Recently we sat down with Risa Rottenberg, our New York Office Lead, Building Envelope, to talk about an interesting project she’s worked on, the Hispanic Society Museum in New York City.
Thanks so much for sitting down with us, Risa. Can you tell us about this project and our role in it?
Thanks so much for having me and absolutely. We are the Building Envelope Consultants for the East Building extension of The Hispanic Society Museum and Library.
The Hispanic Society of America was founded in 1904. The original HSML building opened in 1908 and is now known as the Central Building. The cornerstone of the building we’re working on, the East Building, is dated 1916.
View West from Broadway, over Audubon Terrace towards the Hudson River, 1919. East Building at left. Image credit: Byron Company. Museum of the City of New York.
HSML is part of an eight-building research campus and cultural center in Upper Manhattan. It’s the only non-university campus of its time, and rare even today. The campus was designated by the NYC Landmarks Preservation Commission as the Audubon Terrace Historic District in 1979. Audubon Terrace is named for, and located on, the former estate of John James Audubon, the artist and ornithologist.
The scope of our work is divided into two phases. The current phase includes converting the existing Fourth Floor of the museum, which is unconditioned storage space, into a state-of-the-art, climate-controlled Conservation Lab. To support this new use, new MEP and elevator upgrades are required, as well as new roof assemblies for both the mechanical roof and the ornamental copper roofs. We are also recreating the original, massive copper skylight that had been removed in the 1960s.
The second phase will include renovations of the remaining floors, from the Third Floor to the Basement, a new visitor entrance, accessible galleries for permanent and special exhibitions, dedicated space for education, outreach programs, and museum support facilities. All spaces will be modernized with updated environmental conditions consistent with international museum standards. The windows at the First through Third Floors were removed in the 1960s and will be reinstated in this phase. And the exterior space, known as Broadway Terrace, will be restored and enhanced.
Audubon Terrace, Hispanic Society of America, circa 1951. View of the Central Building, East Building, and Broadway Terrace at left. Upper Terrace at centre. With permission from the American Geographical Society Archives, University of Wisconsin-Milwaukee.
Wow, what a great, historic project to be a part of! Can you tell us a bit more about the history of this campus?
Of course. The idea for the campus was an incredibly bold and visionary endeavour. The six original buildings, counter-clockwise from the southwest corner, were for the American Numismatic Society, the Hispanic Society (now known as the Central Building), the Museum of the American Indian (now known as the East Building), the American Geographical Society (now Boricua College), a Library (now known as the North Building) and the Church of Our Lady of Esperanza, all designed by Charles Pratt Huntington.
The two buildings at the western end of the terrace were designed later for the American Academy of Arts and Letters and the National Institute of Arts and Letters. These were designed by McKim, Mead and White and finalized by Cass Gilbert.
Image courtesy the NYC Landmarks Preservation Commission, Designation Report – Audubon Terrace Historic District | LP-1001.
All buildings are in the neo-Italian Renaissance style, grouped around a central courtyard accessed from Broadway, between W155th St and W156th St. As grand as the campus is when you’re there, it’s something of a hidden gem. Not many people know about it.
Perhaps after reading this, they’ll be more inclined to discover this beautiful campus in New York City. What were some of the challenges your team encountered on the project?
HSML’s collection is unmatched outside of Spain for both the quantity of objects and their cultural significance, including master works by El Greco, Velázquez, Goya, and Sorolla. The Conservation Lab we’re working on in Phase One will focus on the treatment of paintings, polychrome sculptures, and works on paper.
As you might guess, climate control is extremely important for this space. We were tasked with improving the thermal performance of the existing exterior walls and roofs, using modelling software, such as THERM for thermal analysis and WUFI for hygrothermal analysis. The existing walls are mass masonry and are over four feet thick in some locations.
In addition, the footprint of mechanical equipment required for the East Building and new Conservation Lab is almost as large as the Lab itself. Because the building is part of a Landmark District, NYC LPC is very careful that the original site lines from the streets and sidewalks be maintained and that the new equipment be as unobtrusive as possible.
East Building Roof and Partial North Façade. Image courtesy Beyer Blinder Belle.
The original copper skylight, which was approximately 35 feet by 23 feet, was removed in the 1960s. The original windows were also removed at this time and infilled with limestone. Replacement of the skylight is part of our current scope of work, and reinstatement of the windows will be included in a future phase of the project.
View of limestone infill when the original windows were removed in the 1960s. Image courtesy Risa Rottenberg.
So at a high level, there were three main challenges to solve: ensuring climate control for the Conservation Lab, replacing the roofing assemblies, and recreating the original skylight. How did you solve these challenges?
For the exterior walls and roofs, we developed a probe package with recommendations to core drill the existing walls and roof slabs at multiple locations on each floor of the building, to estimate the overall thicknesses and determine the material composition.
Partial view of brick and mortar core drill removals at the Exterior Walls. Image courtesy Risa Rottenberg.
The exterior walls are composed of limestone cladding, brick backup, terra cotta furring, and interior plaster. Each material has different thermal and hygrothermal properties so, we needed to approximate the thicknesses of each, at as many representative locations as practical.
For the roofing assemblies, flat roof systems of that era included a large layer of cinder ash fill, both for insulation and to provide slope to drain. Thanks to the improved roofing and insulation materials and systems of today, we will be able to remove the cinder fill and lower the walking surface of the roof by almost two feet, thereby reducing the installed heights and visibility of the new mechanical equipment behind the existing parapet walls.
Finally, for the skylight, we did an additional roof probe at the location of the former skylight to review the original framing, flashing and infill material.
Roof probe at the corner of the former skylight. Images courtesy Wolf Construction.
And luckily a matching copper skylight is still in place across the courtyard, at the former American Geographical Society, now Boricua College. A similar skylight at the Central Building of HSML was also recently replaced. The design team was able to survey both skylights and recreate the historic profiles while integrating modern insulating glass units (IGUs), ventilation, and condensation management. Visible light transmittance, solar height gain coefficients, and condensation resistance were important considerations for the selection of the new glass and frames. Interior, motorized louvers will also be located below the skylight to further control and modulate the amount of natural light with the conservation activities.
Thanks so much for that explanation! Final question, what was your favourite aspect of the project?
It was wonderful to work with such a great team: Beyer Blinder Belle, the Architect of Record, who is our client; Selldorf Architects, who are the Design Architect for the overall Campus Master Plan; and Samuel Anderson Architects, who specialize in Conservation Labs, were leading the helm. Both Silman, the Structural Engineers, and Kohler Ronan, the MEP Engineers, provided invaluable support.
I’m also looking forward to starting construction. Recreating the original copper skylight and roofs will be spectacular.
Thanks so much for your time, Risa! What a beautiful, meaningful project to be working on!