Story at a glance:

  • Railyard Flats in South Dakota is said to be the state’s first modern mass timber building.
  • Dowel-laminated timber, or DLT, was used on this all-new construction.
  • DLT uses wood dowels to join laminations instead of glue, nails, or screws.

Mass timber is growing in popularity as a sustainable, economical, and attractive material for low- and mid-rise mixed-use buildings. Beyond its contribution to efficient construction, mass timber provides architectural distinction for developers seeking high-quality design (and peak lease rates) in up-and-coming urban locales.

Like many mid-size metro districts, Sioux Falls, South Dakota has undergone a major growth spurt in the last decade. The state’s most populous city is one of the fastest growing in the US, currently estimated at 1.8% growth annually. Sioux Falls’ Eastbank neighborhood, in particular, was forged in the early 2000s to help spur downtown expansion.

More than a decade later, a vacated railroad switchyard in the area has catalyzed the next phase of development, including the state’s first modern mass timber building, Railyard Flats.

A Hybrid Story

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Photo by 605 Creative Coop

Boutique real estate developer Pendar Properties maintains a small and focused portfolio of unique properties in Sioux Falls. The firm is solely focused on creating a vibrant downtown, emphasizing walkable, mixed-use communities with distinctive design. In pursuit of this vision, Railyard Flats is proving to be their crown jewel.

The four-story, 83,000-square-foot mixed-use project is one of the first new developments in the burgeoning Eastbank locale, offering 41 loft-style apartments atop ground-floor retail and two stories of office space. Walkability, art, and community are featured amenities, as well as a shared rooftop deck and fitness center.

One of the property’s most notable characteristics, however, is its use of mass timber. Railyard Flats is the first in South Dakota to use the next-generation building material, and it’s the first mass timber undertaking for Pendar Properties and local design firm CO-OP Architecture. Their decision to use structural mass timber and a hybrid light-frame system was driven by a number of factors, including sustainability and ease of construction. Most of all, the team knew wood would set their project apart.

“We wanted to build a community and tell a story,” says Anne Haber, partner at Pendar Properties. “CO-OP understood our desire for quality, sustainable construction, and our push to try new things.”

“The more we discovered about mass timber—from the aesthetics to the environmental qualities—the more we realized this was the direction we wanted to go,” Haber says.

Modern, Historic Appeal

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Photo by 605 Creative Coop

Initiating new construction in one of Sioux Falls’ original railyards proved to be a delicate venture. The area was once an important center of rail commerce, and the vacant site required a high-caliber, modern design that could simultaneously pay homage to the local railroad culture. With these considerations top of mind, the resulting design showcases wood’s structural and aesthetic capacities—creating a distinguishing, contemporary aesthetic while also maintaining the industrial appeal valued by locals.

“The mass timber really gives the space a warmth like nothing else. Plus it’s an excellent choice for someone who is environmentally conscious and appreciates incredible structure and design standards,” Haber says.

Railyard Flats is 100% new construction but is often mistaken as a renovation project. “The biggest compliment we receive is when a first-time visitor finds familiarity with the building,” says Thomas Hurlbert, principal architect at CO-OP. “There’s a beauty here that surprises people.”

All Wood, All Good

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Photo by 605 Creative Coop

Wood plays heavily throughout Railyard Flats’ hybrid structural design, with visual-grade glulam beams and columns, and mass timber decking that is exposed as a ceiling, topped with a thick sound mat and concrete for an added sound barrier. The walls are light-frame construction with an exterior brick facade. This design provides stability, durability, and warmth, tapping into the material’s biophilic properties to create inviting spaces within the building.

As pioneers of mass timber construction in South Dakota, CO-OP sought expertise from design/engineer/build powerhouse, StructureCraft. The Canadian firm specializes in timber and hybrid-timber construction, translating architectural vision into engineered structures.

For Railyard Flats, StructureCraft recommended an engineered wood system less commonly seen in the US—dowel-laminated timber (DLT). DLT uses wood dowels to join laminations instead of glue, nails, or screws. It is gaining traction in America for its ease of use with computer-controlled (CNC) machinery as well as its all-wood composition. Because all the wood grain runs in one direction, DLT is structurally efficient and best suited for flooring and roofing applications.

Prefabricated 5.5-inch DLT panels were ideal for Railyard Flat’s long horizontal spans, and the thinner material proved cheaper than a cross-laminated timber (CLT) alternative. DLT also helped designers improve the project’s visual appeal of the exposed ceiling through the addition of a fineline kerf profile to the exposed board edges. “What we love about timber is that the exposed structure becomes a unique part of the architectural expression,” says Gerald Epp Jr., BD Engineer at StructureCraft.

“We wanted to offer something unique leveraging the value, the ambiance and the aesthetic of exposed wood. It’s also sustainable and extremely efficient from an engineering perspective,” Epp says.

Beyond the White Box

Railyard Flats opened in summer 2021, garnering peak lease rates and 100% residential occupancy. CO-OP and Pendar Properties are both commercial tenants in the new space, joined by local cocktail bar Highball. In addition to walkable access to shopping, restaurants, and bars, occupants of Railyard Flats are in close proximity to outdoor amenities including adjoining green spaces and a private bike trail.

“This is not your typical white box apartment,” Haber says. “We have pushed the rates to the highest in Sioux Falls. Our location, amenities and design are opening up a whole new idea of what it means to live downtown.”

Find out more about Railyard Flats by watching this online course from WoodWorks or taking a virtual tour.

Project Credits

Name: Railyard Flats
Location: Sioux Falls, SD
Completion: Summer 2021
Size: 83,000 square feet
Architect: CO-OP
Client: Pendar Properties
Material: Dowel-Laminated Timber (DLT)
Application: Mixed-use residential/commercial
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