| 9.25.3. |
Air Barrier Systems |
| 9.25.3.1. |
Required Barrier to Air Leakage
- Wall, ceiling and floor assemblies separating conditioned space from unconditioned space or from the ground shall be constructed so as to include an air barrier system that will provide a continuous barrier to air leakage
- from the interior of the building into wall, floor, attic or roof spaces, sufficient to prevent excessive moisture condensation in such spaces during the winter, and
- from the exterior or the ground inward sufficient to
- prevent moisture condensation on the room side during winter,
- ensure comfortable conditions for the occupants, and
- minimize the ingress of soil gas. (See Note A-9.25.3.1.(1).)
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| 9.25.3.2. |
Air Barrier System Properties (See Note A-9.25.5.1.(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.
- Where polyethylene sheet is used to provide airtightness in the air barrier system, it shall conform to CAN/CGSB-51.34-M, "Vapour Barrier, Polyethylene Sheet for Use in Building Construction."
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| 9.25.3.3. |
Continuity of the Air Barrier System
- Where the air barrier system consists of an air-impermeable panel-type material, all joints shall be sealed to prevent air leakage.
- Except as provided in Sentence 9.25.3.6.(3), where the air barrier system consists of flexible sheet material, all joints shall be
- sealed, or
- lapped not less than 100 mm and clamped, such as between framing members, furring or blocking, and rigid panels.
- 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.
- Where an interior wall projects through a ceiling or extends to become an exterior wall, spaces in the wall shall be blocked to provide continuity across those spaces with the air barrier system in the abutting walls or ceiling.
- Where an interior floor projects through an exterior wall or extends to become an exterior floor, continuity of the air barrier system shall be maintained from the abutting walls across the floor assembly.
- Penetrations of the air barrier system, such as those created by the installation of doors, windows, electrical wiring, electrical boxes, piping or ductwork, shall be sealed to maintain the integrity of the air barrier system over the entire surface.
- Where access hatches and sump pit covers are installed through assemblies constructed with an air barrier system, they shall be weatherstripped around their perimeters to prevent air leakage.
- Clearances between chimneys or gas vents and the surrounding construction that would permit air leakage from within the building into a wall or attic or roof space shall be sealed by noncombustible material to prevent such leakage.
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| 9.25.3.4. |
Air Leakage Control in Masonry Walls
(See Note A-9.25.3.4. and 9.25.3.6.)
- Masonry walls required to provide a barrier to the ingress of air from the ground shall
- include a course of masonry units without voids, or
- be sealed with flashing material extending across the full width of the masonry.
- The masonry course or flashing described in Sentence (1) shall
- be located at the level of the adjoining floor and be sealed to it in accordance with Article 9.25.3.6., or
- in the absence of a floor, be located at the level of the ground cover required by Article 9.18.6.1. and be sealed to it.
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| 9.25.3.5. |
Air Leakage Control in Underground Roofs
- Waterproofing systems for roofs of underground structures shall be sealed to the air barrier in the walls.
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| 9.25.3.6. |
Air Barrier Systems in Floors-on-ground
(See Note A-9.25.3.4. and 9.25.3.6.)
- Materials used to provide a barrier to the ingress of air through floors-on-ground shall conform to CAN/CGSB-51.34-M, "Vapour Barrier, Polyethylene Sheet for Use in Building Construction."
- Where the floor-on-ground is a concrete slab, the air barrier shall be
- installed below the slab, or
- applied to the top of the slab, provided a separate floor is installed over the slab. (See Note A-9.25.3.6.(2) and (3).)
- Where the air barrier installed below a floor-on-ground is flexible sheetmaterial, joints in the barrier shall be lapped not less than 300 mm. (See Note A-9.25.3.6.(2) and (3).)
- Where installed in conjunction with a framed floor-on-ground or above a floor-on-ground, the air barrier shall be installed in accordance with Article 9.25.3.3.
- A floor-on-ground shall be sealed around its perimeter to the inner surfaces of adjacent walls using flexible sealant.
- All penetrations of a floor-on-ground that are required to drain water from the floor surface shall be sealed in a manner that prevents the upward flow of air without preventing the downward flow of liquid water.
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