Zoning fundamentalsExplainer

Parking minimums, explained

Most zoning rules cap what you may build. A parking minimum makes you build something — and on a city lot, the stalls can decide the project before the envelope does.

What the rule asks for

spaces requiredunitsthe district’s ratio

less every reduction the site qualifies for

Worked example: 12 units on a 50 × 150 ft lot, 7,500 sq ft. The ratios, the stall dimensions and the reductions are Chicago’s, each linked to Title 17 in our hosted zoning code. Other cities treat minimums very differently — some have none at all; see the “Elsewhere” note.

What it costs

A parking space is a piece of the lot

Chicago’s design standard for a 90-degree stall is 8 ft wide by 18 ft deep, served by a 22 ft aisle §17-10-1001. What that costs the lot depends on how the car reaches it. A stall backed straight onto the alley maneuvers in the alley, so it takes only its own 144 sq ft. A stall reached from a drive aisle inside the lot carries half of that aisle as well, about 232 sq ft.

Alley frontage runs out first. This 50 ft frontage takes 6 stalls along the alley, 864 sq ft in all. At one space per unit, 12 units needs 12 stalls, so the other 6 go in a second row with an aisle between them: a field 48 × 58 ft, about 2,784 sq ft or 37% of this 7,500 sq ft lot. That is ground the building, the yard and the landscaping never get.

The minimum, parked

12 spaces

A 50 by 150 foot lot seen from the alley, holding a building at the street and 12 parking stalls in two rows at the rear, with a drive aisle between them. 12 stallsalley

Two rows of 6 at the rear with the aisle between them, reached from the alley. The building gets the front 74 ft of the lot and no more.

Transit-served

0 required

The same lot with no required parking: the building runs 28 feet deeper and the rear is open ground. openalley

Near rail or a listed bus corridor the same 12 units can be built with no parking at all §17-10-0102-B — and the ground goes back into the building, the yard, or the pro forma.

Same lot, same unit count. Parking is rarely priced into a site until it eats the plan. Heights are drawn to scale.

Trigger

When the standards apply

  • New buildings and new uses, in every district §17-10-0101.
  • Added dwelling units — but only for the units added. A lawful existing deficit need not be cured; it just may not get worse. If the building has stood 20 years or more, the standards bite only when two or more units are added §17-10-0101-B.
  • Nonresidential expansions of 15% or more — floor area, seats, employees, whatever the ratio is measured in — or 25% for a building in lawful existence 50 years or more, and then only for the expanded area §17-10-0101-B.
  • A change of nonresidential use, and only to the extent the new use needs more than the last one would have §17-10-0101-C.
  • Not conversion units or coach houses, which may be established with no parking of their own §17-9-0131 §17-9-0201-F. See coach houses and conversion units.

Bicycle parking runs alongside the car ratios: one space per two car spaces in buildings of eight or more units, and at least one per dwelling unit anywhere near transit §17-10-0102-B.

Chicago

What Chicago requires

UseMinimum parking
Detached house, RS-1 / RS-22 per unit
Detached house, RS-32 per unit
Two-flat, RS-31.5 per unit
Detached house or two-flat, every other district1 per unit
Multi-unit, all R districts1 per unit
Multi-unit, B and C dash-1 through dash-31 per unit
Multi-unit, B and C dash-51 per unit for the first 100 units, then 0.6
Government-subsidized, under 600 sq ft0.33 per unit
Government-subsidized, 600–1,200 sq ft0.70 per unit
Government-subsidized, 1,201 sq ft and up1 per unit
Single-room occupancy1 per 10 units
Elderly housing0.33 per unit

Residential ratios from Off-Street Parking Schedule 1 §17-10-0207, which covers the neighborhood (R, B, C and M) districts. Downtown has its own schedule §17-10-0208, and nonresidential uses are set per 1,000 sq ft of floor area.

Apply the ratio to the unit count the district actually allows, not the one you hope for — see how many units can I build?

Relief

Every way the number comes down

RouteWhat it givesSection
Near transitUp to 100% off outside downtown; 50% in D districts and near Metra, and more than that only by administrative adjustment with 10 days’ notice to the alder§17-10-0102-B
Narrow lot, no alleyNo parking at all for a detached house on a lot of record 33 ft or less in width without improved alley access — and for a two-flat as well, outside RS-1 and RS-2§17-10-0207
Chicago LandmarkNo additional parking to rehabilitate or reuse a landmark, or a contributing building in a landmark district; up to 50% off for National Register buildings§17-10-0102-A
Small requirement, downtownWaived entirely when the requirement comes to fewer than 5 spaces in D dash-5, 10 in dash-7 and dash-10, or 50 in dash-12 and dash-16§17-10-0102-E
Underground parking, downtown50% off in D districts when every space is underground§17-10-0102-C
Small units, downtownUp to 25% off for a D-district building of 100 or more units averaging under 800 sq ft§17-10-0102-D
Accessible (Type A) unitsNo more than 1 space per 8 ft of alley frontage when the building uses the Type A unit incentives§17-10-0102-F
Administrative adjustmentHouses and two-flats in RS-1, RS-2 and RS-3 down to 1 space per unit where the reduction yields more usable open space§17-13-1003-CC
VariationUp to 2 spaces in RT-4, RM-4.5 and RM-5, or 5 spaces or 20% in RM-5.5 and above, for a building 50 or more years old; otherwise 1 space or 20%§17-13-1101-C

Exemptions, reductions and relief in Chicago §17-10-0102. Some stack: a National Register rehab near a station can reach zero.

Near rail there is also a ceiling. New residential construction in a B or C district within 2,640 ft of a CTA or Metra station may build no more than 50% of the district minimum — 6 spaces for our 12 units — unless more is approved §17-3-0308. Read transit-served development for the rest of that bargain.

Other cities

Minimums are not universal

Check the current code for your own city before assuming either way — and check the date on whatever summary you are reading.

Questions

Common questions

What is a parking minimum?

A zoning rule requiring a development to build a set number of off-street parking spaces — usually per dwelling unit, or per 1,000 square feet of floor area for commercial uses. It is one of the few zoning rules that forces you to build something rather than limiting what you may build.

How much parking does Chicago require for apartments?

One space per unit in every R district and in B and C districts through dash-3, falling to 0.6 per unit above the hundredth unit in dash-5 districts. Government-subsidized units are set by size, from 0.33 to 1 space; SROs need one space per ten units and elderly housing 0.33 per unit (§17-10-0207).

How much land does a parking space take?

Chicago’s own standard for a 90-degree stall is 8 feet wide by 18 deep, served by a 22-foot aisle (§17-10-1001). A stall backed onto the alley takes only its own 144 sq ft, because the maneuvering happens in the alley rather than on the lot. A stall served by a drive aisle inside the lot carries half that aisle too, about 232 sq ft.

Can I build with no parking at all?

In Chicago, yes, in the right place. Within 2,640 feet of a CTA rail station entrance or 1,320 feet of a listed bus corridor, the minimum may be reduced by up to 100% outside downtown (§17-10-0102-B). A detached house on a lot of record 33 feet or narrower with no improved alley also needs none.

Does adding units to an existing building trigger parking?

Yes, but only for the units you add, and a lawful existing deficit does not have to be cured — it just may not get worse. If the building has stood 20 years or more, the standards apply only when two or more units are added (§17-10-0101-B). Conversion units and coach houses are excused outright (§17-9-0131, §17-9-0201-F).

What if the parking simply does not fit?

That is what the relief routes are for: an administrative adjustment, or a variation from the Zoning Board of Appeals — which for a building 50 years or older can reach 5 spaces or 20% in the larger RM districts (§17-13-1101-C). See zoning relief in Chicago.

Do parking minimums still exist everywhere?

No. Since 2017 a number of US cities have abolished minimums citywide, and many more have dropped them downtown or near transit. Chicago has not: it keeps the minimums and discounts them heavily near transit.

Keep reading

For a real address

Check the real numbers for a real parcel

LotGrade applies the district’s parking ratio to the unit count for any Chicago address, flags the transit-served reduction where the parcel qualifies, and shows the result next to the buildable envelope and the pro forma.

Analyze a Chicago address Book a walkthrough

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