Tammany Hall’s High-tech Glass Dome Honors New York’s Original People

Coincidentally, the Mansueto Library’s form and use closely resembled our intentions to create a glass-domed workspace. We noted how the fritted glass of Mansueto Library’s dome performs exceptionally well and was virtually invisible, creating a very low-glare environment with the illusion of clear glass. Our team was inspired to use a similar strategy but quickly learned through sample and mock-up iterations, the effect achieved at Mansueto Library is because of the height of the fritted glass above the occupants; the higher the better.


WORKING WITH BKSK, THE ENGINEERING TEAM OPTIMIZED THE DOME’S GEOMETRY TO ACHIEVE THE MOST EFFICIENT USE OF REPEATED GLASS SIZES AND STEEL SHAPES.

We learned when frit is closer to one’s eyes, direct sunlight can be perceived between fritted patches, reaching occupants’ eyes, rendering even very closely placed frit useless. We moved on to study combinations of frit, film and tinted glass and eventually chose two insulated-glass-unit assemblies using a combination of clear and tinted glass.

The slightly clearer of the two assemblies encloses the lower areas of the dome where Tammany’s small hipped roof once stood. Terra-cotta sunshades protect portions of this lower tier in the same inclined plane as slate tiles once sat. Strategic placement of projecting painted stainless-steel fins on the exterior of the upper dome offer articulation to the shell and also provide rain and snow control. The most rewarding aspect of the finished project was maintaining a legible image of a rising turtle throughout design and construction using cutting-edge technology and practical everyday elements.

The glass-domed vertical enlargement encloses an additional 30,000 square feet of rentable space over three floors on the top of the historic building with dynamic views of Union Square and beyond. The dome is comprised of more than 2,000 2- by 6-inch steel tube purlins with customized node intersections and varying wall thickness depending on location.

The glass product is a structurally glazed insulated glass unit comprised of a clear float glass panel with a high-performance sputter coat solar coating on surface two, an air space and two layers of laminated glass.

The glass product is a structurally glazed insulated glass unit comprised of a clear float glass panel with a high-performance sputter coat solar coating on surface two, an air space and two layers of laminated glass: a tinted gray panel and a clear glass panel facing the interior.

The solar coating on surface two is an extremely high selectivity solar control with advanced thermal insulation properties for commercial glazing. It is applied by cathodic sputtering under vacuum conditions. The coating creates a low solar factor to reduce air-conditioning load and has a U-value of 1.0W/m2K, encouraging energy savings and improved thermal insulation. Neither too green nor too blue in appearance, the insulated glass units at Tammany Hall’s dome retain a neutral appearance.

A central challenge during the construction phase involved decoupling the historic 100-year-old street walls from the internal structure of the building, bracing them externally, restoring them and then securing them back to a newly poured concrete structure behind. Unexpectedly, it proved more efficient for CNY to remove the lot-line walls against the adjacent neighbors, as well, during demolition of the internal structure, leaving only the historic street walls as original fabric from 1928. The resulting building is truly a new Class A commercial mixed-use building referencing the past and ready for tomorrow. The building received a core and shell temporary certificate of occupancy in 2020 and is being actively marketed by ownership.

Retrofit Team

OWNER: Reading International RDI

OWNER’S REPRESENTATIVE: Edifice Real Estate Partners

ARCHITECT: BKSK Architects LLP

STRUCTURAL ENGINEER: Thornton Tomasetti

EXTERIOR ENVELOPE ENGINEER: Buro Happold

Tammany Hall in 1935. BEFORE PHOTO: courtesy BKSK Architects

MEPS ENGINEER: Dagher Engineering

VERTICAL TRANSPORTATION ENGINEER: IROS Elevator

CONSTRUCTION MANAGER: CNY

DOME STEEL AND GLASS FABRICATOR/INSTALLER: Josef Gartner, a division of Permasteelisa

HISTORIC PRESERVATION CONSULTANT: Higgins Quasebarth & Partners LLC

Materials

DESIGN SOFTWARE: Rhino 3D, V-Ray by Chaos Group, Autodesk Maya, Autodesk 3ds Max and Autodesk Revit

CLEAR AND TINTED GLASS: Eckelt, a member of Saint-Gobain

  • CLEAR FLOAT GLASS PANEL: PLANICLEAR
  • TINTED GRAY PANEL: Parsol Grey
  • SOLAR COATING: COOL-LITE XTREME

AFTER PHOTOS: Christopher Payne | Esto


About the Author

Todd Poisson, AIA
As a partner at BKSK Architects LLP with more than 25 years’ experience, Todd Poisson, AIA, has been responsible for the design and construction of some of BKSK Architects’ most ambitious projects.

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