Workshop Item - Elizabeth Showalter, Community Development Specialist
Title
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Discuss Regulations Related to Accessory Dwelling Units
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Background
Accessory dwelling units (ADUs) are dwelling units that are either attached or adjacent to a primary home and act as an accessory apartment with separate cooking and living spaces. ADUs are frequently referred to as mother-in-law units, but are not necessarily occupied by a relative. An ADU is different from a duplex in that standards are put in place to make the ADU clearly accessory to the primary home and there may be residency requirements to require either the home or ADU be owner occupied. ADUs can be built in a variety of ways including converting a walk out basement to a separate dwelling unit with separate entrance, building an apartment above an attached or detached garage, or building a detached structure in the back yard.
ADUs are commonly constructed to retrofit an existing home to accommodate multigenerational living or to create a rental unit for additional income. Recently, new home builders have started offering floor plans that include a separate living quarters marketed towards families looking to care for aging relatives or adult children with disabilities, accommodate adult children living at home, or to share mortgage payments between a parent and adult child. Lennar is currently offering their Next-Gen home in Lakeville and Rosemount and has previously offered it in Plymouth.
The Family Housing Fund published a policy memo promoting ADUs and listed the benefits to cities as:
1. Gentle increase to density in established neighborhoods.
2. Increasing assessed values of properties, adding to the tax base.
3. ADUs often have cheaper rent than other apartment units due to the smaller size.
4. Serving the increasing number of 1 and 2-person households.
5. Supporting stable homeownership by allowing owners to use rental income to pay mortgages, facilitating care of relatives, and providing an onsite downsizing option.
Potential reasons to not allow accessory dwelling units:
1. Can be seen as creating a duplex in an otherwise single-family home neighborhood.
2. If sufficient off-street parking is not provided, may result in an increase in on street parking.
3. Long term enforcement issues related to owner occupancy requirements.
Staff generally looks to a group of 10 peer cities that are similarly positioned in the metro when considering changes to the zoning ordinance. Of those cities, Brooklyn Park, Coon Rapids, Eden Prairie, Maple Grove and Woodbury do not allow accessory dwelling units.
Five of the peer cities allow for accessory dwelling units with varying processes and standards. The standards are outlined in the attached table. All of the cities require either the primary home or the ADU to be owner occupied, except for Lakeville, which requires the ADU to be accessible through an internal door between the units.
The Family Housing Fund policy memo encourages cities that want homeowners to construct ADUs to reduce regulatory barriers such as parking, owner-occupancy requirements, and design requirements. Alternatively, if the council wants to allow ADUs but not necessarily aim to have many built, those requirements can be in place to reduce the potential impact to the neighborhood. Standards to consider include:
1. Owner occupancy requirement for one of the two units (primary home or ADU).
2. Allow both attached and detached ADUs or only attached.
3. Require additional parking.
4. Require design to minimize the appearance of the second unit through door location.
5. Minimum lot size.
6. Limit to R-1 zoning district, or allow in any single-family district.
7. Require a conditional use permit or an administrative permit.
Staff Recommendation
Discuss whether to amend the zoning ordinance to allow accessory dwelling units, and if so, what standards to apply.
Attachment List
1. Peer City Chart
2. PowerPoint Slides