A 70-story, folded, creased and curved stainless-steel curtain wall on an 867-ft-tall apartment building has been called "Gehry only on the outside," as if the building is a fake Frank. It's true that, when it opens next year, New York City's tallest residential tower won't be an internationally acclaimed cultural icon, as is the architect's now-12-year-old Guggenheim Museum Bilbao in Spain. The 76-story high-rise is not as colorful, whimsical and structurally innovative as the nearly decade-old Experience Music Project rock 'n' roll museum in Seattle. The new tower is not as description-defying inside and out as the six-year-old Walt Disney Concert Hall in Los Angeles.

But that building was torturous to build: There were 10,000-plus requests for information (RFIs), and it was $174 million over budget and the subject of a dispute that ended in a $17.8-million settlement.

Draping Lower Manhattan's Beekman Tower, Frank Gehry's creases may only be skin-deep, but the depth of the building team's accomplishment-producing a budget-driven, speculative apartment tower with the signature of the "king of swoopy" all over it-is not superficial.

The job, topped out and clad to the 51st floor, is under budget and on schedule, discounting a three-month work hiatus related to the Great Recession, says the local developer, Forest City Ratner Cos. FCRC says there are no claims to date and only 100-plus RFIs on the entire job, including the seven-faced, 319,000- sq-ft drape on all but the south face-hands down, the architect's most ambitious facade ever.

This project is "Frank Gehry demystified," says Joseph A. Rechichi, an FCRC senior vice president.

Bruce Ratner, FCRC's chairman, had a Gehry "sculpitecture" in mind from day one. But he also wanted an economical and constructible Gehry, with minimal process pain. Initially, "we were concerned about [the curtain wall's] constructibility, and long-term use," Rechichi says.

The facade's success relied on several strategies. One was the development of a traditional unitized curtain-wall system for the wall's air-and-water barrier, with an outer rain screen for the wild shapes. Unitized systems are unusual for residential towers, especially rental ones. "For the size and scale of the project," however, it had to have a unitized system, says John Bowers, Gehry's project manager.

Unlike a stick-built system with costly field labor, a unitized system is shop-fabricated. Workers can install finished units quickly, without expensive staging.

On Beekman Tower, a floor plate can be completely enclosed in four to five consecutive working days, says Bowers. "The greatest advantage of a unitized wall system is in the schedule," he says.

"Our ability to divorce the wall from the balance of the building was huge," adds FCRC's Rechichi.

A key move on FCRC's part was to engage the curtain-wall supplier early under a design-assist contract. Another key factor was the use of sophisticated digital tools, including building information modeling (BIM) and computer-numerically controlled (CNC) cutting tools. Automation has "enabled me to bring buildings of architectural quality to fruition," says the Los Angeles-based Gehry.

FCRC also used veterans of Gehry's past projects for the facade and the reinforced-concrete superstructure. Curtain-wall supplier Permasteelisa North America (PNA) worked on the Disney concert hall and Manhattan's 10-story Interactive Corp. headquarters-Gehry's only other unitized curtain wall. Concrete contractor Sorbara Construction Corp., Lynbrook, N.Y., built Interactive.

The 1.1-million-sq-ft Beekman is a mixed-use development with a sculptural tower-a fat "T" in plan-that will contain 903 market-rate units. The tower sits on a 100-ft-tall, six-story rectilinear podium, clad in masonry. The podium has a public school, the city's first on private land, as well as an ambulatory care center for New York Downtown Hospital, which owns the land.

FCRC declines to reveal contract values and construction costs, except to say it closed on $680 million in bonds for the tower in March 2008. This total includes $204 million from the New York Liberty Bond Program, issued by the New York Housing Development Corp. The National Electrical Benefit Fund, FCRC's equity partner, also provided a loan.

Gehry's starting point for the facade's design was the residential bay window, which lets "you step outside the [flat] facade, as if you were walking on air," he says.

Gehry wanted a sense of movement-enter the folds, creases and curves connecting the pointed bay windows. "I've been playing with this issue of folds for years," he says. He finds fabric folds primitive and comforting. "They humanize the building," he says. For the Beekman facade, "I told my guys I wanted Bernini folds," which have a harder edge, "not Michelangelo folds," which are softer.

Gehry Architects New York PC started conceptual design in late 2003. From 2004-05, the architect explored 50 or so schemes, applying the geometry to the wall surface using 1?16-in.-scale physical models. In late 2005, when the scheme had been honed to stainless steel with punched windows, Gehry started building 1?8-in. models. The architect also digitized the surface to create a BIM.

Also in 2005, FCRC issued a request for proposals to three curtain-wall suppliers for a design-assist contract based on Gehry's scope and parameters. "We liked [PNA's unitized] design and engineering, and they met our budget," says Rechichi. Also, PNA was the only bidder familiar with CATIA-the sophisticated 3D model Gehry had used on Bilbao, Disney, EMP and other projects.

During the design-assist phase, PNA, with Gehry, developed a set of rules to turn the wall's free-form shapes into something that could be mass-produced. The goal was to minimize the expense of a double curvature and maximize more economic, "rule-able" surfaces.

The phase, which included developing the entire panelization scheme and keeping the curvature within the budget, took more than two years. "You can't do a job like this without design-assist," says Michael Budd, executive vice president in PNA's Mendota, Minn., office. Strong collaboration is needed to get to the required level of definition, he adds.