ORDINANCE NO. 4596 AN ORDINANCE TO AMEND THE MUNICIPAL CODE OF THE CITY OF AMES, IOWA, BY AMENDING SECTIONS 29.409 AND 29.1502 THEREOF, FOR THE PURPOSE OF AMENDING ACCESSORY DWELLING UNIT (ADU) STANDARDS, REPEALING ANY AND ALL ORDINANCES OR PARTS OF ORDINANCES IN CONFLICT TO THE EXTENT OF SUCH CONFLICT; AND ESTABLISHING AN EFFECTIVE DATE. BE IT ENACTED, by the City Council for the City of Ames, Iowa, that: Section One. The Municipal Code of the City of Ames, Iowa shall be and the same is hereby amended by amending Sections 29.409 and 29.1502 as follows: "Sec. 29.409. ACCESSORY DWELLING UNIT (ADU) STANDARDS. An ADU is a newly constructed additional residential dwelling unit located on the same lot as a single-family residence as defined by state law. This includes properties with a single-family or two-family dwelling defined within the Zoning Ordinance. (1) Where Permitted. (a) An ADU is permitted on any lot: (i) with only a single-family residence and (ii) that is within a zoning district that allows for single-family residence as a principal use. * * * (c) An ADU proposed for a lot within a local historic district or on a locally designated property shall be regulated to the extent that the City or Historic Preservation Commission determine that the proposed ADU would be incongruous with the historical, architectural, archaeological, or cultural aspects of the area, and enters into official records the reasons for such determination. * * * (2) Independent Dwelling Unit. (a) Location. An ADU: (i) May be attached to the single-family residence. (ii) May be detached from the single-family residence in a free-standing structure. (iii) May be located within a converted, existing accessory structure, so long as the structure complies with all ADU requirements, including setbacks. (iv) May not be established within an existing single-family residence. * * * (3) Development Requirements. * * * (b) Setbacks. (i) Where side setbacks are based on building height, the single-family residence and the detached ADU shall individually have minimum setbacks based on their respective heights. (ii) Setbacks for an attached ADU shall be the same as the single-family residence to which it is attached. * * * (4) Size Limitations and Bedrooms. (a) The ADU must not exceed 1,000 square feet or 50% of the size of the single-family residence, whichever is larger. (i) Size means the gross living area of the primary dwelling unit excluding garages, decks, and unheated porches. (ii) The size calculation of an accessory dwelling unit shall exclude unfinished basements. It may therefore be impermissible to finish and complete an unfinished basement of an ADU if finishing this space causes the ADU to exceed the size limitation set in Sec. 29.409(4)(a). * * * Sec. 29.1502 Site Development Plan Review (7) Alternative Design Review. * * * (d) Ineligible Standards. The following standards in Chapter 29 of the Municipal Code are not eligible: * * * (vii) Dwelling Design Standards of 29.409 and 29.410, with the exception of ADU standards for side and rear setbacks and lot coverage. Section Two. All ordinances, or parts of ordinances, in conflict herewith are hereby repealed to the extent of such conflict, if any. Section Three. This ordinance shall be in full force and effect from and after its passage and publication as required by law. Passed this 23 day of June, 2026 Renee Hall, City Clerk John A. Haila, Mayor June 26 2026 LIOW0545577