On January 9, 2024, the Ames City Council adopted Ordinance 4516 allowing detached Accessory Dwelling Units (ADUs) as a secondary or accessory use in conjunction with single-family detached homes. The standards require an ADU to be a detached structure totally separate from the principal residence. The ADU cannot be attached to or located within the principal residence.

An ADU is allowed in any single-family zoning district that is not restricted by subdivision covenants. A property that already has more than one dwelling on the property cannot have an ADU. Having an ADU is subject to compliance with all City codes, including Zoning, Building, Utility, and Rental ordinances.

Yes. A building permit and related trade permits are required to construct an ADU. An ADU can be either premanufactured or constructed on site, but it will require a permanent foundation and cannot be a camper, trailer, or other mobile or temporary type of living unit.

When designing an ADU or selecting its location on a lot, you should be aware of different construction requirements based upon building and property line separations. Planning for a location that has at least 10 feet of separation from a building and 5 feet from a property line will have the fewest additional fire rated construction requirements. Fire separation requirements and rated construction will also apply to a garage with an ADU above the garage. Building Permit applications can be found on the Inspections Division website.

Only one dwelling on a property may be rented due to the owner residency requirement related to the construction of an ADU. Either the ADU or the primary residence may be rented subject to compliance with the Rental Code. See also Owner-Occupied Limitation and Rental Code Requirements.

No, the proposed changes to the code do not override subdivision covenants. HOAs may still opt to prohibit accessory dwelling units through their covenants. It is incumbent upon the property owner to verify whether covenants are in place and applicable to the property. The City of Ames does not review or enforce private covenants.

ADUs are limited to one bedroom. Occupancy is limited to no more than three adults. One bedroom is allowed as a separate room from the other living areas, or it can be incorporated into the common living area as a “studio” layout.

The City’s bedroom definition of the Zoning Ordinance will apply, which means that no additional rooms that are not a bathroom or kitchen and which exceed 70 square feet will be permitted within an ADU. This means that additional rooms labeled as offices, dens, or other will not be allowed. Only one bathroom and one kitchen will be permitted for an ADU.

The maximum size of an ADU is 900 square feet of gross floor area, measured around the exterior perimeter of the building and including all levels. However, the total square footage of all accessory buildings cannot exceed 25% of the rear yard and conformance to other site development standards. The rear yard is the area between the primary residence and the rear property line.

ADUs require one off-street parking space in addition to the two required for the principal residence for a total of three spaces. Parking must be on a paved surface that meets location and design of the Zoning Ordinance (Chapter 29 of the Ames Municipal Code). Although other spaces can be tandem or stacked, an ADU parking space cannot be in front off or behind another required parking space.

Prior to issuance of a building permit, a site plan showing compliant existing conditions or a driveway paving permit application must be approved. If an existing property has nonconforming unpaved parking, the site will be required to be brought into conformance with paved parking requirements.

The ADU standard is designed to create an additional living unit or living space that is accessory to an owner-occupied home. Either the primary dwelling or the ADU must be the primary residence of the property owner.

Not only does the owner residency requirement apply to registering a property as a rental property with the City, it also applies to any property owner seeking a building permit for construction of an ADU. The owner will need to verify residency status prior to the issuance of the building permit. The City will require that a “notice of limitations” describing the owner-occupancy requirement and rental property limitations be signed and recorded as a disclosure of limitations for future buyers of a property.

Owner-occupied means a “natural person” and must meet the definitions with the Ames Rental Code Chapter 13 for a primary residence and owner-occupied. A Trust or Corporation are example of entities that are not considered a “natural person” and are not eligible as property owners to construct an ADU or to register the property as rental for either the principal residence or the ADU.

A registered rental property will not be issued a building permit to construct an ADU, the property must be owner-occupied at the time the permit is issued.

When designing an ADU you may choose to either have a separate meter and utilities for the new building, or to connect it to existing services without having a separate meter. If a separate meter is installed the bill for the ADU can be separated from the primary home. If the utilities are shared, then only one bill is issued for the property.

The property owner will need to determine the feasibility of using existing services for a new ADU. If services are undersized, new or upgraded services may be required for the house and ADU. Alternatively, a wholly new service and meter may be beneficial depending on the location of the ADU on the property and the location of existing utilities.

No connection fee will be required for an ADU on a lot that has existing service. All other utility service and meter fees would apply.

Electric service is required to be provided underground to the new building.

All properties used for rental purposes must be registered with the City of Ames per the requirements of Ames Municipal Code Chapter 13 and meet all Rental Code standards. Only one of the two dwellings on a property may be rented, the other must be owner-occupied. Any principal residence or ADU used for rental purposes must have a valid Letter of Compliance (LOC). The LOC must be in place for the legal rental of either the ADU or the principal residence

If a property owner constructs an ADU but does not utilize either dwelling on the property for rental purposes, the property is not required to be registered or have a LOC for either dwelling.

Occupancy limitations will apply to the ADU and primary residence consistent with the standards of the Rental Code. The maximum occupancy for a one-bedroom dwelling unit is 3 adults.

Certain neighborhoods defined with the Rental Code have limitations on the number of bedrooms that may be utilized for purposes of determining occupancy. The list of Near Campus Neighborhoods can be found on the Rental Inspections website.

The maximum number of bedrooms for occupancy purposes is set based upon property conditions on January 1, 2018 within the defined near campus neighborhoods. Adding an ADU to a property will not increase the maximum number of occupants for a dwelling compared to the January 1, 2018 allowance.

A property owner may request a separate address for an ADU. If a property is registered as a rental property, an address will be required for each dwelling.

A duplex (two-family dwelling) is a building located on a single lot that includes two independent residences as a two-family building that are attached to each other and do not cross a property line.

The City Council is considering allowing duplexes that are “new construction“ only within all residential zoning districts. Under this proposal, a duplex could not be created by dividing an existing residence into two dwelling units or by constructing an addition to an existing residential structure to create two dwelling units. A new duplex could only be constructed on a residential lot that does not have an existing dwelling.

There are many existing duplexes in neighborhoods across Ames. In 2000, the City established limitation on new duplexes in many residential areas. Existing duplexes were classified as “Pre-Existing” which allows for the use to continue and for building to be altered or replaced. If the new standards are approved, existing duplexes would be subject to the new standards at the time they are altered or replaced.

No, the proposed changes to the code do not override subdivision covenants. HOAs may still opt to prohibit duplexes through their covenants. It is incumbent upon the property owner to verify whether covenants are in place and applicable to the property. The City of Ames does not review or enforce private covenants.

City Council directed staff to prepare design guidelines to help define the character of an existing neighborhoods and to incorporate certain features into the new construction of duplexes. Neighborhood “style” varies among neighborhoods depending upon the year of construction. The design standards focus on roof type, building orientation, and garages. The standards do not change the Historic District Overlay requirements or the Single-Family Conservation Overlay District requirements.

Duplexes require two off-street parking spaces per unit for a total of four spaces. Parking must be on a paved surface. Each duplex unit will be required to have at least one covered parking space within a garage. Standards for driveway size and parking locations will apply.

Prior to issuance of a building permit, a site plan or a driveway paving permit application must be approved. The required parking must meet all location and design requirements of the Zoning Ordinance (Chapter 29).

The proposed duplex regulations do not limit the number of bedrooms per dwelling. Occupancy is subject to standards of the Rental Code.

All properties used for rental purposes must be registered with the City of Ames per the requirements of Ames Municipal Code Chapter 13 and meet all Rental Code standards. The property must be registered if either one or both of the duplex dwelling units is used for rental purposes, and a Letter of Compliance (LOC) must be obtained for the duplex. If neither dwelling unit is rented, the property is not required to be registered as a rental property or to have a LOC.

The minimum lot size for new construction of a two-family dwelling is 10,000 sq. ft. in Near Campus Neighborhoods. Information on Near Campus Neighborhoods can be found on the Rental Inspections website.

The Rental Code limits increasing the number of bedrooms for occupancy calculations for dwellings that existed on January 1, 2018. This does not change even if a building is demolished and a new one constructed.