Does RM-4.5 allow a two-flat?

Two-flats and larger multi-unit buildings are permitted — RM-4.5 allows multi-unit residential and townhouses.

How many units can I build on a standard lot in RM-4.5?

A standard 25 × 125 ft Chicago lot (3,125 sq ft) divided by the 700 sq ft lot-area-per-unit standard permits 4 units by right. Transit-served lots may qualify for Connected Communities density bonuses.

How tall can I build in RM-4.5?

47 feet (§17-2-0311-A). Taller buildings need a variation, a planned development, or — on transit-served B-3/C-3 lots — the Connected Communities height bonus.

Can I add a coach house or conversion unit in RM-4.5?

Yes — the §17-2-0207 use table permits both by right in RM-4.5, citywide (no ADU-area restriction). A building that has lawfully existed 20+ years can add conversion units equal to 33% of its existing units — minimum one (§17-2-0303-C). Coach houses must meet the standards of §17-9-0201-F.

Do parking requirements in RM-4.5 change near transit?

Yes. The base requirement is 1 space per unit, but under the Connected Communities ordinance (§17-10-0102-B) lots within ½ mile of a CTA or Metra rail station — or ¼ mile of a designated bus corridor — can reduce residential parking minimums, up to 100% by right for CTA-rail- and bus-served lots outside downtown districts.

Chicago zoning district · Residential Multi-Unit

RM-4.5 zoning in Chicago: what you can build

RM-4.5 (Residential Multi-Unit 4.5) is a multi-unit residential district allowing multi-unit residential and townhouses, with a maximum floor area ratio (FAR) of 1.7, a height limit of 47 feet, 700 square feet of lot area required per dwelling unit. A standard 25 × 125 ft lot (3,125 sq ft) yields 4 units by right under the lot-area-per-unit standard.

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 →

Where RM-4.5 is mapped

The interactive map needs JavaScript. See the official City of Chicago zoning map instead, or browse every district as text below.

Planned Manufacturing (PMD)
Parks & Open Space (POS)
Planned Development (PD)
Downtown (DC/DR/DS/DX)
Residential (RS/RT/RM)
Business (B)
Commercial (C)
Manufacturing (M)
Transportation (T)
Other / unclassified

Zoning district boundaries: City of Chicago Data Portal. Basemap: © OpenFreeMap © OpenMapTiles © OpenStreetMap contributors.

RM-4.5 bulk & density standards

RM-4.5 — Residential Multi-Unit 4.5 · Municipal Code of Chicago, Title 17
Maximum floor area ratio (FAR)	1.7 verified §17-2-0304-A, Municipal Code of Chicago
Maximum building height	47 ft verified §17-2-0311-A, Municipal Code of Chicago
Minimum lot area	1,650 sq ft verified §17-2-0301-A, Municipal Code of Chicago
Lot area per unit (density)	700 sq ft / unit verified ≈ 62.2 units per acre §17-2-0303-A, Municipal Code of Chicago
Setbacks (front / side / rear)	15.1 / 4.9 / 29.9 ft approximation Chicago setbacks are contextual formulas (averages of neighboring lots, % of lot width/depth). These are working scalars — confirm per lot. §17-2-0305..0309, Municipal Code of Chicago
Residential parking	1 space / unit verified Before TOD / Connected Communities reductions. §17-10-0207-C, Municipal Code of Chicago
Maximum lot coverage	60% approximation

Verified figures match the ordinance table verbatim at the cited section. Approximation flags contextual formulas (setbacks that depend on neighboring lots, use-group-dependent parking) reduced to a working scalar — the ordinance formula governs.

Permitted uses

RM-4.5 allows multi-unit residential and townhouses.

multi-unit residential
townhouses

Transit changes these numbers

Under the Connected Communities ordinance (§17-10-0102-B), transit-served lots can cut residential parking minimums — up to 100% by right within ½ mile of a CTA rail station or ¼ mile of a designated bus corridor (outside downtown districts), and up to 50% near Metra. Density and height bonuses, however, are reserved for -3 suffix B and C districts — a residential district like RM-4.5 keeps its base bulk standards. Full Connected Communities guide →

RM-4.5 — common questions

Does RM-4.5 allow a two-flat?: Two-flats and larger multi-unit buildings are permitted — RM-4.5 allows multi-unit residential and townhouses.
How many units can I build on a standard lot in RM-4.5?: A standard 25 × 125 ft Chicago lot (3,125 sq ft) divided by the 700 sq ft lot-area-per-unit standard permits 4 units by right. Transit-served lots may qualify for Connected Communities density bonuses.
How tall can I build in RM-4.5?: 47 feet (§17-2-0311-A). Taller buildings need a variation, a planned development, or — on transit-served B-3/C-3 lots — the Connected Communities height bonus.
Can I add a coach house or conversion unit in RM-4.5?: Yes — the §17-2-0207 use table permits both by right in RM-4.5, citywide (no ADU-area restriction). A building that has lawfully existed 20+ years can add conversion units equal to 33% of its existing units — minimum one (§17-2-0303-C). Coach houses must meet the standards of §17-9-0201-F.
Do parking requirements in RM-4.5 change near transit?: Yes. The base requirement is 1 space per unit, but under the Connected Communities ordinance (§17-10-0102-B) lots within ½ mile of a CTA or Metra rail station — or ¼ mile of a designated bus corridor — can reduce residential parking minimums, up to 100% by right for CTA-rail- and bus-served lots outside downtown districts.