Within many commonly used exterior opaque wall assemblies, the air and water control layers are provided by a single material with a combined function, indicated as an air and water barrier (AWB). When integrating glazing into the wall assembly, transitions between the AWB and fenestration1 assemblies are created. It is at these transitions where many post construction issues originate. As such, these transitions need to be carefully designed and coordinated during construction, since these transitions typically include the work of multiple trades/installers. Discontinuities in this continuous air and water seal between the AWB and the fenestration can result in air and water infiltration to the building interior.
Like many building materials, selection of fenestration systems for specific wall assemblies is a process in which performance characteristics such as structural capacity, the resistance to air infiltration, water penetration, and thermal attributes are evaluated along with aesthetics and cost. However, the integration of the system(s) under consideration with the adjacent exterior wall assembly is often overlooked in the selection process.2