A combination of materials within wall and roof assemblies which establish a continuous plane of airtightness in the building envelope. Its most important function is moisture control, but it also plays a significant role in energy efficiency, rain control and external noise protection. The system has to meet four requirements: a sufficiently low air permeance, continuity at all joints and intersections, strength against peak wind pressures, and the ability to meet these functions over the service life of the system (durability). These criteria apply to all air barrier components: boards, films, fasteners, gaskets, sealants, etc. Additional points to be considered in the design and assembly of air barrier systems are the accessibility for maintenance and the certification of specialised trades, in order to ensure that air barrier systems are installed at a consistent quality in practice .
 NRC, 1997. Air barrier systems for walls of low-rise buildings: performance and assessment. Canadian Construction Materials Centre, National Research Council Canada, Ottawa, Ontario.
Posted in: Building Airtightness