Track 2: Materials over Time: Points of Change

General Abstract

Case Study of the Restoration of a 41-Story Post-Modern Façade: Material Failures and Advancements

Monday, September 24
10:30 AM - 12:00 PM
Location: BNCC- 101BG

As the frequency of high-rise construction increased during the mid-20th century, materials used along the building envelope evolved to address the constructability of these post-modern designs. In turn, exterior wall systems have drastically evolved over the past decades due to technological advancements, lessons learned, and as a response to energy codes. This presentation will utilize a case study on the restoration of a 41-story post-modern building to discuss the failures and advancements of three common post-modern materials: stone cladding, insulation, and windows systems.

Like many post-modern high rises, the subject 41-story building is comprised of stone cladding backed with fiberglass insulation, and a series of ribbon windows. The stone cladding is approximately three-inches thick and backed with a rigid fiberglass insulation board. The window system is comprised of a single aluminum extrusion with double-pane glass.

After 40+ years of service, the building experienced multiple façade failures, which is becoming more common at other post-modern high-rises. These failures included water infiltration through the stone cladding and windows, and condensation at their associated framing members. These post-modern materials and their associated interfaces, although progressive in their time, contain many water and thermal issues that would not meet today’s design standards. Post-modern exterior wall systems can be closely defined as a “barrier” system, as the wall has little to no redundancy to manage infiltrated storm water. In addition, the thermal layer of the wall contains a low R-value and is non-continuous, which can cause condensation to occur within the interior spaces. Thus, these lessons learned along with the advancement of energy codes have lead the way for the development of new materials used in current construction.

Stone claddings can now be produced at thicknesses less than one-inch with new fabrication methods and anchors. Advancements in mineral wool and spray foam insulation has superseded fiberglass insulation which was common during mid-century construction. Glazing systems have progressed from single frame extrusions to multi-component thermally-broken assemblies. Low-emissive coatings on glazing was developed to address thermal comfort issues and improve energy performance. Insulating joint materials have been conceived to provide thermal continuity between building components.

Our team’s work scope included the investigation, analysis, and repair of the 41-story post-modern building, which included thermographic studies of the façade materials. Through the case study, the presentation will compare and contrast the materials used in post-modern buildings to current material advancements.

Learning Objectives:


Senior Project Architect
Thornton Tomasetti

Lee Fink is an senior project architect with Thornton Tomasetti. Lee is in the Forensics and Renewal practices and specializes in the high-rise facades, with a focus on glazing and stone systems. Although most of his projects reside in his hometown of Chicago, IL, his facade experience ranges from envelopes in Texas to Dubai.


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Chris Gembinski

Building Conservation Associates, Inc.


Chris is the Director of Technical Services for Building Conservation Associates, Inc., providing quality control and technical oversight for all BCA projects. Through his investigative work on hundreds of historic properties, he has developed extensive expertise in historic construction techniques and building systems, architectural materials, preservation design solutions, and construction management. Various aspects of his research and design have included masonry restoration, plaster restoration, historic finishes analysis, wood and metal window restoration design and stained-glass restoration. His work includes the design and management of conservation and preservation construction for: The Metropolitan Life Insurance Building, Grand Central Terminal, St. Patrick’s Cathedral, the Central Park Police Precinct, the Cathedral Church of St. John the Divine, and Trinity Chrch, Wall Street, as well as development ventures such as the Victoria Theater and Moynihan Station Redevelopments.


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Lorraine Schnabel

Schnabel Conservation LLC

Lorraine Schnabel is the principal and owner of Schnabel Conservation LLC, a full service materials conservation consulting firm. We work with preservation project teams to diagnose whole building and individual material deterioration problems and identify workable, practical, durable solutions. After nearly thirty years in practice as both a private conservator and as a project manager at John Milner Associates and 1:1:6 Technologies, Lorraine has developed experience with most types of building materials and historic construction systems. Her principle areas of expertise are masonry and materials analysis. She has applied her skills in the preservation of a broad range of building ages and types, from small historic houses to the Baltimore Washington Monument. Currently, she is co-chair of the APT Technical Committee for Materials, and she has served on the board of the Delaware Valley chapter of APT as well. She is a Fellow of the American Institute for Conservation of Historic and Artistic works, and served in leadership roles in the Architecture Specialty Group and Conservators in Private Practice of that organization. She teaches Building Conservation to students in the College of Architecture and the Built Environment at Jefferson (formerly Philadelphia) University. Lorraine holds a BA in Geology from Pomona College and an MSc. in Historic Preservation from Columbia University.


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Case Study of the Restoration of a 41-Story Post-Modern Façade: Material Failures and Advancements

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