Track 2: Materials over Time: Points of Change
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 Advancements in mineral wool and spray foam insulation has superseded fiberglass insulation which was common during mid-century construction.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.
- Identify post-modern construction and its associated building materials, and acknowledge the performance characteristics of these assemblies.
- Recognize failures in post-modern materials and assemblies (whether through failure in the material itself or failure to meet current design standards).
- Understand the development and advancement of common materials used during post-modern construction, and compare them to modern technology and current design standards.
- Develop conceptual repair scopes for the remedy of common material failures found in post-modern construction.