Restoration and Replacement of Glazed Curtain Wall Assemblies

Buildings with large areas of glass are often seen as emblematic of the wanton energy waste of the mid- to late-twentieth century. New York City Mayor Bill DeBlasio has even threatened to ban them. However, given recent advancements in high-performance building technology, meeting energy goals need not be at odds with preserving the unimpeded views, natural daylight, and modern look that a well-designed glass-clad structure can offer.

Beginning with an overview of curtain wall deficiencies, this course provides background on what can go wrong in glass facade assemblies, particularly as they age. From poor thermal performance and damaged glass to water intrusion and condensation, the problems that lead building owners to seek remedial measures can be both unsightly and hazardous. They may also be wasting heating and cooling dollars and causing building interiors to be uncomfortable, noisy, drafty, and damp.

Once owners have determined that an overhaul of the curtain wall is in order, they will need to determine whether a full replacement is appropriate, or whether rehabilitation measures would be better suited to their needs. The design professional should guide the owner through the process of evaluating project goals, considering potential disruption, future maintenance demands, return on investment, structural capacity, and applicable code requirements, along with aesthetics. Options for restoration include gasket replacement, wet glazing, frame recoating, glass films, and glass replacement.

Should full replacement be selected, the design professional will need to determine which type of curtain wall assembly is best suited: stick or unitized, water management or pressure-equalized, and exterior or interior glazed, among other options.

LEARNING OBJECTIVES

After reading this article, you should be able to:

• Diagnose common deficiencies in glazed curtain wall assemblies, including poor thermal performance, water intrusion, compromised glass, and framing deterioration, so as to evaluate existing systems for distress and failure.
• Compare rehabilitation and replacement options using criteria such as disruption to occupants, weight, maintenance demands, payback period, and code requirements, allowing for an informed decision about the best strategy for addressing deficiencies.
• Consider bird safety when designing new, retrofit, and replacement glazed curtain wall assemblies by applying principles of bird-safe design outlined by conservation organizations, green building rating systems, and government regulations.
• Evaluate curtain wall options for energy efficiency, noise resistance, light transmission, fire protection, and other design criteria, and apply quality assurance performance testing to assess air and water penetration resistance and confirm that the specified system meets project goals.