Corrugated Cardboard Creates 'Corduroy' Concrete

John Hill
7. Mai 2020
Photo courtesy of Post-Office Architectes
Project: 30 Warren, 2020
Location: Tribeca, New York City
Client: Cape Advisors
Architect: Post-Office Architectes
Executive Architect: HTO Architects
Facade Consultant: Front, Inc
Facade Manufacturer: TAKTL / Schuco Rainscreen Solutions
System: Custom TAKTL system
Products: TAKTL Ultra High Performance Concrete (UHPC) in RAL 8019 color / Schuco window system
Facade Installation: GGL Enterprises
30 Warren Street with Herzog & de Meuron's 56 Leonard Street in the distance (Visualization: Post-Office Architectes)

Thirty Warren Street was designed by Post-Office Architectes, the firm of David Fagart, Line Fontana, and François Leininger that is based in Paris and New York. Leininger heads the NYC office, and he designed 30 Warren as a dark, asymmetrical mass punctuated by large windows. The setbacks create terraces on the upper levels, accompanied by projecting balconies that provide much-desired outdoor space for some of the 23 condo units. 

This rendering shows the long west facade on Church Street and the glass curtain wall on the narrow north facade. (Visualization: Post-Office Architectes)

The building is located a few blocks north of the World Trade Center site and one block east of City Hall. The narrow L-shaped lot spans from Warren Street on the south to Chambers Street on the north, with its main facade along Church Street. Most of the exterior is covered in the precast concrete panels, though the setback north facade is all-glass, giving residents on that end of the building expansive views of Herzog & de Meuron's 56 Leonard Street, the tallest building in Tribeca.

This close-up view shows the glass facade on the north but also, more importantly, the desired "ever-changing" effect of the precast concrete panels. (Visualization: Post-Office Architectes)

Although it sits across the street from one of Tribeca's historic districts and therefore did not require the approval of the Landmarks Preservation Commission, the approach to the exterior facade makes 30 Warren a neighbor respectful to its context. An all-glass facade would have been too dramatic a departure for such a location. "We wanted to tell the story of a building," Leininger said, "that would appear undoubtedly contemporary, yet would speak to some of the qualities of historical Tribeca, and that would look domestic." A synthesis was achieve by using precast concrete: "We imagined a facade that would appear strong yet light, fragile yet durable, anchored yet floating."

Scaffolding came down recently to expose the textured precast facade to the neighborhood. (Photo courtesy of Post-Office Architectes)

More than 900 panels — some as large as 11' x 3'6" — cover the building, with over 70 molds required for the different sizes and interactions with the four types of windows. Consistent across the precast panels is the texture, which was achieved, Leininger said, "by casting concrete over strips of corrugated cardboard laid at a 45° angle." The goal was "an ever-changing facade," dependent upon lighting conditions, time of day, and position of the observer. To Leininger, "the panels look at times crafty and mineral, and at times soft and light like corduroy."

The angled lines of the corrugated formwork are apparent the closer one gets. (Photo courtesy of Post-Office Architectes)

The 3/4" thick panels are made from TAKTL Ultra High Performance Concrete and were installed as a rainscreen. Post-Office exploited the system to introduce ambiguity: "We exposed these thin panel edges everywhere, to create the idea of a veil, floating over the building, about 6" away from the glass. A concrete veil, light yet strong."

Lines perpendicular to the cords are visible, the meeting of different rolls of corrugated cardboard during fabrication. (Photo courtesy of Post-Office Architectes)

The precast panels were mounted with concealed anchors, meaning the "corduroy" texture is not marred by any exposed fasteners. The 1" joints between panels, which align with the center of windows rather than their edges, is another important detail. As Leininger explained, "a 'web' of 1-1/2" wide aluminum channels, painted black, [run] along every joint on the back of the panels… These channels make the joints look like deep grooves while concealing the insulation behind the rain screen."

Drawing: Post-Office Architectes
Drawing: Post-Office Architectes

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