The 5 Criteria for Evaluating Air Barrier Systems in Buildings
Air barrier systems in buildings are marketed as systems because many different types of materials must combine to make an airtight plane that controls airflow. The critical areas for any airtight plane are a building’s material transitions, penetrations, and joints.
5 important criteria to use when judging or comparing air barrier systems:
1) Continuity. Air barrier systems must be continuous. Without continuity, there is no point in considering the system’s other performance qualities. At the buying or comparison stage of the process, it’s important to understand how easily continuity can be achieved.
2) Strength. The air barrier system must be capable of enduring winds and transferring wind loads to the structure without tearing.
3) Durability. The air barrier must stand up to the stresses of building construction, since it will go up—especially an exterior system—early in the construction process. Overall lifespan and ease of repairs or replacement are also important factors to consider.
4) Stiffness. Air barriers must not only absorb and transfer wind loads, but they also must distribute loads evenly. Stiffness not only helps with wind pressure, but it is very important to the function of the rain-screen, the part of the enclosure that manages bulk water.
5) Impermeability. As the name implies, an air barrier is impermeable by air. It’s impossible to stop all air leakage, but there are standardized leakage rates for residential and commercial properties (link to post #9).
There are many air barrier systems available on the market, but it’s important to choose one that performs well in these five areas, given the incredible benefits a good air barrier has on a building. Here is more information on air barriers.