Draft Language for Allowing Coach Houses in Chicago - Metropolitan Planning Council

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Draft Language for Allowing Coach Houses in Chicago

MPC's recommendations for allowing coach houses in Chicago to the Mayor's Zoning Reform Commission, including requirements and draft language for coach houses.


Chicago’s current zoning ordinance does not allow coach houses, a building type that is already prevalent in many neighborhoods. Coach houses contribute a mix of housing types and additional rental units in single-family neighborhoods in Chicago, and should be readmitted to standard development practices in the new ordinance. MPC provides the following draft language to permit hopes of working together with the Mayor’s Zoning Reform Commission and the Department of Planning and Development to arrive at an acceptable coach house policy that can be added to the new code. The following document contains a summary of recommended requirements for coach houses followed by draft language.

Suggested requirements for coach houses:

  • Coach houses will be limited to RS 1-3 districts.
  • One coach house unit per lot permitted.
  • Coach houses permitted on lots 30 feet or more in width, and 150 feet or more in depth.
  • Property owner must occupy either the principle building or the coach house.
  • Coach houses shall be allowed as of right provided that satisfactory administrative review, site plan review and property inspection are conducted; and zoning and building code regulations are met.
  • Coach houses should be limited to a separate structure with 75 percentof its floor area over the garage to preserve on-site parking.
  • No on-site parking required for coach houses.
  • Entrances to coach house may be in alley or in rear yard.
  • Mailbox and doorbell to identify coach house must exist at street frontage.
  • Amnesty should be given for one-year or other grace period for illegal units to apply for permit, and/or come up to code.

Draft Language for Consideration

A homeowner may establish, on any zoning lot 30 feet or more in width and 150 feet or more in depth in an RS district with access to an improved rear alley, one dwelling unit in one detached accessory structure within the rear setback, provided that the accessory structure meets the following standards:

1. Subordination. The accessory structure shall be clearly subordinate to the principle structure in use and appearance.

2. Placement. The accessory structure shall be at least 50 feet from the front lot line, and shall comply with the required rear setback and open space standards in Sec. 17-2-0306. No rear setback is required between an alley and an accessory structure.

3. Floor Area. The accessory structure shall not have a floor area of less than 300 square feet or more than 900 square feet, or 30 percent of the lot coverage of the principle structure, whichever is less. The floor area ratio of the accessory dwelling unit shall not be included in floor area calculations of the principle residence. An accessory dwelling unit may be located over enclosed parking, loading, or access areas. Floor area shall be calculated using the standards set in the section 17-2-0304-C.

4. Height. The accessory structure shall be proportional in height to the principle building; 75 percent of the main structure or three floors including the garage level, whichever is less.

5. Setbacks. The accessory structure shall not encroach into required side setbacks, except as allowed in section 17-2-0308. Unenclosed stairs providing primary or secondary access to the accessory dwelling unit may encroach into side or rear yard setbacks.

6. Rear Yard Open Space. The accessory structure shall not encroach into required rear yard open space.

7. No Separate Sale. The accessory structure and the lot underneath the principle structure may not be under separate ownership.

8. No Parking. No off-street parking shall be required for an accessory dwelling unit.

9. No Minimum Lot Area Per Dwelling. The accessory dwelling unit shall not be required to conform to the minimum lot area per unit standards.

10. Entrances. Entrances to a coach house may be in the rear yard or on the alley, provided that the doorbell and mailbox to identify the rear coach house is located within the street frontage or on the principle structure.

11. Otherwise Conforming. The accessory structure shall conform to applicable housing and building codes.

12. Upon passage of this ordinance, existing illegal coach houses shall have one year to comply with all applicable codes and regulations.

Issues for Consideration



  • Encourage efficient use of existing housing stock and infrastructure; encourage housing maintenance and neighborhood stability (owners can apply a portion of the rental income to maintaining the property); 
  • Extra income allows homeowners to age in place, remain in their homes for longer periods of time (especially important to elderly, single parent families), and meet any rising homeownership costs (property tax increases, maintenance expenditures); 
  • Enhances security of property with presence of tenants when homeowner is away. 
  • For young or first time buyers, existence of an accessory dwelling unit may allow them to qualify for larger mortgage loans and rental of the unit could offset high mortgage payments.


  • Coach houses typically rent for less than market rate, as they are less expensive to build and require no new land development.
  • Lower rents for coach houses may allow tenants to save for a down payment on a home of their own. High rents often make it difficult to save enough for the required down payment. 
  • Coach houses offer more choice for living in single-family neighborhoods for moderate-income people who may otherwise be forced to live in apartment complexes.


  • Coach houses and other accessory dwelling units provide a means of increasing the supply of housing without increasing government subsidies.
  • Coach houses allow for a mix of housing that responds to changing family needs.

Potential Studies Needed

  • Log of currently existing coach houses (both legal and illegal; illegal units may indicate pent up demand);
  • Estimate of expected demand for coach houses if policy goes through (inventory of existing housing stock, rental vacancy rates, how many properties have right dimensions, etc. that would allow coach house development); 
  • Study in Year 1 or 2 following policy’s passage to determine number of units built, rental prices, if existing policy is sufficient or if it has had unexpected consequences that may require tinkering with existing policy. 
  • Existing 150 foot lot survey.

Potential Definitions

A) An accessory dwelling unit (ADU) is a habitable living unit added to, created within basement apartments, or detached from a single-family dwelling that provides basic requirements for living, sleeping, eating, cooking and sanitation. [Sec. 19.04.0607(B) Mercer Island Code.]

B) “Coach House” means a dwelling unit, which has at least 75 percent of its floor area located above a garage, which may be detached or attached to a principle dwelling. [Richmond, Canada]

Fire Code Issues

Austin, Milwaukee and Sheboygan, Wis. have coach houses off their alleys and experience no issues with their respective fire departments as a result. The average width of the alleys in these cities is 15 to 16 feet. In addition, Portland, Ore. has many "granny flats," considered "very common and allowed in the zoning ordinance". Portland’s alleys are 14 to 20 ft. wide and raised no problems with the local fire department.


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