Accessory Dwelling Units: Meeting the needs of a growing community

March 24th, 2023
By Allie Martinsen

"There is no one-size-fits-all solution to the challenges facing our cities or to the housing crisis, but the two issues need to be considered together." – Architect Richard Rogers  

Across the nation – and especially across the Upstate – the current housing stock fails to meet the needs of all residents. To help remedy this issue, accessory dwelling units (ADUs) have been championed as a strategy to diversify housing stock and better meet varied housing needs. During a time when the Upstate is struggling to meet the demand for housing, ADUs may be part of the solution.  

ADUs, also called “in-law suites” or “granny flats,” are secondary, smaller dwelling units located on the same lot as a primary dwelling unit. ADUs can look very different depending on the home, but all ADUs are designed to blend seamlessly into the neighborhood. In many cases, you may not even know an ADU is there. Examples of ADUs include a basement conversion, a garage conversion, or a detached unit (like a backyard cottage).  

ADUs are uniquely positioned to meet a variety of housing needs. ADUs offer an additional living space for multigenerational families, such as young adults returning home or older family members wanting to age in place (a trend that increased during the pandemic). ADUs can also offer an additional source of income for homeowners, while filling a gap in affordable housing.  

From a conservation perspective, ADUs have a small environmental footprint. Instead of building out and contributing to sprawl, ADUs take advantage of the space on residential lots that already exists. In doing so, ADUs can utilize existing infrastructure and save more resources.  

It’s worth noting that not all homeowners have met ADUs with excitement. Some residents have expressed concern that ADUs may change the distinct character or feel of a neighborhood. Others have shared trepidation that a rise in neighborhood density could result in increased demands for parking and school enrollment.  

Luckily, strong policies can resolve these concerns at the outset. For example, ADUs are often limited to one structure and a maximum square footage per lot, which results in minimal increased need for parking. Design standards can also ensure that ADUs are set back from the primary residence and designed to match the feel of the neighborhood and style of the primary residence. Since ADUs predominantly serve young adults, extended family members, and small households, it is unlikely that ADUs will significantly impact school enrollment. Lastly, many ordinances create restrictions on short-term rentals, so residents don’t have to worry about Airbnbs infiltrating their neighborhood.  

Are ADUs going to start springing up all over your neighborhood anytime soon? Probably not. According to Alexandria’s principal planner, Sam Shelby, “This isn’t going to change your neighborhood overnight or even in a generation.”  Even if ADUs are permitted in your zoning district, it is highly unlikely that every neighbor will decide to pay for the high cost of construction and maintenance needed to build an ADU (or decide to take on the task of becoming a landlord).  

For example, in St. Paul, MN - a city with a population of over 300,000 residents - only 12 ADUs were built by late 2021 (after passing an ordinance to allow ADUs in 2018). In Boise, Idaho – a city with a population of over 235,000 residents (and more than triple the size of Greenville) – only 20 permits were issued in 2019.  

At the end of the day, it’s important to remember that ADUs are just another tool in the toolbox. Although ADUs fill a critical gap in housing needs, they are not a cure all strategy. That said, they are a good place to start.   

Allie Martinsen is Land Policy Manager for Upstate Forever. You can email her at

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