The American Folk Art Museum, New York, New York, is a seven-story building that displays the museum’s permanent collection and changing exhibits as well. The goals of the project were to provide open spaces with natural light on a constrained site and to create an image for a small museum in the shadow of the larger Museum of Modern Art. The museum’s second through fifth floors are devoted to gallery space and are capped by a skylight above an atrium. The atrium allows natural light to filter into the galleries and public spaces. Art is integrated into the stairwells and walls of the museum by way of a series of niches throughout the building. The building also incorporates museum offices, classroom facilities, auditorium, library and archive, gift shop and small coffee bar. The unique bronze-paneled façade alludes to the folk art inside and establishes the museum’s independence from the surrounding buildings.
The overall budget of the project was $18.4 million. An allocation of $4.1 million was set aside for the structural portion of the project, which eventually came in under budget at $3.9 million. Due to the use of exposed architectural concrete, money initially designated for exterior architectural finishes was transferred into the budget for concrete work.
The unique and challenging nature of the museum became apparent before the building rose from the ground. Adjacent to the museum, the subway tunnel and subway ventilation room beneath 53rd Street demanded a variety of accommodations. Heavily loaded adjacent footings could not bear on the sub-grade rock within the influence line of the subway tunnels. To bypass this problem, a cantilevered foundation bearing on steel-encased caissons was utilized. The caissons are located seven feet north of the subway tunnel and are embedded into the rock beneath the influence lines.
The design process of the building itself posed a variety of challenges in accommodating the architect’s vision and the structural integrity of the building. For instance, the 40-foot-wide site left little space for circulation and light. Therefore, the bold decision to pierce each floor with an atrium was balanced against the desire to maximize exhibit space and floor-to-ceiling heights. Specific requirements and site conditions pushed the engineering team to apply innovative solutions to achieve these defined goals.
Initially, various structural materials were evaluated for their suitability. The clear-spanning 40-foot width of the gallery with a 30-foot span around the atrium made a steel frame appear to be the best solution. However, this would have increased the depth of the structural system, particularly when married with the mechanical system. Fortunately, the architect was willing to leave the concrete exposed, thus eliminating the need for the space-consuming fireproofing and finish materials that the steel would have required. Formwork was simplified by designing the floors as 16-inch-thick flat plates rather than beams with soffits.
The exposed concrete adapted well as a finished building material. Walls and soffits (where needed) were sandblasted to provide a dull, matte finish, and floors were terrazzo-ground to expose the concrete’s aggregates. Concrete’s sound- and vibration-damping qualities was another advantage.
The construction of the two interior stairs employed concrete’s ability to be sculpted. The rear stair is a series of cantilevers extending from the fifth floor down to the first floor mezzanine. Each run of stairs has a torsion-reinforced, 8-inch-deep-by-two-foot-wide spine that runs from the floor to the landing, across the landing, and up to the floor above. A 4-inch-thick edge follows the steps of the stair and extends out to the perimeter of each landing, completing the appearance of a minimized structure.
Another concrete stair extends through the atrium. It is hung from the edges of the atrium opening by concrete sidewalls. Construction joint locations were selected to hide the construction-tell-tales of the stair. Approximately eight-feet apart, the walls extend from above the fourth floor to below the third floor. Each wall extends over the edges of the floor slabs, and the construction joints between floors in the wall slabs are hidden in reveals. Stair treads span the eight feet from wall to wall and were cast into wall keys to hide their joints. With all of the construction joints hidden, the stair appears to have been magically inserted into the concrete building.
A concrete hanger at the building rear resolved a quandary of competing program and aesthetic requirements.. Achieving an open main entry hall was complicated by the architect’s desire to open a vertical slot along the back façade of the building. The rear façade s;slot virtually eliminated a spandrel beam from the third through fifth floors, and a transfer girder located at the second floor would have obstructed the entry hall.
With the roof as the only suitable location for the transfer girder, the hanger was required to support the floors below. It was determined that maintaining a reinforced concrete system and leaving the rear of the building shored until the roof was cast and cured would be more cost effective than using a structural steel frame.
Furthermore, the reinforcing in the concrete hanger was designed for both strain and strength. Reinforcing just for strength would not eliminate visible cracks in the hanger under full load. By increasing the amount of steel reinforcement, the strain in the hanger under full load is kept below the strain at which visible cracking occurs in concrete, thus eliminating visible cracks.
The bronze facade of the American Folk Art Museum is designed to make a strong but subtle statement of independence from the Museum of Modern Art. The façade is sculptural in form and folded into faceted planes of bronze and glass. The three major planes of the façade are composed of white-bronze panels that were “spill-cast” against the foundry’s concrete floor. The bronze panels and planes catch the glow of the sun as it rises and sets, east and west along 53rd Street.
Spill casting produced panels with a mottled surface and exposed cold seams, but also panels that were inconsistent and which defied specification. Representative test panels were cast and tested to produce design parameters that were then applied to the façade. Ultimately, the panels were welded onto steel frames to provide additional stiffness and connection points. Originally, the idea was to provide another steel frame on the face of the building to receive the panels; however, a cost-savings was realized by building a backup wall with heavy 6-inchstuds and plywood sheathing.
Planes of curtain wall make a recessed reveal along each side of and beneath the panels to lighten the façade and make the planes of bronze appear to float above the entrance. Though the 16-inch slab is sufficient to carry the weight of the floor and façade across the 40-foot southern face of the building, early analysis showed that the relative live load deflection and the creep of the concrete would drive the size of the joints between panels up to 2 inches. Unwilling to accept joints of this size in the façade, the design team instead installed a “post” in the middle of the front façade. A single, true column was initially proposed, but its size was considered an intrusion to the appearance of the floating façade, particularly since it would be the only concrete element among surfaces of metal. As a result, three smaller stainless steel pipes, which don’t stand out awkwardly and which keep the façade panels square and true, were installed. The super-structure and foundations were designed to perform with or without the steel pipes so that they could be left exposed.
By developing innovative solutions, the design team was able to produce a building that realized the architect’s vision and was economical. With attention to program, efficiency, economy, and site constraints, the design team provided effective solutions to the unique and varied challenges involved in the museum’s design. The American Museum of Folk Art demonstrates engineering excellence coupled with the advantages offered by architectural exposed concrete.
The American Folk Art Museum was selected "Best New Building in the World for 2001," and in October 2002, the building was awarded the prestigious Brendan Gill Prize by the Municipal Art Society of New York. It also won the 2003 award for engineering excellence from the New York Association of Consulting Engineers (NYACE).
Primary Consultant and Architect:
Tod Williams Billie Tsien & Associates Architects, New York, New York
Seamus Henchy & Associates, New York, New York
Pavarini Construction, Stamford, Connecticut
Severud Associates, New York, New York
Reginald Hough, FAIA, Rhinebeck, New York