Wide Angle

Lower East Side Tower Rises Above Tight Zoning Specs

Tight zoning constraints inspire the team behind Blue to design and build a one-of-a-kind tower on Manhattan's Lower East Side.

by Alex Padalka

The distinctive cantilevered and pixilated appearance of Blue, a new 16-story, 32-unit condominium building set to open in October at 103-105 Norfolk Street on Manhattan's Lower East Side, was a complicated response to big development hurdles.

Several factors contributed to decisions that created the project's unusual profile, including three different zoning regulations, sightline restrictions, air rights that extend only above an adjacent low-rise discount goods store, and the need to maximize the use of a small lot, said John Carson, co-developer with Angelo Cosentini in a partnership that has built 11 other buildings in New York.

The neighborhood has seen its share of bold architectural styles from the Rivington Hotel a few blocks north, partially designed by Pritzker-prize winner Zaha Hadid of London, to the Switch building designed by New York's nArchitects right next door to Blue. Those angular, sleek, and modern designs have helped to turn what once was a neighborhood of tenement housing for immigrants into a mixed zone of older urban quarters and luxury enclaves.

Zoning regulations have also influenced design decisions on such new projects by forcing developers to buy air rights from their neighbors in order to build taller structures.

The zoning issues merged with Carson and Cosentini's desire to create a standout structure, said Bernard Tschumi, design architect on the $17 million Blue, which is the first residential project for his firm.

"We wanted something distinctive and architecturally beautiful, and at the same time [we had to] work with extremely constraining zoning regulations," he added. "We were able to combine the two and turn them into our advantage, like in judo - taking the strength of your opponent."

A central element of the 182-ft.-tall design is the use of cantilevering to extend beyond a 50 by 100 ft. site footprint. On the south side, the building juts out above the store with a cantilevered public >> terrace on the second floor. The building continues to cantilever outward from the fourth floor to the 12th floor, but the top two floors on that side are set back.

Meanwhile, the east side angles inward for the last five floors, and the west side is missing a rectangular chunk from the top two floors in another setback required to fit within the zoning constraints.

The design team has maximized buildable space "to the inch," Carson said. The units are on the market on a range from $775,000 to $3.5 million, and were 70 percent sold out in May.

If designing the maximum allowable structure was a challenge, building it was no easier as the project team got to work last summer. To support the cantilevered sections - which extend 22 ft. at their widest point - the team drove 67 supporting piles, Carson said.

Furthermore, because the 22-ft. cantilevered section over the store to the south would cause tremendous stress on the supporting walls underneath, the team decided to use one-story-deep cantilever beams and cast-in-place concrete walls. The team got to the 22 ft. in part by sloping the columns 13 in. further away from the elevator core on each floor as the cantilevered section stretches outward.

In addressing the cantilevered sections, the structural design also tackled wind load and seismic load issues, said Elie Gottlieb of New York's Thornton Tomasetti Group, the structural engineer on the project.

"We had to take into account that [the building] has a tendency to lean to the south, so we had to balance that weight on the north side," he added. "We did it by making sure that the walls extend all the way back to the elevator core, and by working with the architects on the shape and form of the building, coordinating very early in the process."

All the cantilevering and the setbacks meant that almost no floor plate is alike, not to mention the columns, said Igor Kirtchakov, president of IBK Enterprises, the concrete subcontractor on the project.

"It's much more interesting, challenging, and complicated than conventional, traditional construction," he added. "It was a challenge to design the supports and shoring for the cantilevered floors, since they extended above an existing building."

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Kirtchakov said IBK always embeds poured-in safety straps into the bottom of each floor plate to allow workers to hook up their harnesses. Such a safety feature was especially reassuring on a construction site where the ceiling extends more than a foot beyond the bottom slab on several floors.

In addition, concrete pouring for the sloped south side required extra precision to position "P-clips" to hold the curtain wall of 3- by 10-ft. multi-colored panels.

The complexity of the design and the unorthodox components of the project meant that the structural engineer had to work more closely than usual with the architects. Meanwhile, the concrete crews stuck around to help the curtain wall installers.

The entire process was streamlined through weekly meetings that the developers organized between all team members that Tschumi called a "community of the mind."

The choice of the largely blue pixilated glass panels stemmed from the need to design a façade for a building on which almost every supporting column was in a different alignment - all while using floor-to-ceiling windows as often as possible, Tschumi said.

It was also a question of aesthetics.

"I hate the kind of context in which people imitate the brick façade next door," Tschumi said. "It's not just visual: I liked the mosaic of the old and new, the mix of generations on the Lower East Side."

Key Players

Owner, Developer, Construction Manager: On the Level Enterprises, New York (Angelo Cosentini and John Carson)

Design Architect: Bernard Tschumi Architects, New York

Project Architect: SLCE Architects, New York

Concrete Superstructure: IBK Enterprises, Brooklyn

M-E-P, FP Engineer: Ettinger Engineering Associates, New York

Structural Engineer: Thornton-Tomasetti Group, New York

Curtain Wall Consultant: Israel Berger & Associates, New York