ADU rules in Aurora

Aurora's zoning ordinance has no accessory dwelling unit anywhere in it, and it affirmatively bars a second dwelling building on a lot. Sec. 49-103.2 (Rules, General Provisions, 'Buildings on a Zoning Lot') allows no more than one building providing dwelling units on one zoning lot, and each single-family district repeats the point: 'Only one (1) principal building shall be allowed on a zoning lot' appears verbatim in the E, R-1, R-2 and R-3 districts (Secs. 49-107.4 through 49-107.7), each followed by 'All single family detached dwelling units shall be constructed on a single recorded lot.' The two backyard structures that come closest are expressly not dwellings: a 'guest house (without kitchen)' for occasional guests, and second-floor quarters in a two-story garage that 'may be occupied by a domestic employee (and his family) of the family occupying the main structure.' Table Four, which is the exhaustive list of accessory structures permitted in the E, R-1, R-2 and R-3 districts, has rows for a detached garage, garden house, gazebo, private greenhouse, shed, pool and playhouse, and no row for living quarters of any kind.

An internal or attached second unit is just as unavailable in the single-family districts. Sec. 49-103.3 defines 'Dwelling, One-Family' as 'A building designed exclusively for use and occupancy by one (1) family, and entirely separated from any other dwelling by space', so finishing a basement, attic or addition as an independent unit converts the house into a 'Dwelling, Two-Family', defined as 'A building designed or altered to provide dwelling units for occupancy by two (2) families.' Table One: Use Categories permits use 1120 Two Family Dwelling only in the R-4 and R-4A districts; the E, R-1, R-2 and R-3 cells are blank, and the table's own key reads a blank cell as 'Use Not Permitted'. Even in R-4 and R-4A what is allowed is a duplex, two co-equal units in one building, not a subordinate accessory unit, because Aurora's code has no accessory dwelling concept to be subordinate to anything. Aurora also defines 'Family' narrowly, as persons related by blood, marriage or adoption or a group of no more than three unrelated persons, which limits how far a single lawful unit can stretch.

Because Aurora authorizes no accessory dwelling, there is no floor area cap, no percent-of-primary-dwelling ratio and no ADU height limit to report. The nearest numbers govern uninhabitable accessory buildings. Sec. 49-104.4(f) provides that 'No private detached garage structure shall exceed seven hundred sixty eight (768) square feet' with no single wall over 36 feet, that 'A private detached garage shall not exceed seventy-five percent (75%) of the foundation area of the principal building', and that it 'shall not exceed the height of the principal building or 21', whichever is less', with vertical sidewalls no taller than 9 feet and storage above the first story limited to 50 percent of the first floor's cubic volume. Sheds are held to 160 square feet, 14 feet in height, 8 feet of wall height and a 16 foot maximum wall length. Each zoning lot of record gets a maximum of one shed and one garage per residential dwelling. None of these may contain a dwelling unit.

The question does not arise in Aurora: there is no ADU for an owner-occupancy condition to attach to, and Chapter 49 states no owner-occupancy covenant, affidavit or recorded-restriction regime for any residential use. The two accessory living arrangements the ordinance does contemplate are tied to the household rather than to ownership. Garage quarters are limited to 'a full-time employee hired to perform routine household duties (and his or her family) for occupants of the principal dwelling, while receiving compensation for their work', and a Guesthouse serves 'contemporary guests of the occupants of the premises'. Both presuppose that the main house is occupied, but neither requires that occupant to be the owner. Recorded as unknown rather than yes or no because there is no ADU rule to characterize, not because the text is ambiguous.

Table Two: Schedule of Off-Street Parking Requirements has no accessory dwelling row. It assigns single-family buildings and detached units '2 enclosed spaces per dwelling unit', raises that in the E Estate district to '3 enclosed spaces per dwelling unit, which shall be attached to the principal building', and applies the same 2 enclosed spaces per unit to duplex structures and to zero lot line and row houses. Because the requirement is stated per dwelling unit and demands enclosure, any second unit Aurora did permit would bring its own two-car garage obligation, which is a heavier burden than the single surface space typical of ADU ordinances elsewhere. Separately, Aurora's residential rental licensing program requires a minimum of 2 off-street spaces per dwelling unit for licensed single-family and two-family rental housing. PA 104-0457, Art. 5 (People Over Parking Act), effective 6-1-2026, bars any unit of local government from imposing or enforcing minimum automobile parking requirements on a development project (a permit to construct or reconstruct a dwelling qualifies) within one-half mile of a public transportation hub (any rail transit station, or an intersection of 2 or more bus routes with combined 15-minute peak frequency) or one-eighth mile of a 15-minute-peak bus corridor, binds home-rule units (Section 5-90), and grandfathers site plans approved before the effective date (Section 5-15(b)). It creates no ADU right in Aurora, but it qualifies the baseline minimums stated here: the Aurora Transportation Center Metra station is a rail transit station, so within a half mile of it (and of the Route 59 station on the Naperville boundary) the two-space minimum cannot be imposed or enforced on new dwelling construction; bus-frequency tests were not verified.

There is no ADU permit path to classify. Accessory dwellings are absent from Table One: Use Categories entirely, so no by-right zoning permit, no conditional use and no administrative review exists for one. A homeowner who wanted a lawful second unit would have to change the zoning rather than apply for a permit: either a map amendment to R-4 or R-4A, where use 1120 Two Family Dwelling is permitted by right, or a conditional use planned development whose plan description sets the site's own use list, both under the Chapter 34 procedures that Sec. 49-103.2 incorporates. The City's own FAQ puts rezonings, conditional uses and annexation agreements at 60 to 90 days from formal submittal, and Aurora's Legistar record shows conditional use planned developments approved by City Council ordinance several times a year. Recorded as unknown rather than conditional-use because those are rezoning and planned development routes, not an ADU approval process.

Aurora's ban on renting accessory living space is explicit rather than implied. Sec. 49-103.3 defines a Guesthouse as living quarters in a detached accessory building 'for use by contemporary guests of the occupants of the premises' and adds that 'Such quarters shall have no kitchen facilities nor be rented or otherwise used as a separate dwelling.' Sec. 49-103.2 makes the same point from the other direction, permitting guest rooms only for 'the occasional housing of guests of the occupants of the main structure and not for permanent occupancy by others as a housekeeping unit.' The garage-quarters carve-out is not a rental either, since it is limited to a full-time household employee 'while receiving compensation for their work'. Full-code searches on 2026-08-07 returned no exact match for 'short term rental', 'coach house' or 'carriage house' anywhere in the Aurora Code of Ordinances, so there is no local short-term rental licensing regime to report. Renting any lawful dwelling in Aurora does require a residential rental license from the Division of Property Standards, under the rental ordinance changes adopted by Ord. No. O18-049 (passed 6/12/2018) and in effect since 12 June 2018.