Manhattan West is one of the largest and most complex developments currently underway in New York City. The project, first conceived in the 1990s, is a seven million-square-foot, mixed-use development above active railroad tracks where minimal buildable land existed.
It is an entirely new neighborhood, bound by Ninth and Tenth Avenues and West 31st and West 33rd Streets, that SOM master-planned as part of a larger revitalization of Manhattan’s Far West Side. The master plan calls for six buildings – four designed by SOM – that will bring retail, offices, residences, and hospitality to a previously underdeveloped district.
Public space is the heart of the master plan. The buildings are organized around a series of distinct plazas – designed in collaboration with landscape architect James Corner Field Operations – that were enabled by the engineering of a 2.6-acre platform that covers the rail tracks, which connect to Penn Station. The development’s central plaza is lined with a combined 225,000 square feet of retail to activate a vibrant new gathering space for residents, office workers, and travelers from the station. From Ninth Avenue, the public space will form a series of urban corridors along West 31st and West 33rd Streets, and the central plaza will pick up where West 32nd Street – which terminates at Penn Station on Seventh Avenue – left off.
Together, these urban connections will help form a new destination at Manhattan West, and create a gateway from Penn Station and Moynihan Train Hall to Hudson Yards. When complete, Manhattan West will be a 24-7 neighborhood with both hospitality and residential components in the 21-story Pendry Hotel and the 62-story Eugene. The boutique hotel – which is currently under construction and comprises 164 guest rooms and suites – is characterized by an elegant, softly curved facade that makes a distinctive addition to the complex.
Overall Concept of The Pendry
The Pendry was planned to be one of the smaller buildings in Manhattan West. Because the building would not compete for attention in the skyline, SOM focused on designing the building to be experienced from up close, through its silhouette and careful detailing. For the facade, the hotel features a repetitive expression, while the interior spaces visually connect with the building’s surroundings, such as the Empire State Building, to make guests feel the essence of New York. A bay window design facilitates these interior to exterior connections, and they also allow more natural light to flood the interior than a more typical, angular building would.
The bay window concept has been used for centuries. At the end of the 19th century, it was popularized in the United States for high-rise construction; William Le Baron’s Manhattan Building, a tower completed in 1890 in Chicago, is an early example. To this day, the building’s bay windows allow the interior to connect with the outside in a way a flat facade cannot. The concept was perfect for a boutique hotel in Manhattan West. Therefore, SOM developed floorplans around this idea. Because the hotel rooms would be oriented toward the north and the south, the facade expression at each exposure was designed as a series of bay windows, while the east and west exposures remained mostly flat.
This simple and elegant perimeter layout also satisfied the design team’s keen interest in creating a memorable experience at the top of the building – an undulating series of curves in front of the sky canvas that serves as one of the building’s defining architectural features. This top-of-house interest is particularly important for buildings in New York City, where many vertical structures are designed to culminate in a beautiful crown.
To accentuate the softly curved glass facade geometry, SOM developed a distinct, horizontal reading of glass bands and spandrel ribbons that alternate and stack on top of each other. To make this happen, it was essential to research and test various glazing and spandrel materials.
Because both the building massing and the floorplans were already determined, it was apparent that an opacification option for the floor-to-ceiling vision glass was needed to accommodate specific room-layout requirements. The plan diagram below illustrates the program required opacified glass areas that needed to be concealed from the outside to maintain the monolithic look of the building as an object.
But this need was particularly challenging. The team studied the purity of the alternating glass and spandrel ribbons with three general glass design options.
The first examination focused on a highly transparent glass option with vertical spandrel shadowboxes at opaque zones. This scheme, however, was too random and disruptive to the overall reading of the building. The second study centered around, a reflective glass coating that would hide opaque zones, but this did not fit with the rest of the design aesthetically, and its ability to curve was limited.
The third idea – a dark, tinted, and 5/16-inch outer glass substrate – proved to be best. This option beautifully hides opaque zones during the day. It also makes the potential jumping of the coating from the #2 surface to #3 surface for convex, concave, and flat glass almost impossible to detect on the building facade from the outside.
The facade’s thermal performance at the opacified zones mostly relies on its insulation-filled cavity at the back of the ceramic flood coat’s opaque glass. Because this facade was developed several years ago, however, it is important to note that the glass processing industry has since developed new fabrication technology for online bent curved glass that allows for more flexibility in the location of the coatings, given concave glass geometries (certain more limiting radius restrictions still remain).
Spandrel Material Selection
With the selection of the dark tinted glass scheme, SOM focused on designing the spandrel ribbon area. Although it was important to have a contrast between the ribbons’ curves, the team wanted to make sure that there would be no sharp contrast in color. The design team studied potential dark spandrel materials that could accommodate the curving geometry, and, with the help of Fabbrica – the facade contractor – developed a stone spandrel for both its natural beauty and flexibility. The stone, composed of “crystal black” granite, would also make for a more textured, heavier, and opaque contrast with the glass in the vision zone – and exhibit a dynamic appearance through varying lighting conditions. The team also enhanced the granite ribbon, which was created by Lacroix, by articulating the material with recessed surfaces. The result reveals a smoothness and exhibits a rich contrast to the flame-finished general spandrel stone.
Given site constraints, the massing geometry was rationalized with a desire to limit the defining curves to a minimum number of radii for not only design elegance, but also to simplify the construction of the enclosure fabrication. Besides straight line geometry, only three different radii on the entire perimeter define the floorplates.
The smallest radius used on the curved curtainwall – with dimensions of four feet and ten inches – proved very tight for the production of the hot bent, insulated glass units (IGU) and the curved aluminum extrusions. For the former, the issue was mostly visual, while the challenge the latter was both visual and performative. All of the curved glass was approved prior to development, with the help of full-size samples featuring all project-specific components, such as spacers, coatings, laminates, ceramic frits, and more. Additionally, with the tight radii in mind during initial design stages, the challenge to the glass bending processor was never a question of whether it could be done, but whether the glass could be made beautifully. A subtle but important difference to point out as well was that the production of hot bent glass is one of the most complicated glass fabrication processes, as it requires a lot of know-how and expertise to make the end product truly outstanding.
Aluminum Extrusion Bending
For aluminum extrusion bending, there are various techniques available today. But given the tight radii on this project, the manufacturer utilized a specialized curving process for all curved extrusions that required enhanced tolerances with less distortion. In preparation of the actual bending process, the straight aluminum extrusion is first fully encapsulated in an oversized aluminum sacrificial tube, and the remaining voids are filled with a low temperature melting metal alloy. After the standard three rollers bending process, the assembly is submerged into near boiling water and the low temperature infill metal is melted away. The outer sacrificial tube is discarded and the curved aluminum extrusion is sanded down and coated in a finish. As a rule, designers of curtainwalls with curved extrusions need to carefully consider the process’ inherent production tolerances for critical details, such as stack joints, to ensure continuous air and water tightness in the final assembly.
Curtain Wall Engineering
The unitized curtain wall’s spandrel, with its stack joint, features a vented cavity behind the stone and a double chicken head locating the air barrier at the very back of the system. An aluminum base trim is then added to the back of the assembly after the finished flooring is installed, and a curtain track assembly is placed at the suspended header. The aluminum curtain wall anchor assembly is recessed into a local anchor pocket in the concrete slab. Intermitted Stabilization Anchors (ISA), for facade maintenance operations, are also added as needed at the horizontal joint above the glass. The ISA’s load path back to the slab is then fairly direct.
The vertical mullion is designed as a male-female joint with a traditional American system design. Opacified glass areas are fritted with ceramic on the #3 surface, and the cavity between the back of the glass and the front of the insulation is then vented.
Hospitality construction in New York City, as per code, requires projects to meet stringent natural ventilation standards. Parallel, outward opening windows were originally considered to satisfy these code mandates. After initial prototype mock up testing, however, the design team decided to utilize an operable, awning type window with dimensions of up to six feet and five inches by three feet and six inches. The operable sash is designed to be visually concealed and integrated into the typical mullion dimension to minimize visual impact when seen from the interior as well as from the exterior.
Keenly aware of insolation issues on other projects with concave facade geometries, SOM and consultant Front Inc. also ran simulations that analyzed the potential focusing of sun rays on adjacent buildings and surfaces. These simulations revealed no significant focusing of light rays throughout the year.
The project is located on a block that is zoned with specific Outside Inside Transmission Class (OITC) noise requirements. Therefore, a full scale acoustic testing of three typical curtain wall units was conducted as part of a remedial action plan. Insulated glass make ups comprising, in inches, 5/16 outer lite, 5/8 interstitial space, 1/4 inner lite as well as 5/16 outer lite, 1/2 interstitial space, and 3/8 inner lite, were both tested while structurally glazed to the aluminum framing to substantiate compliance with zoning requirements. The team achieved OITC (ASTM E1332) ratings of 30dB and 32dB for the assembly, for applications on the project at various locations on the facade, in compliance with the remedial action plan.
To confirm typical bay window geometry and advance the enclosure design, the team constructed a full-scale mock-up of one facade bay and hotel room early on in the design phase, with materials simulating the true appearance of the project. With the help of this mock-up, SOM and the developer evaluated different glass make ups, mullion colors, curtain wall unit framing dimensions, and spandrel composition options. This, of course, took a considerable amount of effort, but it was well worth the investment, as it gave all stakeholders assurance that the design was achievable and appropriate.
The design team achieved final visual and performance substantiation through another mock-up with standard SOM testing procedures for structural performance, air, and water tightness.
Stone Spandrel Fabrication
The stone carving was extremely efficient. A bandsaw was used to cut the stone with a curved geometry after the initial flame finishing – allowing for a minimal waste of material. Finished spandrel stone panels were then inspected and approved in a dry lay before shipment to the curtain wall contractor for installation in the individual curtain wall units.
Curtain Wall Unit Assembly
The final unitized curtain wall unit assembly took place at Fabbrica’s facility in Connecticut.
Curtain Wall Installation
The modest curtain wall unit sizes were easy to efficiently transport up the building in the exterior hoist car and staging just in time for installation on the tight floorplate. A mini crawler crane from the floors above was used by the crew to install each unit.
The Pendry Hotel is expected to be completed in 2021, and construction for the entire Manhattan West Development is anticipated to conclude in 2023 with the completion of 2 Manhattan West. By that time, the development will mark the end of the final chapter in a decades-long effort to transform the Far West Side of Manhattan – and bring a new destination to life that also establishes a vital link between the Midtown business district, the Penn Station complex, the north end of Chelsea, and Hudson Yards.
This article was originally published in IGS Magazines Summer 2020 USA Special Edition: Read the full Magazine here for more thought-leadership from those spearheading the industry
Christoph Timm is a Senior Architect with over 20 years of experience in the creative field. During his career Christoph has designed a great variety of projects encompassing products, furniture, street lights, facades and architectural spaces. At SOM, he currently serves as Senior Leader of the Enclosure Group, whose practice is embedded among the various architectural design and engineering studios in the New York office. Most notably Christoph has been responsible for SOM’s podium façade design of 1 World Trade Center.
Christoph’s expertise is in building enclosures, both in their aesthetically crafted appearance in varying light conditions as well as performance. Efficiency and appropriate use of materials with a focus on innovation and techniques new to the building process are among the many considerations central in his design process. Outside of SOM Christoph shares his expertise actively at conferences and industry events. He has lectured on design and building performance related topics in the Americas, Europe, and Asia.