The bold design of the C&E Flats redevelopment project transformed a 90-year-old garage into a luxury apartment complex with 119 living units. Plans called for gutting the existing building, adding tenant amenities, retail and parking space in the middle of the gutted structure while keeping the historic exterior walls intact, and then building five levels of apartments on top. To meet this exacting challenge, project architect/engineer BKV Group capitalized on the flexibility of precast concrete components and utilized specially designed precast hollowcore planks and other precast components from County Materials Corp.
The innovative plan to redevelop the 1927 General Motors Truck Company garage-type structure into luxury apartments created several challenges. First, the building’s interior would have to be demolished while the outer shell was kept in place. Keeping the façade in place also would limit access to the construction site because the new structure would be built within the existing footprint. Lastly, the first floor needed to have large open spaces to house several amenities, including the parking garage, which itself required a fire-resistant material.
The vacant old GM building was made up of two large garages and open bays. The use of precast hollowcore plank allowed this multi-level space to house amenities for tenants including street-front lounges, clubrooms, a fitness center, a restaurant, a brewery, retail space, and indoor parking. The new C&E Flats’ 119 apartment units were built on top of these additions.
Precast sized to fit
C&E Flats is the final stage of the C&E Community development located in the University-Raymond Commercial Historic District in Saint Paul, Minnesota. The first phase was completed in 2012 with the opening of C&E Lofts, an open loft-style apartment complex built inside the 100-year-old Chittenden and Eastman Building. During the renovation of C&E Lofts, a neighboring building became vacant. Exeter Group bought the newly vacant space to facilitate construction of the eco-friendly C&E Lofts project.
Exeter Group wanted to add another substantial apartment complex to the former General Motors Truck Building complex. However, the building’s structure would not allow a renovation similar to the one done at the Lofts project. The single-story, warehouse-style building was not an ideal layout for constructing apartments. Because the building itself had no historic designation, complete demolition was an option. However, renovations or changes still needed approval from the Saint Paul Historic Preservation Commission. Exeter Group doubted the commission would allow a complete demolition. In addition, Exeter group wanted to preserve the exterior brick because it fit the historic neighborhood.
BKV Group found a solution in hollowcore plank manufactured by County Materials. County became part of the process every step of the way, from designing, manufacturing, and building. Early in the planning stages County Materials’ drafting professionals assisted in designing and sizing hollowcore to fit the project’s needs. Hollowcore’s ability to span longer distances with minimal support structures made it an obvious choice for the daunting goals of this project.
Custom formed hollowcore
Construction began with the demolition of the building’s interior. During this phase, the exterior façade was supported by metal beams to prevent any damage or collapse of the walls. After the demolition, a design specialist from County Materials visited the site and surveyed the walls to determine lengths for each hollowcore plank. After surveying the site, the design specialist knew the erection process would take careful planning because of the building’s unique shape, including a 120-degree corner.
Each piece of hollowcore plank was then custom-formed in County Materials’ controlled manufacturing facility to fit the layout of the existing building. County Materials sub contracted Zachman Precast, Inc. to erect the hollowcore. A single crane was deployed to the site to erect columns, beams, and hollowcore for the building’s first level. This phase included more than 380 planks of hollowcore and solid slabs, 50 of which were precisely cut with an angled end to fit the building’s shape. Extra deep beams and specially designed planks provided a sturdy system on which to install a roof-top swimming pool. The designers used the large open area under the pool for additional parking spots. After this phase, a tower crane sat on top of the just-erected hollowcore structure in order to erect the additional five stories of residential living space.
In total, County Materials provided 113 deliveries of hollowcore plank. After erecting the precast concrete structure, County Materials and Zachman Precast signed the site back over to Frana Companies, the general contractor. Hollowcore maximized the construction process for crews arriving back onsite because of its compatibility with other building materials and it provided an immediate working deck to continue construction. The hollowcore erection took place late fall 2016 and was completed in an impressive two and a half weeks. Frana Construction continued construction for the next year. C&E Flats opened its doors to residents in August 2017.