Introduction

Often referred to as a specific material in a wall assembly, an air barrier is in fact a continuity of materials in a building envelope. The prospect of designing an air barrier system can be complicated to a designer who does not consider the consequences of selecting inappropriate, and/or incomplete connections for controlling air leakage, i.e., making the air barrier system continuous. The operative word in the previous sentence is “system.”

The interconnection of materials in a wall assembly must be made to form the air barrier into a system; thereby creating an assembly that can adequately sustain the imposed loads of air pressure and moisture.  The proven-ability of a wall assembly to resist air leakage substantially reduces the potential for condensation from occurring within a wall assembly. When constructing walls with materials that are easily damaged by condensation and/or rain penetration, there is little, if not any tolerance of moisture accumulation or else rot, corrosion and/or mold could be the result.