ADU rules in Bettendorf

A detached ADU (including one in a detached garage or other accessory structure) is allowed on any lot with a single-family house under Iowa's self-executing ADU law, Iowa Code 364.3(23), which requires every city to allow at least one ADU "either attached to or detached from" the house. Bettendorf's own code still says the ADU "must be attached to or within the residential structure" with a shared entrance door (City Code 11-11A-9(D)(8)(b), unchanged since Ord. 35-17 of 2017), but 364.3(23)(d) makes conflicting city text void, and city planning staff told the Planning and Zoning Commission on July 15, 2026 that the state law preempts local ADU regulation and a homeowner needs only a building permit meeting the bulk standards.

Attached and internal ADUs (basement, addition, conversion) are allowed with any single-family house. Bettendorf's code has permitted ADUs "in single-family homes" since the 2017 zoning rewrite (City Code 11-11A-9(D)(8)), but only through a Board of Adjustment special-use permit and with owner-occupancy, extra-parking, shared-entrance and design conditions; those conditions are void under Iowa Code 364.3(23)(b) to (d), so the state floor is the operative rule.

Iowa Code 364.3(23)(a)(2) sets the floor: an ADU may be up to 1,000 square feet or 50 percent of the house, whichever is larger, and SF 2369 (effective 7-1-2026) measures the house by gross living area excluding garages, decks, unheated porches and unfinished basements. Bettendorf's code still caps ADUs at a minimum of 400 and a maximum of 800 square feet (City Code 11-11A-9(D)(8)(f)), which is void; city staff applied the state formula in a September 2026 plat report (a 3,678 sq ft house qualifies for an 1,839 sq ft ADU). Height, setback and coverage rules apply only to the extent they apply to the house; the code's 15-foot, one-story limit for accessory buildings in required yards and its 1,000 sq ft or 75 percent detached-garage cap (11-11A-9(D)(7)(e), (g)) are stricter than the house's rules and cannot lawfully bind an ADU under 364.3(23)(b)(1).

No owner-occupancy requirement can be enforced. Bettendorf's code still says "The owner of the subject property must reside in one of the dwelling units on the property" (City Code 11-11A-9(D)(8)(c)), but Iowa Code 364.3(23)(b)(4) bars any requirement that the property owner be a resident, and 364.3(23)(d) voids conflicting city text. The city has not amended the paragraph.

Iowa Code 364.3(23)(b)(3) bars any parking beyond what a single-family house requires, or a fee in lieu. Bettendorf's code still requires "One off-street parking space, in addition to the parking requirement for the single-family home" (City Code 11-11A-9(D)(8)(e)), which is void; the house itself needs two spaces under the parking schedule in City Code 11-13-7.

An ADU needs only a building permit reviewed like a single-family house: Iowa Code 364.3(23)(c) requires approval "without discretionary review or hearing" on the house's timeline. Bettendorf's code still routes ADUs through a special-use permit ("The review and approval of an ADU application is by special-use permit", City Code 11-11A-9(D)(8)(a)), which the Board of Adjustment grants after a hearing under 11-15-9; that requirement is void. City staff confirmed at the July 15, 2026 Planning and Zoning Commission meeting that the city's role is reviewing the building permit for bulk-standard compliance.

An ADU may be rented long term; every rental unit in Bettendorf must be registered with the city each calendar year and pass periodic rental inspections (City Code Chapter 10-9, Rental Housing Registration and Inspection, rewritten by Ord. 01-25 of 1-7-2025), a general program lawful under Iowa Code 364.17 and 364.3(23)(b)(2). For short-term rentals (30 days or less), Iowa Code 414.1(1)(e) bars any city regulation or permit requirement specific to them, classifies them as a residential land use, and bars a licence or permit fee; Bettendorf's zoning table still lists "Bed and Breakfast/Short-term Rental" only as a special use in the C-3 and C-7 districts (City Code 11-4-5), which is preempted. Chapter 10-9 exempts transient lodging, so a nightly-rental ADU falls outside the rental registration. The local bar on dividing the house and ADU into separate condominium ownership (11-11A-9(D)(8)(d)) remains in the code, and staff state that an ADU cannot be sold separately from the house.