Air Barrier Performance Requirements

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There are four main performance requirements for air barriers: air infiltration resistance, continuity, structural integrity, and durability.

Air infiltration resistance: An air barrier must resist airflow. While there are no mandatory requirements at the national level, individual states have adopted energy conservation codes that require air tightness and allow for different compliance options for air infiltration resistance of air barrier materials, assemblies, or whole buildings (as previously described).

Wetting vs. Drying of Building Enclosure

Uncontrolled air leakage could negatively impact building occupant comfort, durability of building materials, and energy consumption levels. Air barriers play a critical role in controlling these effects of air leakage.



1. Bulk Water

2. Airtransport

Drying 1. Diffusion

Continuity is a critical requirement for air barriers, and depends on both design and execution. The first step is to detail the air barrier continuity in the drawings. "A continuous line of air tightness must be traced through every exterior wall detail, and every connection between air barrier components," says Spinu. The most critical connections include: the roof and wall; wall and foundation; wall and floors; wall and window or door interfaces; joints between various types of exterior wall systems, and penetration details. The design details must then be properly implemented in the field. The air barrier system includes the primary air barrier membranes and the installation and continuity accessories, such as mechanical fasteners, tapes, flashing, caulks, sealants, and primers.

The multiple consequences of uncontrolled airflow may result in potential liability issues for the entire building community. Architects, consultants, and engineers could be held liable for moisture damage in buildings because of faulty design or poor material selection. Contractors' workmanship can be called into question when water damage is due to poor execution of the intended design or unauthorized material substitution. Building owners may be held responsible for poor indoor air quality, mold problems or lack of thermal comfort. With serious consequences for the design and building industry professionals, building owners and building users, it behooves all members of the building team to pay close attention to controlling unwanted air flow and selecting the proper barrier method.

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