Division B
Acceptable Solutions
Part 5 — Environmental Separation
Section 5.4. Air Leakage
(See Appendix A and Part 10.)5.4.1. Air Barrier Systems
5.4.1.1. Required Resistance to Air Leakage
(See Appendix A.)1) 
Where a building component or assembly separates interior conditioned space from exterior space, interior space from the ground, or environmentally
dissimilar interior spaces, the properties and position of the materials
and components in those components or assemblies shall be such that
they control air leakage or permit venting to the exterior so as to
Where a building component or assembly separates interior conditioned space from exterior space, interior space from the ground, or environmentally
dissimilar interior spaces, the properties and position of the materials
and components in those components or assemblies shall be such that
they control air leakage or permit venting to the exterior so as toa) provide acceptable conditions for the building occupants,
b) maintain appropriate conditions for the intended use of the building,
c) minimize the accumulation of condensation in and the penetration
of precipitation into the building component or assembly,
d) control heat transfer to roofs where ice damming can occur,
e) 
minimize the ingress of airborne radon from the ground with an aim to controlling the indoor radon concentration to
an acceptable level, and
minimize the ingress of airborne radon from the ground with an aim to controlling the indoor radon concentration to
an acceptable level, andf) not compromise the operation of building services.
2) Except as provided in Sentence (3), an air barrier system shall be installed to provide the principal resistance to air leakage.
Except as provided in Sentence (3), an air barrier system shall be installed to provide the principal resistance to air leakage.
3) An air barrier system is not required where it can be shown that uncontrolled air leakage will not adversely affect any of
An air barrier system is not required where it can be shown that uncontrolled air leakage will not adversely affect any ofa) the health or safety of building users,
b) the intended use of the building, or
c) the operation of building services.
5.4.1.2. Air Barrier System Properties
1) Except as provided in Sentence (2), materials intended to provide the principal resistance to air leakage shall
Except as provided in Sentence (2), materials intended to provide the principal resistance to air leakage shalla) have an air leakage characteristic not greater than 0.02
L/(s•m2) measured at an air pressure difference of
75 Pa, or
(See Appendix A.)2) The air leakage limit specified in Sentence (1) is permitted to be increased where it can be shown that the higher rate of leakage will
not adversely affect any of
The air leakage limit specified in Sentence (1) is permitted to be increased where it can be shown that the higher rate of leakage will
not adversely affect any ofa) the health or safety of the building users,
b) the intended use of the building, or
c) the operation of building services.
(See Appendix A.)3) The air barrier system shall be continuous
The air barrier system shall be continuousa) across construction, control and expansion joints,
b) across junctions between different building assemblies, and
c) around penetrations through the building assembly.
4) The structural design of air barrier systems installed in assemblies subject to air pressure loads shall comply with Article 5.1.4.1. and Subsection 5.2.2.
The structural design of air barrier systems installed in assemblies subject to air pressure loads shall comply with Article 5.1.4.1. and Subsection 5.2.2.