Planners, elected officials and developers agree that Knoxville needs to allow higher density development to accommodate the anticipated increase in population over the next two decades. The current housing crunch has made the situation acute.

The report suggests allowing duplexes, triplexes and other small multi-family housing options in areas within walking distance of commercial hubs.

Zoning laws that have been in place since the 1940s that have favored detached single-family houses have made achieving higher density outside downtown difficult to achieve. Basically, new housing in Knoxville can be single-family dwellings or large apartment complexes, with little available in between.

That “missing middle housing” is the focus of a recently released report on possible solutions from Opticos Design, a California-based firm that specializes in walkable urban design. The City of Knoxville, Knoxville-Knox County Planning and the Knoxville Area Association of Realtors jointly commissioned the study.

Missing middle housing types include duplexes, triplexes, fourplexes, townhouses, cottage courts (multiple detached houses with a shared courtyard), and larger multiplexes of up to 18 units. Individual housing units have smaller footprints than typical detached single-family houses and less off-street parking is required.

Developing more such units would give homebuyers more options, including more affordable price points, the report says. The study also looks at barriers to building small multi-family houses in Knoxville.

“It’s a reflection of the need for more housing at all prices,” Knoxville Chief Policy Officer Erin Gill said in a recent interview. “We need to look at housing in a broad sense.”

Knoxville is projected to add more than 14,000 additional residents by 2040, which, given the average household size of 2.18 people, means around 6,600 new housing units will be needed to accommodate the growth.

According to the report, 56 percent of millennials and 46 percent of baby boomers want to live in more walkable neighborhoods, with 59 percent of millennials and 27 percent of baby boomers looking for missing middle housing.

“This is the first step to help us refine our understanding of the local landscape,” Gill said. 

Knoxville officials should consider changing the city’s zoning ordinance to encourage duplexes, triplexes and other multi-unit developments for infill housing near walkable commercial nodes, Opticos Designs recommends.

Hancen Sale, government affairs and policy director for the Knoxville Area Association of Realtors, said adopting policies and regulations that encourage building medium-density housing would transform the local market.

“It’s a big part of the future of the city of Knoxville,” he said. “Missing middle housing is a way to increase housing in a way that doesn’t stand out from existing communities.”

Knoxville has some examples of the type of small multi-family housing recommended by the report in older neighborhoods surrounding downtown, but little has been built in the past 75 years. 

The report emphasizes that such housing creates medium-density areas without appearing to do so because projects are built on a similar scale to the surrounding single-family houses. 

The study focuses on four of Knoxville’s residential zones — RN-2, RN-3, RN-4 and RN-5. In general, the lower the RN-number, the lower the density and the greater restrictions on housing types. 

Sale said about 80 percent of Knoxville’s residential property is zoned RN-1 or RN-2. Density limits effectively preclude duplexes and other missing middle housing types in low-density R-1 zones, which weren’t included in the study, and R-2 zones, which were.

Sale said more density in an area makes nearby businesses more viable. And viable businesses can attract more residents.

“Walkability is more than sidewalks,” he said. “It’s about having something to walk to. That’s when it works well.”

The Opticos Design report recommends changing the city’s zoning code to allow small multi-family residences, but only within a 10-minute walking distance of commercial centers. That excludes many neighborhoods established since World War II.

The study identifies 23 such “walkable centers” throughout the city. They are mixed-use, pedestrian-oriented areas with a blend of restaurants, retail and service businesses. Examples include Bearden, Burlington, Old Sevier and the area around Central Street and Broadway in North Knoxville. 

Areas that could become walkable centers with infrastructure investments include the intersections of Clinton Highway and Merchant Drive, Western Avenue and Middlebrook Pike, and North Broadway and Tazewell Pike. Other locations along the Kingston Pike, Broadway, Western Avenue and Clinton Highway corridors could become walkable centers as well.

Opticos Design doesn’t recommend a complete zoning overhaul for the four residential zones considered in the study; instead, the firm recommends changes to their requirements. The study suggests eliminating density requirements, setting minimum lot widths instead of minimum lot areas, reducing setbacks, limiting parking to one space per unit, and regulating a building’s height and footprint instead of its lot coverage.

The study says that missing middle housing types and standards could be adopted in targeted areas as a new zoning designation or an overlay that only applies to identified walkable neighborhoods. Because the city’s walkable centers are surrounded by existing neighborhoods, projects to fill the missing middle gap would almost exclusively be infill housing.

Sale said the local demand for small multi-family housing is difficult to determine because there is little of it in Knoxville and new units can’t be built under the current zoning code. Developers, he said, don’t propose such projects because the zoning code essentially bars them.

“There would be a huge demand for it if we had more of it,” Sale said. “Realistically, the zoning piece has to come first.” 

No action has been taken yet on the report’s recommendations. Knoxville overhauled its zoning ordinance in 2019 through the Recode Knoxville process, and Gill said any effort to revise the code to allow more small multi-family housing would go through an extensive public review.

“The breadth and depth of this report is enough to move forward with a workshop with Council,” she said.“It gave us a lot to work with to come up with an approach that we’re comfortable with and the public is comfortable with.”