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According to the 2020 National Building Code of Canada, air barrier systems must have the following properties:

9.25.3.2. Air Barrier System Properties

(1) Air barrier systems shall possess the characteristics necessary to provide an effective barrier to air infiltration and exfiltration under differential air pressure due to stack effect, mechanical systems or wind.

(2) Where polyethylene sheet is used to provide the air-tightness in the air barrier system, it shall conform to CAN/CGSB-51.34-M, "Vapour Barrier, Polyethylene Sheet for Use in Building Construction".

The NBC also describes the specific material performance properties in 9.25.5. Properties and Position of Materials in the Building Envelope.

Sheet and panel materials shall conform to...

(1) air leakage characteristic less than 0.1 L/(second per m2) at 75 Pascals,

(2) a water vapour permeance less than 60 ng/(Pascals per second per m2) when measured in accordance with ASTM E96/E96M,

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Installation must meet Part 9.25.3.3 Continuity of the Air Barrier Systems

9.25.3.1. Required Barrier to Air Leakage

1. Where the air barrier system consists of an air-impermeable panel-type material, all joints shall be sealed to prevent air leakage.
2. Except as provided in Sentence 9.25.3.6.(3), where the air barrier system consists of flexible sheet material, all joints shall
   1. be sealed, or
   2. lapped not less than 100 mm and clamped, such as between framing members, furring or blocking, and rigid panels.
3. Where an interior wall meets an exterior wall, ceiling, floor or roof required to be provided with air barrier protection, the air barrier system shall extend across the intersection.