ACH TO 3.2
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).)
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."
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.
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.
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.
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.
ACH TO 2.5
9.36.5.10. MODELING BUILDING ENVELOPE OF PROPOSED HOUSE
9) The airtightness value used in the energy model calculations for the proposed house shall be
a) 3.2 air changes per hour at 50 Pa pressure differential, where the construction complies with Section 9.25.,
b) 2.5 air changes per hour at 50 Pa pressure differential, where it can be shown that the air barrier system is constructed in accordance with Subsection 9.25.3. and Articles 9.36.2.9. and 9.36.2.10., or
c) where airtightness is tested in accordance with Sentence (11), i) the number of air changes per hour at 50 Pa pressure differential, and zii) the equivalent leakage area (see Note A-9.36.5.10.(9)(c)(ii)).
10) A design airtightness shall be assigned for use in the energy model calculations until the actual airtightness has been measured in accordance with Sentence (11).
11) Where measured airtightness is used in the energy model calculations, it shall be determined in accordance with CAN/CGSB-149.10-M, “Determination of the
Airtightness of Building Envelopes by the Fan Depressurization Method,”
a) as written, or
b) excluding Clause 6.1.6, which allows intentional openings for mechanical equipment to be left unsealed. (See Note A-9.36.5.10.(11).)
12) Where airtightness is determined in accordance with Sentence (11) using air
changes per hour, the result obtained at an air pressure differential of 50 Pa shall be
used in the energy model calculations.
13) Where airtightness is determined in accordance with Clause (11)(b), its rate
shall be adjusted in the energy model calculations to account for air leakage through
mechanical equipment.
9.36.2.9. AIRTIGHTNESS
1) The leakage of air into and out of conditioned spaces shall be controlled by constructing
a) a continuous air barrier system in accordance with Sentences (2) to (6), Subsection 9.25.3. and Article 9.36.2.10.,
b) a continuous air barrier system in accordance with Sentences (2) to (6) and Subsection 9.25.3. and a building assembly having an air leakage rate not greater than 0.20 L/(s·m2) (Type A4) when tested in accordance with CAN/ULC-S742, “Air Barrier Assemblies – Specification,” at a pressure differential of 75 Pa, or
c) a continuous air barrier system in accordance with Sentences (2) to (6) and Subsection 9.25.3. and a building assembly having an air leakage rate not greater than 0.20 L/(s·m2) when tested in accordance with ASTM E 2357, “Determining Air Leakage of Air Barrier Assemblies,” where i) the building will not be subjected to sustained wind loads calculated based on a 1-in-50 hourly wind pressure that exceed 0.65 kPa, and ii) the air barrier assembly is installed on the warm side of the thermal insulation of the opaque building assembly. See Note A-9.36.2.9.(1).)
2) An air barrier system installed to meet the requirements of Sentence (1) shall be continuous
a) across construction, control and expansion joints,
b) across junctions between different building materials and assemblies, and
c) around penetrations through all building assemblies.
3) Windows, doors and skylights and their components shall comply with the minimum air leakage requirements stated in
a) AAMA/WDMA/CSA 101/I.S.2/A440, “NAFS – North American Fenestration Standard/Specification for Windows, Doors, and Skylights” (Harmonized Standard), and b) CSA A440S1, “Canadian Supplement to AAMA/WDMA/CSA 101/I.S.2/A440-11, NAFS – North American Fenestration Standard/Specification for Windows, Doors, and Skylights.”
4) Vehicular access doors that separate heated garages from unconditioned spaces or the exterior shall be weatherstripped around their perimeter to prevent air leakage.
5) Fireplaces shall be equipped with doors, enclosures or devices to restrict air movement through the chimney when the fireplace is not in use. (See Note A-9.36.2.9.(5).)
6) Where the airtight material used in the air barrier system is installed toward the exterior of the building envelope, its location and properties shall conform to Subsection 9.25.5. (See Note A-9.36.2.9.(6).) 9.36.2.10.
CONSTRUCTION OF AIR BARRIER DETAILS
1) Materials intended to provide the principal resistance to air leakage shall conform to CAN/ULC-S741, “Air Barrier Materials – Specification.” (See Note A-9.25.5.1.(1) for air leakage characteristics and water vapour permeance values for a number of common materials.)
2) Materials referred to in Sentence (1) shall be
a) compatible with adjoining materials, and
b) free of holes and cracks. (See Note A-9.36.2.10.(5)(b).)
3) Where the air barrier system consists of rigid panel-type material, all joints shall be sealed. (See Note A-9.36.2.10.(5)(b).)
4) Where the air barrier system consists of timber logs, all joints shall be sealed to resist airflow through gaps between logs that have shifted due to in-service conditions such as shrinkage and settling.
5) Where the air barrier system consists of flexible sheet material, all joints shall be
a) lapped not less than 50 mm,
b) sealed (see Note A-9.36.2.10.(5)(b)), and
c) structurally supported.
6) Sealant material used for the purpose of creating a continuous air barrier system shall
a) be a non-hardening type, or
b) conform to i) Subsection 9.27.4., ii) CAN/ULC-S710.1, “Thermal Insulation – Bead-Applied One Component Polyurethane Air Sealant Foam, Part 1: Material Specification,” or iii) CAN/ULC-S711.1, “Thermal Insulation – Bead-Applied Two Component Polyurethane Air Sealant Foam, Part 1: Material Specification.”
7) Penetrations by electrical wiring, outlets, switches or recessed light fixtures through the plane of airtightness shall be constructed airtight
a) where the component is designed to provide a seal against air leakage, by sealing the component to the air barrier material (see Note A-9.36.2.10.(7)(a)), or
b) where the component is not designed to provide a seal against air leakage, by covering the component with an air barrier material and sealing it to the adjacent air barrier material.
8) The joints between the foundation wall and the sill plate, between the sill plate and rim joist, between the rim joist and the subfloor material, and between the subfloor material and the bottom plate of the wall above shall be constructed airtight by
a) sealing all joints and junctions between the structural components, or
b) covering the structural components with an air barrier material and sealing it to the adjacent air barrier material.
9) The interfaces between windows, doors and skylights and wall/ceiling assemblies shall be constructed airtight by sealing all joints and junctions between the air barrier material in the wall and the window, door or skylight frame. (See Note A-9.36.2.10.(9).) (See also Subsection 9.7.6.)
10) Cantilevered floors and floors over unheated spaces or over the exterior shall be constructed airtight by one of the following methods or a combination thereof:
a) sealing all joints and junctions between the structural components, or
b) covering the structural components with an air barrier material and sealing it to the adjacent air barrier material.
11) Interior walls that meet exterior walls or ceilings whose plane of airtightness ison the interior of the building envelope and knee walls that separate conditioned space from unconditioned space shall be constructed airtight by
a) sealing all junctions between the structural components,
b) covering the structural components with an air barrier material and sealing it to the adjacent air barrier material, or
c) maintaining the continuity of the air barrier system above or through the interior wall or below or through the knee wall, as applicable.
12) Steel-lined chimneys that penetrate the building envelope shall be constructed airtight by blocking the void between required clearances for metal chimneys and surrounding construction with sheet metal and sealant capable of withstanding high temperatures.
13) Masonry or concrete chimneys that penetrate the building envelope shall be constructed airtight by mechanically fastening a metal flange or steel stud that extends not less than 75 mm out from the chimney and sealing the air barrier material to it with a sealant capable of withstanding high temperatures. 14) Ducts that penetrate the building envelope shall be constructed airtight by sealing the penetration through the building envelope. (See Note A-9.36.2.10.(14).)
15) Plumbing vent stack pipes that penetrate the building envelope shall be constructed airtight by
a) sealing the air barrier material to the vent stack pipe with a compatible sealant or sheathing tape, or
b) installing a rubber gasket or prefabricated roof flashing at the penetration of the plane of airtightness then sealing it and mechanically fastening it to the top plate.
16) Where a party wall meets the plane of airtightness, that junction shall be constructed airtight by sealing any voids within the party wall at the perimeter to the adjacent air barrier material and by
a) sealing all junctions between the structural components, or
b) covering the structural components with an air barrier material and sealing it to the adjacent air barrier material.
17) Where the concrete in a flat insulating concrete form wall acts as the air barrier, the continuity of the plane of airtightness shall be maintained between the concrete and adjacent air barrier materials.
2.2.8.2. INFORMATION REQUIRED ON DRAWINGS AND SPECIFICATIONS
1) Except as provided in Sentences (2), (3) and (4), the drawings and specifications for the proposed house shall include
a) the effective thermal resistance values and respective areas of all opaque building envelope assemblies, including all above-ground and below-ground
roof/ceiling, wall, and floor assemblies,
b) the overall thermal transmittance (U-value), solar heat gain coefficient and respective areas of all fenestration and door components,
c) the ratio of total vertical fenestration and door area to gross wall area,
d) the performance rating, energy source, and types of all equipment required for space-heating and -cooling and service water heating,
e) the design basis for the ventilation rates,
f) where a test is used to determine the airtightness of a house, the measured airtightness of the building envelope in air changes per hour, and
g) any additional features used in the energy model calculations that account for a significant difference in house energy performance.