestanding wireless towers
Reference figures are modeled from the Chicago Zoning Ordinance (Title 17) for general guidance and do not constitute zoning or legal advice. Lot-specific limits depend on frontage, depth, adjacencies and overlays — analyze a specific address for exact figures. Always confirm against the official ordinance.