By Kirk Stelsel
Precast concrete has long been a staple building material in North America for everything from infrastructure products to architectural building materials. Beyond our shores, though, a thriving and innovative global precast concrete industry can lend ideas to designers and builders here at home.
In Stockholm, one of the newest additions to the skyline brings to mind an iconic structure in New York City. That’s because the wedge-shaped building is a sort of 21st-century reboot of the famous Flat Iron Building. While the Swedish version may share a name and some design cues, that’s where the similarities end.
The Swedish exterior has a distinctly modern feel that stands in stark contrast to the New York version, which is punctuated by lions’ heads, faces and terra cotta – a look that New York Magazine described as reminiscent of “an Italian Renaissance palazzo.” The modern facade of the Swedish version is wrapped in precast concrete panels, which added a number of attributes to the building. In addition to the exterior panels, the contractor used precast concrete hollow-core slabs and interior wall panels throughout the building.
With a short construction timeline, precast allowed Skanska, the building contractor, to increase efficiency and get the building to the rental market as quickly as possible. The facade panels were delivered to the site with preinstalled windows, eliminating the need for bulky, expensive scaffolding during construction. With the urban location, space for building material storage was also limited, making the just-in-time delivery of the precast elements an absolute necessity for the contractor. According to Skanska, the precast also provided the desired modern look and a high range of architectural and design options, and will offer reduced management and maintenance issues throughout the building’s life cycle.
Designed with sustainability in mind, the Swedish building earned a LEED Gold certification as well. The natural thermal mass of the precast panels allows for more efficient heating and cooling of the building, contributing to the eco-friendly assets of the building. The concrete also acts as a sound barrier between a rail depot bordering one side of the building and a residential area on the other.
A stunning example of how precast concrete can be used to define a design, not just support it, can be found at a recent expansion to the Tel Aviv Museum of Art. The structure was designed by Preston Scott Cohen, owner of Preston Scott Cohen Inc. in Cambridge, Mass. Cohen also serves as chair of the Department of Architecture and the Gerald M. McCue Professor of Architecture at the Harvard University Graduate School of Design.
The expansion includes an exterior shell made of 460 precast concrete panels. Each panel has four sides, but no two have the same shape or size. The panels, some as large as 30 ft on one edge, were cast using flexible-edge molds that were adjusted to the individual angles and dimensions. With so many different shapes, the need to drill holes in the casting table to bolt down the forms for pouring was eliminated by using powerful magnets the keep the sides in place.
At the 2014 Commonwealth Games, which will take place in Glasgow, precast concrete will be on full display. Decomo UK Ltd. was awarded a contract to provide 32,292 sq ft of architectural precast cladding for the Emirates Arena and the Sir Chris Hoy Velodrome.
The precast, featuring a black exposed-granite aggregate finish achieved through acid etching, creates a look that evokes the heritage of the region’s coal mining past. The 398 panels were used on the external facade of the two buildings and the interconnecting hub between them. Precast was specified for its durability and design flexibility, as well as inherent acoustic and thermal qualities.
In addition, SCC Ltd., also located in the United Kingdom, contributed precast for a 1,600-space parking garage. The garage utilizes SCC’s newly developed inverted frames, named IPCs (Integrate Precast Components), and its PFV (Precast Finished Voided) flooring system. Two semicircular ramps on the north end of the garage are also made of precast manufactured by SCC, and are thought to be the first of their type to be constructed in this way.
Kirk Stelsel is NPCA’s director of Communication.