Although the addition to the St. Louis Art Museum will increase the museum’s space by 30 percent, it is meant to be unobtrusive; its black concrete facade helps it virtually disappear at night, except for its glass front. Courtesy of the St. Louis Art Museum
A 200,000 sq ft addition to the St. Louis Art Museum maximizes the use of daylight without endangering the priceless artwork within.
April 16, 2013—Over the past century the Saint Louis Art Museum, which was designed by Cass Gilbert as the Palace of Fine Arts for the world’s fair held in St. Louis in 1904, has become a revered symbol of the city. So when the time came to add space to the structure, planners strove to create a modern addition that would take full advantage of the museum’s assets—its turn-of-the-century design, its priceless art, and its exposure to plentiful sunlight.
“The design approach was to get as much natural daylight filtered from above [as possible] without direct daylight touching the paintings,” says Roger McFarland, AIA, a group vice president of the international architecture, engineering, and planning firm HOK, which worked on the nearly 10-year effort to design and build the museum’s expansion. HOK collaborated with David Chipperfield Architects, of London, which was the principal design firm; Seattle-based Magnusson Klemencic Associates, the civil and structural engineers; and London-based Arup, which served as the mechanical, electrical, and plumbing designers.
The museum’s new, 200,000 sq ft wing will be illuminated by a glass ceiling encompassing nearly 40,000 sq ft and supported by a matrix of concrete beams. The design allows sunlight to be reflected into the galleries rather than transmitted directly, preserving the integrity of the artwork.
The $162-million expansion increases the museum’s space by more than 30 percent yet remains within the confines of the museum’s former parking lot; in this way the project required no green space. The hope is that when visitors enter the new wing, which is to open in late June, they will never feel far removed from Forest Park, the large urban park that surrounds the museum. A new, 300-car parking garage was deliberately located belowground and out of sight.
To avoid detracting from the original building, planners chose a simple design that relies on concrete as a means of structural support and as a finishing material inside the galleries and on the facade. “It was a very deliberate and difficult design to absolutely minimize the building elements and to accentuate the art,” McFarland explains.
The matrix of concrete beams that supports the addition’s skylight-style glass ceiling creates more than 700 rectangular coffers, each 5 by 10 ft, says Greg Briggs, P.E., S.E., M.ASCE, a principal of Magnusson Klemencic. Steel posts rising from the 1 ft wide, 4 ft high concrete beams support the glass panels, which have been given a special coating to prevent the artwork from being damaged by ultraviolet light.
A matrix of concrete beams supports the addition’s skylight-style
glass ceiling, creating more than 700 rectangular coffers into which
the glass panels are set. David Chipperfield Architects
Each skylight has a horizontal blind that will automatically open 15 minutes before the museum opens for the day and close 15 minutes after closing time to minimize unnecessary exposure to sunlight. During the summer the blinds will shield the galleries from the sun for five hours a day, and on Mondays, when the museum is closed, the blinds will remain closed.
When visitors are in the gallery, daylight will be diffused by what McFarland calls “one-of-a kind, custom-made light spreaders.” These 3 by 8 ft plastic-coated filters are 9 in. thick and are suspended within the rectangular spaces created by the concrete beams.
The design team tested the light spreaders at four different levels of translucency and provided the museum with three extra types so that the level of light can be altered for different exhibitions; works of art on paper, sketches, and watercolors, for example, are more sensitive to sunlight than are paintings on canvas, McFarland explains.
Track lighting is attached to the perimeter of each light-diffusing panel to enhance lighting on darker days, and speakers, motion detectors, and sprinklers are also attached to the ceiling units.
The mechanical air return grills needed for the galleries are overhead and out of view. Also hidden from view are concrete-filled steel tubes that run up through the 1 ft thick gallery walls to support the matrix concrete beams above. Concrete shear walls along the perimeter of the building provide lateral support for the new structure.
Since so much of the interior concrete would be visible, the design called for the concrete to be cast in place to ensure smooth joints and corners. The designers also experimented with the concrete mixture, varying the amount of titanium dioxide to maximize the concrete’s reflectivity. The concrete inside accentuates sunshine, McFarland says, and makes the galleries look deceptively large.
The exterior’s black facade makes the expansion almost invisible at night. To create a smooth, modern appearance, designers used concrete panels—some as large as 22 by 42 ft and weighing 80,000 lb—and minimized the visibility of the borders between them.
Workers cast the concrete panels on-site and then ground them down three-fourths of an inch to create a smooth surface and reveal the local aggregates that were included in the mixture so that the addition would gracefully complement the existing museum.
“They wanted a very highly polished, very clean-looking finish on the facade,” Briggs says, adding that to accomplish that, workers “cast bigger slabs on-site and lifted them into place and created a more monolithic appearance.”