ADU rules in Champaign

Champaign's Zoning Ordinance of 2026 (Council Bill No. 2026-133, passed September 1, 2026 and effective September 2, 2026) replaced the whole of the old Chapter 37 and carried the 2022 ADU rules forward. Table III-C in Section 37-310 marks Accessory Dwelling Units as permitted by right in every residential district: R1, R2, MR1, MR2, MR3, RU1, RU2, IT-R1, IT-R2, IT-MR1, IT-MR2, IT-MR3 and MHC (under Table III-D the old SF1 became R1, SF2 became R2, MF1 to MF3 became MR1 to MR3, and so on). A Detached ADU is a freestanding unit, including one combined with a detached garage, and one ADU of any type is allowed per lot. A detached unit may not sit between the front building line of the house and the front lot line, is capped at 24 feet tall, and must meet the principal-building setbacks of Table IV-A unless it reuses an accessory structure built more than ten years earlier. ADUs are not allowed in any commercial, research park or industrial district, even where a house stands there.

Section 37-201 recognizes two non-detached forms: an Attached ADU that expands the existing house and is self-contained with a separate means of egress, and an Internal ADU wholly inside the existing house, without expanding it, also with its own separate means of egress. Table III-C permits ADUs as a single use without distinguishing type, so basement, addition and internal conversions are allowed in the same thirteen residential districts as backyard cottages. Under Section 37-501(5) and (6), attached and internal units follow the setback and height limits of Table IV-A for the district (36 feet in R1 and R2) instead of the 24 foot detached cap, and they count toward the floor area ratio, open space ratio, lot coverage and building footprint limits. The same 600 or 800 square foot cap and one per lot limit apply.

Section 37-501(2) ties the cap to lot area alone, measured as gross floor area to the outside walls, with no percentage-of-house test. The text gives 600 square feet to lots 'with less than 7,200 square feet in area' and 800 square feet to lots 'greater than 7,200 square feet in area', so a lot of exactly 7,200 square feet falls in neither clause; ask the Zoning Administrator. Detached ADUs are capped at 24 feet; attached and internal units take the district height limit. A detached ADU may be combined only with a detached garage: the living space counts against the ADU cap, the garage counts against the accessory structure allowance in Section 37-418(1)(e) (50 percent of the house's gross floor area, or up to 650 square feet when the house is under 1,300 square feet), and the ADU portion may never exceed the ADU size allowance.

The Zoning Ordinance of 2026 imposes no owner occupancy condition on an ADU, at application or afterward. Section 37-501 runs from (1), one unit per lot, through (13), building code compliance, and never mentions owner occupancy, carrying forward the 2022 rules, which never had one. The new ordinance knows how to require it when it wants to: Section 37-532(1)(a) requires a bed and breakfast in R1 to be 'owner-occupied' with the owner as operator, and that is the only owner occupancy clause in the chapter. Illinois has no statewide ADU statute, so nothing would preempt a local owner occupancy rule; Champaign simply has not adopted one.

Section 37-602 of the Zoning Ordinance of 2026 states 'No off-street vehicle parking is required for any use in the City of Champaign,' so neither the ADU nor the house has to provide spaces. This replaces the old ADU-specific waiver, which worked only if the house already had its own two off-street spaces. Bicycle parking is not required either: Table VI-B does not list ADUs, and Section 37-611(1)(a) requires residential bicycle parking only in principal buildings with an elevator. If you choose to build a driveway or parking pad, the Article VI design rules still apply when such facilities are provided (Sections 37-603(1) and 37-620). Separately, the state People Over Parking Act (Public Act 104-0457, Article 5, effective June 1, 2026) bars parking minimums near transit, but Champaign's citywide repeal already goes further.

Table III-C marks ADUs with a check, which Section 37-309(2) defines as 'permitted by right in the subject zoning district', so there is no public hearing, special use permit or Plan Commission action. Section 37-501(13) requires the unit to comply with all building code requirements and be approved for a building permit before construction, and under Sections 37-1102 and 37-1103 the Zoning Administrator reviews each building permit application, with a scaled site plan, for zoning compliance before it issues. The planning and zoning fee schedule in Section 19-8.15 carries no ADU fee; ordinary one and two family building permit fees and a five business day plan review target apply. One overlay adds discretion: on a designated Landmark or in a Historic District any exterior construction, and in a Conservation District any new building, needs a Certificate of Appropriateness, which staff may issue only for work needing no building permit or for roof, window and door replacement, so an ADU there goes to the Historic Preservation Commission.

Nothing in the Zoning Ordinance of 2026 bars renting an ADU, and there is no primary-residence test. Section 37-501(10) caps occupancy at 'no more than two (2) persons unrelated to each other by blood, marriage or legal adoption', tighter than the general family definition in Section 37-206(3), which allows up to four unrelated people, and that matters in a university town. Section 37-501(11) bans home occupations and any other business use inside the ADU, and Section 37-501(12) bars selling the ADU separately from the house. Since Council Bill No. 2026-052 (April 21, 2026), every rented dwelling unit, expressly including accessory dwelling units and short-term rentals regardless of lease duration, must be registered with the Neighborhood Services Department and renewed by March 1 each year, with enforcement starting March 1, 2027. The zoning ordinance neither licenses nor names short-term rental of an ADU; its only transient lodging use in residential districts is a bed and breakfast, a detached dwelling renting bedrooms to overnight guests, which in R1 must be owner-occupied.