ADU rules in Ankeny

Ankeny's new Zoning Ordinance (Ord. 2268, effective October 1, 2026) defines an ADU as attached or detached and lists it as a Conditional use in the AG, RL-1, RL-2, RL-3, RM-1 and RM-2 districts, approved by the Development Services Director rather than a board. Section 196.02(6)(A) allows a single ADU on a lot with an existing single-family home, 'either attached or detached'. Iowa Code 364.3(23) independently requires the city to allow at least one ADU with any single-family residence, and the definition counts an ADU that is part of a detached garage as detached.

The same provisions cover attached and internal ADUs (basement apartments, additions, conversions): §196.02(6)(A)(1) says the unit 'may be either attached or detached', and the definition in §190.03(1) covers a unit 'either attached to or detached from the single-family residence'. Approval follows the Director-level conditional use route described under permit type.

Section 196.02(6)(A)(3) copies the state cap word for word: an ADU 'shall not exceed one thousand square feet or fifty percent of the size of the single-family residence, whichever is larger'. Ankeny sets no larger local cap. Note 13 to Table 190.20.05-2 has ADUs follow the principal-structure height and setback rules for the district (35 ft height in the RL and RM-1 districts), and the 10 percent lot-coverage cap on accessory structures in §191.07 expressly excludes ADUs. Since July 1, 2026 (SF 2369) unfinished basements are excluded from the ADU size calculation and 'size' means the house's gross living area excluding garages, decks and unheated porches; the city text does not yet say so, but the statute controls.

Neither the new Zoning Ordinance's ADU standards nor its definition require the owner to live on the property. Iowa Code 364.3(23)(b)(4) bars a city from requiring the property owner to be a resident or requiring a family, marital or employment relationship between the occupants. (The new code's owner-occupancy wording in §55.05 concerns chickens, not ADUs.)

Table 194.01 in the new code has no ADU row; a single-family detached dwelling needs 2 spaces 'per dwelling unit, plus 1 space per room rented out', and §194.01(1)(E) lets the Director set parking for unlisted uses by analogy. Iowa Code 364.3(23)(b)(3) forbids requiring 'additional parking beyond that required for a single family residence or payment of a fee in lieu', so any reading of Table 194.01 that would require spaces for the ADU itself is void.

Under the new code an ADU is a Conditional ('C') use, which §196.02(1) says is 'reviewed and approved by the Director or his/her designee', not by the Zoning Board of Adjustment; the city's October 2026 application form says review 'generally takes ten (10) working days', followed by the building permit. No hearing is held. However, §196.02(5) and (8) also apply general compatibility, property-value and comprehensive-plan findings and require a site plan and feasibility statement, which go beyond the state rule that an ADU meeting the statutory conditions be approved 'without discretionary review or hearing' on the single-family timeline; those parts are void as applied to ADUs under 364.3(23)(d).

The zoning text puts no rental limit on ADUs. Chapter 177 (Ankeny Housing Code, §102.12) requires every person who 'offers for rent a dwelling or portion(s) thereof' to apply for an inspection certificate, with regular inspections every two years for single-family and duplex rentals, and it applies to 'all rental dwellings ... including short-term rentals'; dwellings rented for 30 days or less are also subject to Iowa Code chapter 423A (hotel and motel tax). Iowa Code 414.1(1)(e) bars city regulation specific to short-term rentals and any STR licence or permit fee, while 364.3(23)(b)(2) bars ADU rental rules stricter than those statutes and chapter 562A. There is no separate-sale rule in the zoning text; the ADU sits on the same lot as the house.