17-17-0300  Measurements.
   17-17-0301 Division of Improved Zoning Lots. No improved zoning lot may be divided into 2 or more zoning lots and no portion of any improved zoning lot may be sold unless all improved zoning lots resulting from the division or sale comply with all the applicable bulk regulations of the zoning district in which the property is located.
   17-17-0302 Lot Area.Lot area includes the total land area contained within the property lines of a lot.
   17-17-0303 Lot Frontage. Lot frontage is measured between side property lines along the front property line abutting a public street.
   17-17-0304 Lot Area per Unit. Lot area per unit refers to the amount of lot area required for each dwelling unit on the property. For example, if a minimum lot-area-per-unit standard of 1,000 square feet is applied to 3,125 square foot lot, a maximum of 3 dwelling units would be allowed on the property.
   17-17-0305 Floor Area Ratio. The floor area ratio of a building is the floor area of the building divided by the total gross area of the zoning lot upon which the building is located. In the case of planned developments and townhouse developments, the floor area ratio of a building site is the floor area of all buildings on the site divided by the net site area of the building site.
      17-17-0305-A For the purpose of calculating floor area ratios, the “floor area” of a building is the sum of the gross horizontal area of all floors in the building measured from the exterior faces of the exterior walls or from the center line of walls separating two buildings. The “floor area” of a building expressly includes all of the following:
         1.   floor area of any floor located below grade or partially below grade when more than one-half the floor-to-ceiling height of the below-grade (or partially-below-grade) floor is above grade level, provided that below-grade or partially below-grade floors with a clear height of less than 6 feet 9 inches are not counted as floor area;
Figure 17-17-0305-A1
         2.   elevator shafts and stairwells on each floor;
         3.   floor area used for mechanical equipment, except equipment located on the roof and mechanical equipment within the building that occupies a commonly owned contiguous area of 5,000 square feet or more;
         4.   those portions of an attic having clear height (head-room) of 6 feet 9 inches or more;
Figure 17-17-0305-A4
         5.   mezzanines;
         6.   enclosed porches;
         7.   floor area devoted to non-accessory parking;
         8.   parking provided in excess of the maximum accessory parking limits established in Sec. 17-10-0208, provided that each such parking space will be counted as 350 square feet of floor area; and
         9.   floor area within a principal building that is occupied by accessory uses.
      17-17-0305-B For the purpose of calculating floor area ratios, floor area devoted to required loading, accessory parking and the drive aisles and circulation area associated with such loading and parking are not to be counted as “floor area”.
   17-17-0306 Front Setbacks.
      17-17-0306-A Measurement. Required front setbacks and existing average front yards are to be measured from the front property line of the lot on which such building is located to the exterior wall of the building.
      17-17-0306-B Permitted Obstructions / Encroachments. Required setbacks must be unobstructed and unoccupied from the ground to the sky except as expressly allowed in Sec. 17-17-0309. All portions of required front setbacks that are not occupied by permitted obstructions (See Sec. 17-17-0309) must be landscaped and preserved as open space.
      17-17-0306-C Patio Pits. No terrace or patio more than 2 feet below grade is permitted within 15 feet of the front property line in any RS1, RS2 or RS3 district or within 12 feet of the front property line in any other R district. This provision is not intended to prohibit the installation of a terrace or patio on a lot that has a pre-construction grade more than 2 feet below the top of the curb of the street upon which the lot fronts. Patios or terraces more than 2 feet below grade may be constructed in the front yard outside of the required setback distance established in this section only if such terrace or patio is visually screened from view with landscaping and decorative fencing.
      17-17-0306-D Negative Grade Elevation Lots and Allowed Uses. When the existing streetgrade (curb level) has a positive (+) elevation above the established lot grade and there is no requested negative (–) elevation change or lowering of the established lot grade within the front setback; then, a terrace or patio may be allowed provided that the area within the terrace or patio is landscaped and preserved as open space. A decorative fence must be installed at the front property enclosing the front setback.
   17-17-0307 Rear Setbacks.
      17-17-0307-A Measurement. Required rear setbacks are to be measured from the rear property line of the lot on which such structure is located to the furthermost projection of the structure, not including those projections and features allowed within such setback pursuant to Sec. 17-17-0309.
      17-17-0307-B Permitted Obstructions / Encroachments. Required setbacks must be unobstructed and unoccupied from the ground to the sky except as expressly allowed in Sec. 17-2-0306-D Sec. 17-2-0306-E or Sec. 17-17-0309.
   17-17-0308 Side Setbacks.
      17-17-0308-A Measurement. Required side setbacks and existing side yards are to be measured from the side property line of the lot on which such structure is located to the furthermost projection of the structure, not including those projections and features allowed within such setback pursuant to Sec. 17-17-0309.
      17-17-0308-B Permitted Obstructions / Encroachments. Required setbacks must be unobstructed and unoccupied from the ground to the sky except as expressly allowed in Sec. 17-17-0309.
      17-17-0308-C Division of Improved Zoning Lots. When zoning lots in RS3, RT3.5, RT4, R4.5, RM5, and lots in B and C districts are divided and such lots contain existing attached buildings, side setbacks do not apply between the attached buildings.
   17-17-0309 Features Allowed to Encroach in Required Setbacks. Required setbacks in all districts must be unobstructed and unoccupied from the ground to the sky except that features are allowed to encroach into required setbacks to the extent indicated in the following table:
 
Obstruction/Projection into Required Setback
Front
Side
Rear
Accessory buildings used for domestic storage (e.g., sheds and tool rooms)
No
No
Yes
Air conditioning units, provided the unit is not more than 4 feet in height
No
Yes
Yes
Arbors and trellises
Yes
Yes
Yes
Awnings and canopies
Yes
Yes
Yes
Bay windows that project no more than 3 feet into the setback and are located at least 4 feet above grade at their lowest point
Yes
No
Yes
Chimneys that project no more than 18 inches into the setback
Yes
Yes
Yes
Satellite dish antennas, not exceeding 1 meter in diameter
Yes [1]
Yes
Yes
Satellite dish antennas, over 1 meter but not exceeding 2.4 meters in diameter
No
No
Yes
Eaves and gutters projecting 18 inches or less into setback
Yes
Yes
Yes
Eaves and gutters projecting 3 feet or less into setback
Yes
No
Yes
Fences and walls (no more than 20% opaque) up to 6 feet in height
Yes
Yes
Yes
Fences and walls (more than 20% opaque or solid) up to 4.5 feet in height
Yes
Yes
Yes
Fences and walls (more than 20% opaque or solid) up to 6 feet in height
No
Yes
Yes
Flagpoles
Yes
Yes
Yes
Parking spaces, enclosed, provided that (attached or detached) garages that are accessed from alleys must be set back at least two feet from the rear property line (this two-foot setback is not required if the garage is located at least 10 feet from the centerline of the alley, as evidenced by a survey or other similar evidence provided by the applicant and deemed acceptable by the Zoning Administrator) provided further, however, that additions following the rear wall of existing garages shall be permitted regardless of the proximity of the existing garage's rear wall to the rear property line
No
No
Yes
Parking spaces, unenclosed in RS districts
No
Yes [2]
Yes
Parking spaces, unenclosed in RT and RM districts
No
No
Yes
Patios that are not over 4 feet above the average level of the adjoining ground (See Sec. 17-17-0306-C)
No
No
Yes
Porches and balconies and that are open on at least 3 sides
No
No
Yes
Recreational equipment (e.g., swing sets and basketball hoops)
No
No
Yes
Roof projecting from garage over open patio not to exceed 8 feet
No
No
Yes
Stairs (unenclosed), providing access to a rooftop deck on an accessory building, with a staircase width not exceeding 4 feet, so long as the entire staircase abuts and is parallel to the wall of the accessory building
No
Yes
Yes
Stairs (unenclosed) providing secondary egress required by the Building Code
No
Yes[3]
Yes
Sills, belt courses, cornices, buttresses and other architectural features projecting no more than 3 feet into the setback
Yes
Yes
Yes
Steps no more than 6 feet above Grade that are necessary for access to a permitted building or for access to zoning lot from a street or alley
Yes
Yes
Yes
Wheelchair lifts and ramps that meet federal, state and local accessibility standards
Yes
Yes
Yes
 
[1]   Subject to the restrictions of Section 17-9-0203-A.
[2]   Permitted only when the parking is accessed from a public street where no alley exists.
[3]   Permitted only for townhouse developments.
   17-17-0310 Building Wall Separation.
      17-17-0310-A Measurement. Required building separations are to be measured between the furthermost projection of the structures, not including those projections and features allowed within such setback pursuant to Sec. 17-17-0309.
      17-17-0310-B Permitted Obstructions / Encroachments. Required separations must be unobstructed and unoccupied from the ground to the sky except as expressly allowed in Sec. 17-17-0309.
   17-17-0311 Building Height.
      17-17-0311-A Measurement. The building height of any principal or accessory building is measured as the vertical distance from grade to the highest point of the underside of the top floor's ceiling joist on a building with a flat roof or to the mean height level between eaves and ridge of a gable, hip, mansard, or gambrel roof. For purposes of this provision, “floor” means any enclosed area with a floor-to-ceiling height of 6 feet 9 inches or more.
Figure 17-17-0311-A
      17-17-0311-B Limitations on Rooftop Features in R Districts.
         1.   Stairway enclosures and elevator penthouses in R districts are allowed to exceed the maximum building height, provided:
            (a)   they are set back at least 20 feet from the front building line, and
            (b)   do not exceed 9 feet in overall height or extend more than 5 feet above the building parapet, whichever results in a lesser height, except that where access to the roof is required under Chapter 14B-11 of the Municipal Code, an elevator penthouse may exceed 9 feet but shall not exceed 15 feet in overall height, and may extend more than 5 feet but shall not extend more than 11 feet above the building parapet, whichever results in a lesser height.
         2.   Stairway enclosures in R districts may not contain habitable space and may not exceed 170 square feet in area.
         3.   Elevator penthouses in R districts may not contain habitable space and may not exceed 465 square feet in area.
         4.   Rooftop wind energy systems shall be considered permitted accessory structures within all districts provided they comply with the height limits and setbacks established in this Section. A rooftop energy conversion system shall consist of a wind turbine(s) and associated equipment for converting wind energy to power. Wind energy conversions systems shall be permitted as rooftop accessory structures provided such structures:
            (a)   are set back at least 20 feet from the front building line, or in the case of corner lots, at least 15 feet from the front and side building line.
            (b)   are limited to a height of no more than 15 feet above the roof or top of the parapet, whichever is greater.
            (c)   comply with all noise limitations of the Chicago Municipal Code.
            (d)   are safely and securely attached to the rooftop in compliance with the Chicago Building Code.
         5.   Pergolas, arbors and trellises located on rooftops of principal buildings and private garages in R Districts are allowed to exceed the maximum building height, provided that:
            (a)   on principal buildings less than 80 feet tall, they are set back at least 20 feet from the front building line, or in the case of comer lots, at least 15 feet from the front and side building lines;
            (b)   on principal buildings and private garages, they do not exceed 11 feet in overall height above the rooftop deck, or extend more than 8 feet above the building parapet, whichever is greater;
            (c)   they are safely and securely attached to the rooftop.
(Added Coun. J. 5-26-04, p. 25275; Amend Coun. J. 3-9-05, p. 44391; Amend Coun. J. 3-29-06, p. 73934, § 1; Amend Coun. J. 9-13-06, p. 84870, §§ 2, 3; Amend Coun. J. 10-31-07, p. 12065, § 1; Amend Coun. J. 10-8-08, p. 40951, § 1; Amend Coun. J. 5-12-10, p. 92103, § 1; Amend Coun. J. 4-13-11, p. 115858, § 1; Amend Coun. J. 11-2-11, p. 12143, § 1; Amend Coun. J. 3-14-12, p. 23152, § 2; Amend Coun. J. 3-29-17, p. 45477, §§ 7, 8; Amend Coun. J. 2-19-20, p. 14473, Art. VI, § 28)