BENSON BUILDING ADAPTIVE REUSE

Stone Group Architects is proud to have led the award-winning adaptive reuse of the historic Warnock Building in downtown Sioux City—an Excellence in Construction Award recipient for projects over $20 million. Originally constructed in 1921 as an auto assembly and dealership facility, the reinforced concrete structure was later partitioned into commercial offices during the 1930s. After decades of use, the building was vacated in 2018 due to elevator mechanical failures, leaving a significant historic asset in need of thoughtful restoration and reinvention.

As architects specializing in historic renovation and adaptive reuse in Sioux City, IA, our team partnered with a local developer to transform the six-story structure into a vibrant mixed-use development. The ground floor remains commercial, while floors two through six were converted into 83 luxury apartment units known as the Benson Lofts. The basement now provides underground tenant parking, and new amenities include a club room, tenant fitness area, and a rooftop patio thoughtfully integrated between the two existing penthouses.

Preserving the building’s architectural integrity was central to the design. Exterior restoration included repairing and reinstating damaged marble and terra cotta ornamentation, restoring brick detailing, and rebuilding the parapet and cornice. Original prism glass elements were preserved, and remaining historic windows were restored, with all replacements carefully matched using historically accurate replica windows and storefront systems. The roof was fully replaced with a new membrane system, and specialty thickened pavers were engineered to accommodate modern railing connections without compromising the historic envelope.

One of the most significant design opportunities stemmed from the building’s robust reinforced concrete column and floor system. Leveraging this structural capacity, our team introduced a central lightwell that brings natural light deep into the building’s interior and dramatically improving livability for units that would otherwise lack exterior exposure. This intervention balanced preservation with innovation, enhancing both architectural performance and tenant experience.

Today, the Warnock Building stands as a premier example of historic renovation in Sioux City, IA, preserving its early 20th-century character while delivering modern residential functionality. Through strategic problem-solving, detailed restoration, and intentional design, our team at Stone Group Architects successfully revitalized a vacant, century-old historic structure into a thriving downtown destination.