The Block & Kuhl Department Store, designed by the renowned architectural firm of Holabird and Roche, was constructed in downtown Peoria, Ill., in 1904. Known locally as The Big White Store for its gleaming white terra-cotta cladding and soaring 7-story height, the building was the first steel-framed structure in the city.
During the past 120 years, various additions were made to the complex, including the Art Deco 2-story, brick masonry A&P Market Building in 1932, one of the earliest contemporary grocery stores in America, and the Annex in 1949, a stylistically separate retail building with a modernist aesthetic. While in operation, the complex served as an anchor point for a thriving downtown. However, as shoppers migrated to suburban malls in the mid-century, the building was subdivided and eventually completely vacated—a story that is echoed across many Midwestern towns.
Saved from demolition after sitting vacant for several years, the complex recently underwent an adaptive reuse program and is now office space for the non-profit health-care provider, the Order of Saint Francis (OSF) HealthCare Ministry.
Established in 1876 when a group of nuns began caring for local patients, free of charge, OSF has a long history and strong ties to the Peoria area, and it is currently the city’s largest employer. This project provided a unique opportunity to consolidate OSF’s administrative teams while revitalizing downtown Peoria. As part of the project, the buildings were identified as contributing structures within the Downtown Peoria National Historic District, have been recognized on the National Register of Historic Places and received a prestigious 2023 Richard H. Driehaus Foundation National Preservation Award.
To effectively upgrade the buildings, the design team of Dewberry, JLK Architects and Thornton Tomasetti was challenged with evaluating the original terra cotta that remained while improving the exterior envelope performance. Additionally, the original materials were gone from the spandrel areas—ripped out during prior renovations—resulting in the need for replication of the 120-year-old designs with modern technologies.
ORIGINAL TERRA-COTTA CLADDING
Prior to the recent renovation, the only original terra-cotta cladding that remained on the former department store consisted of the original column covers and elaborate cornice, crowning the building. Close-hand reviews and exploratory openings determined that the remaining terra cotta was in remarkably good condition for a building that had been vacant for years. There were only localized areas of cracking and spalling.
Terra cotta often suffers from deterioration related to embedded support steel. In an exterior wall system, small cracks allow water to enter, which can cause issues during freeze-thaw cycles (accumulated water freezes within the system and causes damage to the materials) or the corrosion of embedded, unprotected steel elements, such as shelf angles, ties or rebar. As steel corrodes, it expands in volume, resulting in pressure on the surrounding masonry materials system and eventual spalling. This is especially apparent on historic buildings, which did not have the high-performance coatings or flashing systems that exist today.
For this building, the present-day condition of the terra cotta benefited from its original design, which included a waterproof glaze and tight mortar joints—only 1/8- to 1/4-inch wide in most areas. Additionally, the structural steel was held back from the building face to provide protection from the elements.
As part of the renovation project, the team evaluated the terra-cotta construction to determine if the addition of insulation and/or vapor barriers was feasible without detriment to the historic building fabric. Materials testing was conducted and incorporated into a hygrothermal (WUFI) model to understand the current, as-built performance, as well as to study several conceptual retrofit options, including the addition of closed-cell spray foam or mineral wool. The evaluation revealed that the team’s instinct on the existing performance was correct: The exterior glaze on the terra cotta served as an effective weather barrier. Any additional vapor barriers applied to the inside face of the wall could potentially trap moisture. Furthermore, additional insulation would prevent drying by the heating system because the terra-cotta would be isolated from the interior, undergoing more frequent freeze-thaw cycles. At the conclusion of the study, the team determined the best course of action would be to eliminate additional insulation at the areas of original terra cotta from the design scope and instead focus on improving the roof and secondary elevations clad with durable face brick.
REPLICA MATERIALS
Additional thermal improvements were made possible with the inclusion of replica windows and spandrel panels constructed with modern materials. Because the original spandrel panels and windows were removed decades ago, the team hunted down the building drawings at the Chicago History Museum, which boasts a large Holabird and Roche collection. The collection showed the original construction at spandrel panels to consist of terra-cotta cladding supported by backup brick masonry and steel shelf angles and window lintels. The team also found some early versions of “shop drawings”, which demonstrated the architect’s original design intent shown as a detail section with the terra-cotta fabricator’s notes and slight revisions overlaid by hand.
These original drawings provided the foundation for the appearance of the replica materials. However, the design team understood that the lead time and sequencing for the project, which also required new aluminum windows, would be critical to its success. Rebuilding each spandrel panel with hand-set masonry would have added time to the schedule and complicated sequencing. Additionally, a solution that matched the historic construction did not allow for much space to add thermal insulation. As such, the team turned to glass-fiber reinforced concrete (GFRC) panels as a solution. GFRC panels are a composite material that is lighter weight and thinner than traditional terra cotta.
The spandrel design ultimately relies on a grouted concrete masonry unit (CMU) knee wall. The large windows at each floor bear on the knee walls; the design intended to provide flexibility, allowing either the GFRC panel or the window to be installed first at the contractor’s discretion. The design also allowed the building to become fully enclosed early on, which enabled interior finishing work to begin during critical winter months.
The knee wall functions as a cavity wall, consisting of the grouted CMU, closed-cell spray-foam insulation, an air cavity and the GFRC panel. Support anchors for the panel were installed in the grouted cells of the CMU wall prior to installation of insulation, providing continuity to the system, which also functions as the vapor barrier.
Careful study was necessary where the new windows and spandrel panels met the original columns clad with terra cotta. Heat-transfer analysis was conducted using THERM to ensure the anchors for the new windows did not introduce areas of thermal bridging, which could result in cold spots and related condensation issues. Because of the historic nature of the project, many mockups and samples were necessary to ensure the color, sheen and joint pattern of the GFRC matched the surrounding original terra cotta.
The use of modern materials and analysis has returned The Big White Store to its early splendor while maintaining its 120-year-old theme of innovation. Careful study and evaluation have allowed the building’s original elements to function as they have historically performed while new construction methods have provided better thermal comfort and performance to building occupants. As the OSF Health- Care headquarters, the building once again serves as a focal point in downtown Peoria.
RETROFIT TEAM
ARCHITECT: Dewberry
PRESERVATION CONSULTANT: JLK Architects
STRUCTURAL ENGINEER AND BUILDING ENVELOPE CONSULTANT: Thornton Tomasetti
GENERAL CONTRACTOR: POINTCORE Construction
MASONRY RESTORATION CONTRACTOR: Otto Baum Company Inc.
MATERIALS
GLASS-FIBER REINFORCED CONCRETE SPANDREL PANELS: DeVinci Precast
ALUMINUM WINDOWS: Wausau Window and Wall Systems
CLOSED-CELL SPRAY-FOAM INSULATION: PSI Preferred Solutions Inc.