| 5.4.1.1. |
Required Resistance to Air Leakage (See Note A-5.4.1.1.)
- 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
- provide acceptable conditions for the building occupants,
- maintain appropriate conditions for the intended use of the building,
- minimize the accumulation of condensation in and the penetration of precipitation into the building component or assembly,
- control heat transfer to roofs where ice damming can occur,
- minimize the ingress of airborne radon from the ground with an aim to controlling the indoor radon concentration to an acceptable level, and
- not compromise the operation of building services.
- Except as provided in Sentence (3), an air barrier system shall be installed to provide the principal resistance to air leakage.
- An air barrier system is not required where it can be shown that uncontrolled air leakage will not adversely affect any of
- the health or safety of building users,
- the intended use of the building, or
- the operation of building services.
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| 5.4.1.2. |
Air Barrier System Properties
- Except as provided in Sentence (2), air barrier materials intended to provide the principal resistance to air leakage shall
- have an air leakage characteristic not greater than 0.02 L/(s·m2) measured at an air pressure difference of 75 Pa, when tested in accordance to ASTM E 2178, "Air Permeance of Building Materials," or
- conform to CAN/ULC-S741, "Air Barrier Materials - Specification." (See Note A-5.4.1.2.(1) and (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 health or safety of the building users,
- the intended use of the building, or
- the operation of building services. (See Note A-5.4.1.2.(1) and (2).)
- The air barrier system shall be continuous
- across construction, control and expansion joints,
- across junctions between different building assemblies, and
- around penetrations through the building assembly.
- 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.
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