Glazing services to architects: Custom Work

Design and construction of building envelopes have become such complex processes that support services to architects—ranging from product selection and specification to energy ratings—have become integral to the work of every glass and glazing professional. To this end, even fabricators and contract glaziers in relatively small markets add to their staffs draftspeople and salespeople experienced in working with architects. It's not always the sheer cost of these tailored services at issue—property owners ultimately pay—but their availability and quality as well. A handful of fabricators and contractors sometimes change their business models to highlight the expertise of their project-development teams. Look for a few business models in the following articles.

Curtain-wall consultant 

Although Cesar Pelli & Associates’ mixed-use development at 731 Lexington Ave. in New York City was not a design-build project, the design and construction processes, completed in 2005, bore marked similarities to design-build. The fabricator, contract glazier and a curtain-wall consultant—the latter an agent of the owner—all had hands in creating the building envelope, says Rafael Pelli, partner in charge of Pelli’s New York City office.

William F. Logan, an architect by training and a principal at Israel Berger & Associates of New York City, served as curtain-wall consultant.

Such experts “form a bridge, having the knowledge of the criteria early in the design stage to sit at a table and inform our design decisions,” Pelli says. “They have knowledge of design possibilities grounded in technical parameters. They have worked on other projects and tried to solve similar issues. They make sure our drawings correctly represent what we want. In production, curtain-wall consultants help represent us to fabricators. They also represent owners in quality control, field verification and testing. They make sure things get installed properly and provide a critical glue.”

Then, “we worked out coordination and technical issues with the fabricator, who contributed expertise and made revisions based on how the company could achieve our intentions,” Pelli says. It involved close teamwork with extensive shop drawings and resubmittals based on regular meetings with all the parties.

Presenting the options
Starting at schematic design stage, “we do a lot of listening to see where the architect wants to go,” Logan says. Pelli wanted this project to be transparent, he wanted different parts of the complex—retail area, base podium and tower—to stand out from one another and have articulation at each level to create shadows. Logan helped protect those elements through development, contract-document, testing and construction phases.

“We don’t do calculations, but we identify performance criteria that the contractor’s engineers use to design the system,” he says. “This takes the form of thermal and structural performance measures, meeting building codes, constructability and getting the look that the architect was after.”

Logan had a hand in selecting the contractors: “Probably half a dozen people could have built this project,” he says. “We interviewed four or five potential contractors along the way and got some feedback.” A team of Enclos Corp. from Eagan, Minn., and Baker Metal Products Inc. of Dallas did the engineering, design, fabrication and erected the curtain wall. Other companies worked on the retail spaces.

When selecting fabricators and contract glaziers, Logan looks for the ability to perform the following:
•  Engineering
•  Prepare outstanding shop drawings and contract documents that include thorough specifications
•  Do mock-ups and thoroughly test them to failure
•  Translate energy-performance requirements set by the mechanical engineers into curtain-wall systems
•  Excellent project management.

Factory finish
Pelli’s Lexington Avenue project presented Logan with a number of challenges: Initially, Logan says, Pelli had created an elliptical courtyard that would have resulted in creating a building with no two pieces of glass alike. Instead, they began working with segments of perfect circles that helped bring the cost of construction down.  Similarly, designers studied point-fixed and cable-net schemes before settling on their installation method. For a good part of the Lexington Avenue project, Pelli says, the glass was set in a custom unitized curtain-wall system in Texas and trucked to the city.

In addition to the curtain-wall folks, a representative from the general contractor “was always at the table.” Calendars and transportation issues—including times the trucks would come over the bridges and hoist schedules—were top of mind as much as quality issues.

Engineers from the architect’s and structural engineer’s offices, as well as the contract glazier and fabricator, participated in wind-tunnel tests necessary to do the load calculations and final designs. “Most curtain-wall fabricators will do their own final engineering, with some preliminary work done by a structural engineer,” Pelli reflects.
Hence, the ability to do world-class drawings and engineering has become essential, as has “having the kind of engineers internal to [your] organization who know how to work with architects. We get the best results when we can sit at the table with the fabricator and work things out,” Pelli says.

731 Lexington Ave., New York City
Owner: Vornado Realty Trust, New York City
Architects: Cesar Pelli & Associates, New York City; SLCE, New York City
General contractor: Bovis, New York City
Curtain-wall fabricators: Baker Metal Products Inc., Dallas; Enclos Corp., Eagan, Minn.  
Structural engineers: Thornton-Tomasetti Engineers, New York City
Curtain-wall consultant: Israel Berger & Associates, New York City
Glass: More than 17 kinds, most from Viracon of Owatonna, Minn., and Oldcastle Glass of Santa Monica, Calif., including clear glass insulating units with low-emissivity coating on the No. 2 surface; shadow-box panels containing clear glass with a low-e coating on No. 2 surface and painted metal back panels. First-floor glass includes laminated reeded glass, laminated translucent glass and low-iron glass; tower lantern, laminated glass, clear glass with a white translucent interlayer.