The Ames City Planning and Zoning Commission recommended that City Council adopt zoning text amendments to align local accessory dwelling unit (ADU) rules with a state law that takes effect July 1.

Staff summarized the state legislation, saying it allows ADUs where single‑family homes are permitted and caps ADU size at 1,000 square feet or 50% of the primary residence. Staff recommended measuring size using the city’s existing gross floor area definition to provide clarity on how the 50% limit will be calculated. Staff also recommended removing local restrictions that required owner occupancy and additional on‑site parking for ADUs, and clarifying that ADUs are allowed on properties with duplexes where state law permits.

Staff noted the city’s rental‑code occupancy limits for near‑campus neighborhoods remain in effect and will continue to limit total occupancy even if an ADU is added. The city attorney advised that occupancy limits apply equally to single‑family properties and ADU cases where rental rules apply.

Commissioners discussed setbacks and staff explained that prior code allowed reduced rear setbacks for single‑story ADUs; because the state law prohibits differential height or setback rules for ADUs versus single‑family homes, staff proposed eliminating the reduced rear‑yard exception and bringing ADU setbacks in line with the primary dwelling standards.

A commissioner moved to recommend Alternative 1, adopting the proposed ordinance language to implement the state changes and to use the city’s gross floor area for measuring ADU size. The motion was seconded and passed by voice vote. The recommendation will proceed to City Council.