What does an effective air barrier system need to withstand?

An effective air barrier system must be designed to withstand both positive and negative loads. This is crucial because the air barrier is responsible for preventing unintentional air movement that can lead to energy loss, moisture problems, and overall deterioration of building materials. Positive loads occur when air pressure inside a building exceeds that outside (such as during heating), and negative loads happen when outside air pressure is greater, often influenced by wind or stack effect. By effectively handling both scenarios, the air barrier contributes to the overall performance, energy efficiency, and durability of the building envelope.

While high humidity levels can affect materials and extreme temperatures can impact performance, it is the pressure differences that directly test the integrity of the air barrier system. Similarly, while physical impacts from construction activities are a concern, they pertain more to the design and material selection rather than the fundamental requirement of the air barrier to function under varying pressure conditions.