Which of the following is NOT an exterior air barrier system?

Sealed polyethylene is primarily used as a vapor barrier rather than an air barrier in building construction. While it can contribute to reducing air leakage, it is typically installed on the interior side of walls or ceilings to control moisture levels within the structure. In contrast, effective exterior air barriers are designed to prevent air infiltration and exfiltration at the building envelope level and are usually more integrated into the structure's exterior.

Liquid applied membranes, sealed sheathing, and exterior insulation are all designed specifically to act as exterior air barrier systems. They help to create a continuous barrier against air movement, ensuring the energy efficiency and comfort of the building. Each of these options provides a protective layer that effectively mitigates unwanted air flow at the exterior, whereas sealed polyethylene does not serve this specific function in typical construction practices.