A new study published by the Greater Ohio Policy Center found that if Columbus eases some red tape to build accessory dwelling units, the move could potentially save homebuilders thousands of dollars.
Columbus city code says an ADU must connect to city sewer lines independently from the main home on a property. The Greater Ohio Policy Center argues in its study that letting an ADU's sewer line be routed through the main home would potentially save tens of thousands in construction costs by not tearing up driveways or other parts of a property.
Casey Terry, a research manager with the policy center, told WOSU the idea behind this could work for many, but not all properties in Columbus. She pointed out some homes in Columbus have a sewer line in the rear of the house in alleyways rather than on the street in front of a house.
"Installing sewer infrastructure in general, you're building huge trenches and it's a lot of work and disruption to the property," Terry said.
Terry, and the study, say the idea behind this policy proposal lends to a wider push to provide "gentle density" to cities like Columbus struggling with a housing crisis. Columbus recently relaxed some laws for the small backyard homes last year in an effort to ease tensions on the housing market.
"We knew that there was an interest at the city in developing ADUs. So we thought this is a good opportunity to see how that could be made easier," Terry said.
In a statement, Columbus City Council Member Christopher Wyche, the chair of the council's public utilities and sustainability committee, said the council will take the suggestion under consideration.
“Columbus has a well-documented housing crisis,” Wyche said. “Council has been supportive of utilizing ADUs as one of many strategies to address our housing shortage. We know about the challenges related to connecting ADUs to water and sewer infrastructure and have been working with (Columbus Water and Power) to identify ways to reduce these costs, including potentially subsidizing these connections. I appreciate the work of the Greater Ohio Policy Center for identifying potential code changes for us to take into consideration.”
Officials with several Columbus city departments, including Columbus Water and Power, didn't respond to requests for comment.
The study explains that on lots where the primary house fronts a street with a main sewer, an ADU must either have its own lateral sewer line separate from the home or it could connect with a common service line that could be built on the property that connects both the home and the ADU to the street sewer line.
The study found a third configuration routing the ADU's sewer line through the main home isn't allowable under Columbus city code, but is in several other cities.
The policy center found this third, currently illegal, configuration would cost roughly $5,000 to implement compared to costs at the high end ranging from $20,000 to $60,000 for the configurations that Columbus allows.
The study said it did speak with Columbus city officials who cited concerns with the idea. These include that:
- With a lack of individual sewer laterals for each unit, one of the units could create a sewer backup for the other.
- Selling or conveying the property with this configuration could create problems at the time of sale if the sewer lines for the two units are not separated. Specifically, a future owner may want to sell the main house and ADU separately and potentially would not be able to because of the shared sewer line.
The policy center found in peer cities that allow this configuration, accept that any backup issues could be addressed by snaking and jet spraying and that having the same property owner for the ADU and primary dwelling unit helps facilitate this maintenance.
The experts the study spoke to said if the sewers are tied together in the manner illustrated in this scenario, splitting the sewer lines might not be possible, but market value of the property wouldn't be diminished.
The study points out that parts of the state of Ohio's plumbing code also plays a role, but Terry said some Ohio cities, like Cleveland, have laws on the books that make it easier to connect ADUs to the sewer lines through a main home on a property.
Terry said Columbus isn't necessarily behind, but rather it is tracking with other cities trying to make changes to allow ADUs more easily.
"I'd say (Columbus is) about on par. Cincinnati made a similar zoning change several years ago to allow for ADUs, so that is significant," Terry said.
The policy center also studied requirements in Austin, Texas, Ann Arbor, Portland, Oregon and Boston.
