9.36.2. Building Envelope

9.36.2. Building Envelope
9.36.2.1. Scope and Application
  1. Except as provided in Sentence (2), this Subsection is concerned with the loss of energy due to heat transfer and air leakage through materials, components and assemblies, including their interfaces, forming part of the building envelope where it separates conditioned space from unconditioned space, the exterior air or the ground.
  2. The requirements of this Subsection also apply to components of a building envelope assembly that separate a conditioned space from an adjoining storage garage, even if the storage garage is intended to be heated. (See Notes A-9.36.2.1.(2) and A-9.36.1.3.(5).)
  3. Except for skylight shafts addressed in Sentence 9.36.2.6.(4), for the purpose of this Subsection, wall assemblies inclined less than 60° from the horizontal shall be considered as roof assemblies, and roof assemblies inclined 60° or more from the horizontal shall be considered as wall assemblies.
  4. The properties, performance and installation of windows, doors and skylights shall also conform to Section 9.7.
  5. 5) The properties, location and installation of thermal insulation, air barrier systems, vapour barriers, and materials with low air or vapour permeance shall also conform to Section 9.25.
9.36.2.2. Determination of Thermal Characteristics of Materials, Components and Assemblies
  1. The thermal characteristics of materials shall be determined by calculation or by testing in accordance with the applicable product standards listed in the Code or, in the absence of such standards or where such standards do not address the determination of thermal resistance, in accordance with
    1. ASTM C 177, "Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of the Guarded-Hot-Plate Apparatus," or
    2. ASTM C 518, "Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus." (See Table A-9.36.2.4.(1)-D for the thermal characteristics of commonly used materials.)
  2. Calculations and tests performed in accordance with Sentence (1) shall be carried out at an average temperature of 24±2°C and under a temperature differential of 22±2°C.
  3. The thermal characteristics of windows, doors and skylights shall be determined by calculation or testing in accordance with
    1. CSA A440.2/A440.3, "Fenestration Energy Performance/User Guide to CSA A440.2-14, Fenestration Energy Performance," for the reference sizes listed therein, or
    2. NFRC 100, "Determining Fenestration Product U-factors," and NFRC 200, "Determining Fenestration Product Solar Heat Gain Coefficient and Visible Transmittance at Normal Incidence," for the reference sizes listed therein. (See Note A-9.36.2.2.(3).)
  4. The effective thermal resistance of opaque building assemblies shall be determined from
    1. calculations conforming to Article 9.36.2.4., or
    2. laboratory tests performed in accordance with ASTM C 1363, "Thermal Performance of Building Materials and Envelope Assemblies by Means of a Hot Box Apparatus," using an indoor air temperature of 21±1°C and an outdoor air temperature of -18±1°C.
  5. The thermal characteristics of log walls shall be determined by calculation in accordance with Section 305 of ICC 400, "Design and Construction of Log Structures." (See Note A-9.36.2.2.(5).)
9.36.2.3. Calculation of Ceiling, Wall, Fenestration and Door Areas
  1. The gross ceiling or roof area shall be calculated as the sum of the interior surface areas of insulated ceiling and/or roof assemblies and of skylight openings.
  2. Except as permitted by Sentence (3), the gross wall area shall be calculated as the sum of the interior surface areas of all exterior building envelope assemblies above the finished ground level that are inclined 60° or more from the horizontal, including
    1. rim joists,
    2. fenestration and opaque portions of doors,
    3. insulated walls extending from finished ground level to the interior side of the insulated ceiling and/or roof assembly, and
    4. the exposed areas of below-ground building envelope assemblies, where fenestration or doors are located below the plane of the adjacent finished ground. (See Note A-9.36.2.3.(2) and (3).)
  3. Where a building of residential occupancy contains more than 2 dwelling units, the gross wall area enclosing conditioned space shall be permitted to include the interior surface areas of walls that enclose a suite, measured from the top surface of the lowest floor to the underside of the highest ceiling in the suite. (See Note A-9.36.2.3.(2) and (3).)
  4. Fenestration and door areas shall be the actual sizes of windows, doors and skylights including all related frame and sash members.
  5. The fenestration area made of flat panes that are not all in the same plane or curved panes shall be measured along the surface of the glass. (See Note A-9.36.2.3.(5).)
9.36.2.4. Calculation of Effective Thermal Resistance of Assemblies
  1. In calculating the effective thermal resistance of assemblies for the purpose of comparison with the requirements of Articles 9.36.2.6. and 9.36.2.8., the thermal bridging effect of closely spaced, repetitive structural members, such as studs and joists, and of ancillary members, such as lintels, sills and plates, shall be accounted for. (See Note A-9.36.2.4.(1).)
  2. Minor penetrations through assemblies, such as pipes, ducts, equipment with through-the-wall venting, packaged terminal air conditioners or heat pumps, shelf angles, anchors and ties and associated fasteners, and minor structural members that must partially or completely penetrate the building envelope to perform their intended function need not be taken into account in the calculation of the effective thermal resistance of that assembly.
  3. Major structural penetrations, such as balcony and canopy slabs, beams, columns and ornamentation or appendages that must completely penetrate the building envelope to perform their intended function, need not be taken into account in the calculation of the effective thermal resistance of the penetrated assembly, provided
    1. the insulation is installed tight against the outline of the penetration, and
    2. the sum of the areas of all such major structural penetrations is limited to a maximum of 2% of the gross wall area calculated as described in Sentence 9.36.2.3.(2). (See Note A-9.36.2.4.(3).)
  4. Where a component of the building envelope is protected by an enclosed unconditioned space, such as a sun porch, enclosed veranda, vestibule or attached garage, the required effective thermal resistance of the building envelope component between the building and the unconditioned enclosure is permitted to be reduced by 0.16 (m2·K)/W. (See Note A-9.36.2.4.(4).)
9.36.2.5. Continuity of Insulation
  1. Except as provided in Sentences (2) to (9) and in Sentence 9.36.2.4.(3) regarding balcony and canopy slabs, and except for clearances around components required for fire safety reasons, interior building components that meet building envelope components and major structural members that partly penetrate the building envelope shall not break the continuity of the insulation and shall not decrease the effective thermal resistance at their projected area to less than that required in Articles 9.36.2.6. and 9.36.2.8. (See Note A-9.36.2.5.(1).)
  2. Where an interior wall, foundation wall, firewall, party wall or structural element penetrates an exterior wall or insulated roof or ceiling and breaks the continuity of the plane of insulation, the penetrating element shall be insulated
    1. on both of its sides, inward or outward from the building envelope, for a distance equal to 4 times its uninsulated thickness to an effective thermal resistance not less than that required for exterior walls as stated in Table 9.36.2.6.-A or 9.36.2.6.-B,
    2. within the plane of insulation of the penetrated element to an effective thermal resistance not less than 60% of that required for the penetrated element, or
    3. within itself to an effective thermal resistance not less than that required for the penetrated element. (See Note A-9.36.2.5.(2).)
  3. Where a masonry fireplace or flue penetrates an exterior wall and breaks the continuity of the plane of insulation, it shall be insulated within the plane of insulation of the wall or within itself to an effective thermal resistance not less than 55% of that required for the exterior wall as stated in Table 9.36.2.6.-A or 9.36.2.6.-B (See Note A-9.36.2.5.(3).)
  4. Where an ornamentation or appendage penetrates an exterior wall and breaks the continuity of the plane of insulation, the penetrating element shall be insulated
    1. on both of its sides, inward or outward from the building envelope, for a distance equal to 4 times the insulated thickness of the exterior wall to an effective thermal resistance not less than that required for the wall as stated in Table 9.36.2.6.-A or 9.36.2.6.-B,
    2. within the plane of insulation of the wall to an effective thermal resistance not less than 55% of that required for the exterior wall, or
    3. within the penetrating element to an effective thermal resistance not less than that required for the exterior wall.
  5. Except as provided in Sentences (8) and (9), where two planes of insulation are separated by a building envelope assembly and cannot be physically joined, one of the planes of insulation shall be extended for a distance equal to at least 4 times the thickness of the assembly separating the two planes. (See Note A-9.36.2.5.(5).)
  6. Where mechanical, plumbing or electrical system components, such as pipes, ducts, conduits, cabinets, chases, panels or recessed heaters, are placed within and parallel to a wall assembly required to be insulated, the effective thermal resistance of that wall at the projected area of the system component shall be not less than that required by Tables 9.36.2.6.-A, 9.36.2.6.-B, 9.36.2.8.-A and 9.36.2.8.-B (See Note A-9.36.2.5.(6).)
  7. Except as permitted by Article 9.36.2.11., where mechanical ducts, plumbing pipes, conduits for electrical services or communication cables are placed within the insulated portion of a floor or ceiling assembly, the effective thermal resistance of the assembly at the projected area of the ducts, pipes, conduits or cables shall be not less than 2.78 (m2·K)/W.
  8. Joints and junctions between walls and other building envelope components shall be insulated in a manner that provides an effective thermal resistance that is no less than the lower of the minimum values required for the respective adjoining components. (See Note A-9.36.2.5.(8).)
  9. Sentence (1) does not apply where the continuity of the insulation is interrupted
    1. between the insulation in the foundation wall and that of the floor slab,
    2. by an integral perimeter footing of a slab-on-grade (see Sentences 9.25.2.3.(5) and 9.36.2.8.(8)), or
    3. at the horizontal portion of a foundation wall that supports masonry veneer and is insulated on the exterior.
9.36.2.6. Thermal Characteristics of Above-ground Opaque Building Assemblies
  1. Except as provided in Sentences (2) and 9.36.2.8.(3) and Articles 9.36.2.5. and 9.36.2.11., the effective thermal resistance of above-ground opaque building assemblies or portions thereof shall be not less than that shown for the applicable heating-degree day category in
    1. Table 9.36.2.6.-A, where the ventilation system does not include heat-recovery equipment, or
    2. b) Table 9.36.2.6.-B, where the ventilation system includes heat-recovery equipment conforming to Article 9.36.3.9. (See Note A-9.36.2.6.(1).)

      Table 9.36.2.6.-A
      Effective Thermal Resistance of Above-ground Opaque Assemblies in Buildings without a Heat-Recovery Ventilator
      Forming Part of Sentence 9.36.2.6.(1)

      Table 9.36.2.6.-A Effective Thermal Resistance of Above-ground Opaque Assemblies in Buildings without a Heat-Recovery Ventilator


      Notes to Table 9.36.2.6.-A:
      (1) See Article 1.1.3.1.
      (2) See Sentence 9.36.2.8.(3) for requirements concerning the above-ground portion of foundation walls.

      Table 9.36.2.6.-B
      Effective Thermal Resistance of Above-ground Opaque Assemblies in Buildings with a Heat-Recovery Ventilator
      Forming Part of Sentence 9.36.2.6.(1)

      Table 9.36.2.6.-B Effective Thermal Resistance of Above-ground Opaque Assemblies in Buildings with a Heat-Recovery Ventilator

      Notes to Table 9.36.2.6.-B:
      (1) See Article 1.1.3.1.
      (2) See Sentence 9.36.2.8.
      (3) for requirements concerning the above-ground portion of foundation walls.

  2. The effective thermal resistance of rim joists shall be not less than that required for above-ground walls in Table 9.36.2.6.-A or 9.36.2.6.-B, as applicable.
  3. A reduction in the effective thermal resistance of ceiling assemblies in attics under sloped roofs is permitted for a length no greater than 1 200 mm but only to the extent imposed by the roof slope and minimum venting clearance, provided the nominal thermal resistance of the insulation directly above the exterior wall is not less than 3.52 (m2·K)/W. (See Note A-9.36.2.6.(3).)
  4. Except for tubular daylighting devices, the minimum effective thermal resistance values for walls stated in Tables 9.36.2.6.-A and 9.36.2.6.-B shall also apply to shafts for skylights.
9.36.2.7. Thermal Characteristics of Fenestration, Doors and Skylights
  1. Except as provided in Sentences (2) to (8) and Article 9.36.2.11., fenestration and doors shall have an overall thermal transmittance (U-value) not greater than, or an Energy Rating not less than, the values listed in Table 9.36.2.7.-A for the applicable heating-degree day category. (See Note A-9.36.2.7.(1) and (2).)


    Table 9.36.2.7.-A
    Required Thermal Characteristics of Fenestration and Doors
    Forming Part of Sentence 9.36.2.7.(1)

    Table 9.36.2.7.-A Required Thermal Characteristics of Fenestration and Doors


    Notes to Table 9.36.2.7.-A:
    (1) See Note A-Table 9.36.2.7.-A.
    (2) See Article 1.1.3.1.
    (3) Except skylights (see Sentence (2)) and glass block assemblies (see Sentence (4)).

  2. Skylights shall have an overall thermal transmittance not greater than the values listed in Table 9.36.2.7.-B for the applicable heating-degree day category. (See Note A-9.36.2.7.(1) and (2).)


    Table 9.36.2.7.-B
    Overall Thermal Transmittance of Skylights
    Forming Part of Sentence 9.36.2.7.(2)


    Notes to Table 9.36.2.7.-B:
    (1) See Article 1.1.3.1.

  3. 3) Except for site-assembled or site-glazed factory-made fenestration products, curtain wall construction, and site-built windows and glazed doors that are tested in accordance with Sentence 9.36.2.2.(3), site-built windows and glazed doors need not comply with Sentence (1), provided they are constructed in accordance with one of the options presented in Table 9.36.2.7.-C for the applicable climate zone. (See Note A-9.36.2.7.(3).)

    Table 9.36.2.7.-C
    Compliance Options for Site-built Windows and Glazed Portion of Doors
    Forming Part of Sentence 9.36.2.7.(3)

    Table 9.36.2.7.-C Compliance Options for Site-built Windows and Glazed Portion of Doors

  4. Glass block assemblies separating conditioned space from unconditioned space or the exterior shall have
    1. an overall thermal transmittance of not more than 2.9 W/(m2·K), and
    2. a total aggregate area of not more than 1.85 m2.
  5. One door separating a conditioned space from an unconditioned space or the exterior is permitted to have an overall thermal transmittance up to 2.6 W/(m2·K).
  6. Storm windows and doors need not comply with Sentence (1).
  7. Vehicular access doors separating a conditioned space from an unconditioned space or the exterior shall have a nominal thermal resistance of not less than 1.1 (m2·K)/W.
  8. Access hatches separating a conditioned space from an unconditioned space shall be insulated to a nominal thermal resistance of not less than 2.6 (m2·K)/W.
9.36.2.8. Thermal Characteristics of Building Assemblies Below-Grade or in Contact with the Ground
  1. Except as provided in Sentence (2) and Article 9.36.2.5., the effective thermal resistance of building assemblies that are below-grade or in contact with the ground shall be not less than that shown for the applicable heating-degree day category in
    1. Table 9.36.2.8.-A, where the ventilation system does not include heat-recovery equipment, or
    2. Table 9.36.2.8.-B, where the ventilation system includes heat-recovery equipment conforming to Article 9.36.3.9. (See Note A-9.36.2.8.(1).)


      Table 9.36.2.8.-A
      Effective Thermal Resistance of Assemblies Below-Grade or in Contact with the Ground in Buildings without a Heat-Recovery Ventilator
      Forming Part of Sentences 9.36.2.8.(1) to (9)

      Notes to Table 9.36.2.8.-A:
      (1) See Note A-Tables 9.36.2.8.-A and -B.
      (2) See Article 1.1.3.1.
      (3) Does not apply to below-grade floors over heated crawl spaces.
      (4) Typically applies to floors-on-ground in full-height basements.
      (5) Refers to undisturbed frost line before house is constructed.
      (6) See Sentence 9.25.2.3.(5) for requirement on placement of insulation. The design of slabs-on-grade with an integral footing is addressed in Part 4 (see Article 9.16.1.2.).


      Table 9.36.2.8.-B
      Effective Thermal Resistance of Assemblies Below-Grade or in Contact with the Ground in Buildings with a Heat-Recovery Ventilator
      Forming Part of Sentences 9.36.2.8.(1) to (9)

      Table 9.36.2.8.-B Effective Thermal Resistance of Assemblies Below-Grade or in Contact with the Ground in Buildings with a Heat-Recovery Ventilator

      Notes to Table 9.36.2.8.-B:
      (1) See Note A-Tables 9.36.2.8.-A and -B.
      (2) See Article 1.1.3.1.
      (3) Does not apply to below-grade floors over heated crawl spaces.
      (4) Typically applies to floors-on-ground in full-height basements.
      (5) Refers to undisturbed frost line before house is constructed.
      (6) See Sentence 9.25.2.3.(5) for requirement on placement of insulation. The design of slabs-on-grade with an integral footing is addressed in Part 4 (see Article 9.16.1.2.).

  2. Where an entire floor assembly falls into two of the categories listed in Tables 9.36.2.8.-A and 9.36.2.8.-B, the more stringent value shall apply. (See Note A-9.36.2.8.(2).)
  3. Where the top of a section of foundation wall is on average less than 600 mm above the adjoining ground level, the above-ground portion of that section of wall shall be insulated to the effective thermal resistance required in Table 9.36.2.8.-A or 9.36.2.8.-B.
  4. Unheated floors-on-ground that are above the frost line and have no embedded heating pipes, cables or ducts shall be insulated to the effective thermal resistance required in Table 9.36.2.8.-A or 9.36.2.8.-B
    1. on the exterior of the foundation wall down to the footing, or
    2. on the interior of the foundation wall and, as applicable,
      1. beneath the slab for a distance not less than 1.2 m horizontally or vertically down from its perimeter with a thermal break along the edge of the slab that meets at least 50% of the required thermal resistance,
      2. on top of the slab for a distance not less than 1.2 m horizontally from its perimeter, or
      3. within the wooden sleepers below the floor for a distance not less than 1.2 m horizontally from its perimeter. (See Note A-9.36.2.8.(4).)
  5. Except as provided in Sentence (6), floors-on-ground with embedded heating ducts, cables or pipes shall be insulated to the effective thermal resistance required in Table 9.36.2.8.-A or 9.36.2.8.-B under their full bottom surface including the edges.
  6. Where only a portion of a floor-on-ground has embedded heating ducts, cables or pipes, that heated portion shall be insulated to the effective thermal resistance required in Table 9.36.2.8.-A or 9.36.2.8.-B under its full bottom surface to 1.2 m beyond its perimeter including exterior edges if applicable.
  7. In addition to the requirements stated in Sentences (5) and (6), heated floors-on-ground shall be insulated to the effective thermal resistance required in Table 9.36.2.8.-A or 9.36.2.8.-B vertically
    1. around their perimeter, or
    2. on the outside of the foundation wall, extending down to the level of the bottom of the floor.
  8. Floors on permafrost shall be insulated to the effective thermal resistance required in Table 9.36.2.8.-A or 9.36.2.8.-B under the entire slab and around all edges, and under the integral perimeter footing.
  9. Slabs-on-grade with an integral perimeter footing shall
    1. be insulated to the effective thermal resistance required in Table 9.36.2.8.-A or 9.36.2.8.-B under the entire slab and around all edges, but not under the integral perimeter footing, and
    2. be constructed with skirt insulation having the same effective thermal resistance as the insulation installed under the slab. (See Note A-9.36.2.8.(9).) (See also Sentences 9.25.2.3.(5) and 9.36.2.5.(8).)
  10. Junctions between below-grade assemblies shall be protected from the ingress of soil gas in conformance with Subsection 9.25.3.
9.36.2.9. Airtightness
  1. The leakage of air into and out of conditioned spaces shall be controlled by constructing
    1. a continuous air barrier system in accordance with Sentences (2) to (6), Subsection 9.25.3. and Article 9.36.2.10.,
    2. 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
    3. 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
      1. 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
      2. 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
    1. across construction, control and expansion joints,
    2. across junctions between different building materials and assemblies, and
    3. around penetrations through all building assemblies.
  3. Windows, doors and skylights and their components shall comply with the minimum air leakage requirements stated in
    1. AAMA/WDMA/CSA 101/I.S.2/A440, "NAFS - North American Fenestration Standard/Specification for Windows, Doors, and Skylights" (Harmonized Standard), and
    2. 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
    1. compatible with adjoining materials, and
    2. 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
    1. lapped not less than 50 mm,
    2. sealed (see Note A-9.36.2.10.(5)(b)), and
    3. structurally supported.
  6. Sealant material used for the purpose of creating a continuous air barrier system shall
    1. be a non-hardening type, or
    2. conform to
      1. Subsection 9.27.4.,
      2. CAN/ULC-S710.1, "Thermal Insulation - Bead-Applied One Component Polyurethane Air Sealant Foam, Part 1: Material Specification," or
      3. 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
    1. 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
    2. 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
    1. sealing all joints and junctions between the structural components, or
    2. 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:
    1. sealing all joints and junctions between the structural components, or
    2. 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 is on the interior of the building envelope and knee walls that separate conditioned space from unconditioned space shall be constructed airtight by
    1. sealing all junctions between the structural components,
    2. covering the structural components with an air barrier material and sealing it to the adjacent air barrier material, or
    3. 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
    1. sealing the air barrier material to the vent stack pipe with a compatible sealant or sheathing tape, or
    2. 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
    1. sealing all junctions between the structural components, or
    2. 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.
9.36.2.11. Trade-off Options for Above-ground Building Envelope Components and Assemblies
(See Note A-9.36.2.11.)
  1. Subject to the limitations stated in Sentences (6) to (8), the trade-off options described in Sentences (2) to (4) apply only to above-ground building envelope components and assemblies, or portions thereof, of a single building.
  2. The effective thermal resistance of one or more above-ground opaque building envelope assemblies is permitted to be less than that required in Article 9.36.2.6., provided
    1. the total areas of all proposed and reference assemblies are equal,
    2. the effective thermal resistance of one or more other proposed above-ground opaque building envelope assembly areas is increased to more than that required by Article 9.36.2.6., and
    3. the sum of the areas of all traded above-ground opaque building envelope assemblies divided by their respective effective thermal resistance is less than or equal to what it would be if all assemblies complied with Article 9.36.2.6. (See Notes A-9.36.2.11.(2) and A-9.36.2.11.(2) and (3).)
  3. The effective thermal resistance of one or more windows, as calculated in accordance with Sentence (5), is permitted to be less than that required in Article 9.36.2.7., provided
    1. the total areas of all traded windows are equal,
    2. the traded windows are located in the same orientation,
    3. the effective thermal resistance of one or more other windows is increased to more than that required by Article 9.36.2.7., and
    4. the sum of the areas of all traded windows divided by their respective effective thermal resistance is less than or equal to what it would be if all windows complied with Article 9.36.2.7. (See Notes A-9.36.2.11.(3) and A-9.36.2.11.(2) and (3).)
  4. The effective thermal resistance of one or more portions of floor insulation or ceiling insulation in attics under sloped roofs in buildings that are one storey in building height is permitted to be less than that required in Article 9.36.2.6., provided
    1. the total area of fenestration, excluding skylights, and doors does not exceed 15% of the above-ground gross wall area as calculated in accordance with Article 9.36.2.3.,
    2. the floor-to-ceiling height measured from the top of the subfloor to the underside of the finished ceiling of the storey does not exceed 2.34 m,
    3. the distance measured from the top of the subfloor to the underside of the bottom chord of the truss or joist of the roof is not more than 2.39 m, and
    4. the difference between the sum of the proposed areas of ceilings or floors divided by their respective proposed effective thermal resistance and the sum of the reference areas of ceilings or floors divided by their respective thermal resistance required in Article 9.36.2.6. is not more than the difference between 17% fenestration and door area and the proposed fenestration and door areas divided by the required effective thermal resistance values for windows and doors in Article 9.36.2.7. (See Notes A-9.36.2.11.(4) and A-9.36.2.11.(2) and (3).)
  5. The effective thermal resistance of windows shall be determined using one of the following equations, as applicable:
    1. RSI = 1/U, where the U-value is known, or
    2. RSI = 20/(57-ER), where the energy rating is known.
  6. The reduction in effective thermal resistance of above-ground opaque building envelope assemblies permitted by Sentences (2) and (4) shall result in an RSI value that is not less than
    1. 55% of that required in Article 9.36.2.6. for above-ground walls and joist-type roofs (see Note A-9.36.2.11.(6)(a)), and
    2. 60% of that required in Article 9.36.2.6. for other opaque assemblies.
  7. The effective thermal resistances of above-ground opaque assemblies with embedded heating cables, pipes or membranes are not permitted to be traded.
  8. The effective thermal resistances of doors and access hatches described in Sentences 9.36.2.7.(3) to (7) are not permitted to be traded.

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