Executives at The Davis Companies wanted to renovate an existing building to create an expanded office/laboratory facility that could meet a variety of current and future space needs. Their goal was to strip an existing one-story, 140,000-square-foot building to its structural framing, add 47,139 square feet in four stories of space onto that base, and then clad the entire structure to provide a creative, contemporary look.
The cladding material had to be economical while providing a flexible design that could interact easily and aesthetically with curtain wall, according to John Sullivan, director of architecture at SGA, the architect of record on the project. The cladding would be used on three sides of the new five-story building, with curtain wall covering the entry façade. Economics were critical to ensure the building’s Class A spaces remained competitive in a lower rental area of the Cambridge, Mass., neighborhood.
The designers evaluated precast concrete panels and called in Strescon Ltd. to help plan an efficient design, maximizing its advantages for a complex design. “We were brought in during the design phases to consult with the architect and construction manager and troubleshoot façade concepts using precast concrete,” explains Jerry Grassby, business development manager at Strescon.
The key challenge resulted from the staggered placement of windows and the mixture of three finishes on narrow rectangular panels making up the larger panels. “The ability of the precast panels to have a skin appearing to be random patterns of textures while actually maintaining a rigid set of repetitive and interchangeable panels allows for a façade of flexibility and nuance at a low cost,” explains Matt McCreary, SGA designer.
A key focus for Strescon was working through each connection to the frame with the various panels and determining the casting sequence. “We had to plan out how the panels would connect with the different window placements in the panels and work with the steel fabricator to create the proper connections in the right locations,” Grassby explains. “We also had to determine in what order to cast panels, as the variations in textures meant there were more pieces than would be expected. There were a lot of column covers and spandrels.”
The existing first-floor structure also presented a challenge, as the steel columns were encased in concrete and their structural durability had to be determined. “The intricacies of these base panels were more complex than for upper floors,” Grassby says.
Strescon worked through a variety of issues in the bid documents prior to them being released. “Strescon was very helpful in working with the color selection, levels of sandblasting, ribbing texture, and coordination in our efforts to reduce the number of panel types,” says Jim Highum, SGA project manager. Once the documents were released, Strescon’s bid was accepted.
“Every aspect, from working with the local Strescon sales representative early on to working with the project manager at the plant, was very seamless,” says Eric Svahn, SGA project architect. “Touring the plant to see panel forms in production and some finished products was very helpful in assuring quality control.”
Panels Erected Vertically
The panels were erected in a vertical format, dictated by the inherited structural grid of the existing building, McCreary explains. Each panel features patterns of long, narrow rectangles with one of three finishes. Using a baseline of slightly warmer earth tones, the panels are distinguished by the light and heavy levels of sandblasting to reveal different amounts of aggregate offset by the third finish featuring tight rows of reveals. The combination creates patterns of textures and colors, with no two areas, including column covers between windows, using the same sequence.
With help from the early planning, the panel erection, accomplished with a tower crane, moved smoothly. It was completed in February 2018. The building is planned for occupancy in 2019.