9.25.

(1) This Section applies to the application of thermal insulation and measures to control condensation, heat transfer and air leakage for buildings of residential occupancy intended for use on a continuing basis during the winter months.

(2) Insulation and sealing of heating and ventilating ducts shall conform to Sections 9.32. and 9.33.

(1) Sheet and panel-type materials shall be installed in accordance with Sentence (2), if the material,

(a) has an air leakage characteristic less than 0.1 L/(s∙m²) at 75 Pa,

(b) has a water vapour permeance less than 60 ng/(Pa∙s∙m²) when measured in accordance with ASTM E96, “Water Vapor Transmission of Materials”, using the desiccant method (dry cup), and

(c) is incorporated into a building assembly required by Article 9.25.2.1. to be insulated.

(2) Sheet and panel-type material described in Sentence (1) shall be installed,

(a) on the warm face of the assembly,

(b) except as provided in Sentences (3) to (5), at a location where the ratio between the total thermal resistance of all materials outboard of its innermost impermeable surface and the total thermal resistance of all materials inboard of that surface is not less than that required in Table 9.25.1.2., or

(c) outboard of an air space that is vented to the outdoors and, for walls, drained.

(3) Wood-based sheathing materials not more than 12.5 mm thick and complying with Article 9.23.16.2.v1 need not comply with Sentence (1).

(4) Where the mild climate indicator, determined in accordance with Sentence (6), is greater than 6300, the position of low air- and vapour-permeance materials within the assembly relative to the position of materials providing thermal resistance shall be determined according to Part 5 where,

(a) the intended use of the interior space requires the indoor relative humidity to be maintained above 35% over the heating season and the ventilating and air-conditioning system is designed to maintain that relative humidity, or

(b) the intended use of the interior space will result in an indoor relative humidity above 35% over the heating season and the ventilating and air-conditioning system does not have the capacity to reduce the relative humidity to 35% for any period over that period.

(5) Where the mild climate indicator, determined in accordance with Sentence (6), is less than or equal to 6300, the position of low air- and vapour-permeance materials within the assembly relative to the position of materials providing thermal resistance shall be determined according to Part 5 where,

(a) the intended use of the interior space requires the indoor relative humidity to be maintained above 60% over the heating season and the ventilation and air-conditioning system is designed to maintain that relative humidity, or

(b) the intended use of the interior space will result in an indoor relative humidity above 60% over the heating season and the ventilating and air-conditioning system does not have the capacity to reduce the relative humidity above 60% for any period over that period.

(6) The mild climate indicator (MCI) shall be calculated according to the following formula:

MCI = abs(2.5% JMT) ∙ 200 + DD

where,

abs(2.5% JMT) = absolute value of 2.5% January mean temperature, and

DD = degree-days

(7) For walls, the air space described in Clause (2)(c) shall comply with Clause 9.27.2.2.(1)(a).

(1) All walls, ceilings and floors separating heated space from unheated space, the exterior air or the exterior soil shall be provided with thermal insulation in conformance with Sections 12.2. and 12.3. to prevent moisture condensation on their room side during the winter and to ensure comfortable conditions for the occupants.

(1) Except as required in Sentence (2), thermal insulation shall conform to the requirements of,

(a) CAN/CGSB-51.25-M, “Thermal Insulation, Phenolic, Faced”,

(b) CAN/CGSB-51-GP-27M, “Thermal Insulation, Polystyrene, Loose Fill”,

(c) CAN/ULC-S701, “Thermal Insulation, Polystyrene, Boards and Pipe Covering”,

(d) CAN/ULC-S702 “Mineral Fibre Thermal Insulation for Buildings”,

(e) CAN/ULC-S703, “Cellulose Fibre Insulation (CFI) for Buildings”,

(f) CAN/ULC-S704, “Thermal Insulation, Polyurethane and Polyisocyanurate, Boards, Faced”,

(g) CAN/ULC-S705.1, “Thermal Insulation – Spray Applied Rigid Polyurethane Foam, Medium Density – Material Specification”, or

(h) CAN/ULC-S706, “Wood Fibre Thermal Insulation for Buildings”.

(2) The flame-spread rating requirements contained in the standards listed in Sentence (1) shall not apply.

(3) Insulation in contact with the ground shall be inert to the action of soil and water and be such that its insulative properties are not significantly reduced by moisture.

(4) Type 1 expanded polystyrene insulation as described in CAN/ULC-S701, “Thermal Insulation, Polystyrene, Boards and Pipe Covering”, shall not be used as roof insulation applied above the roofing membrane.

(1) Insulation shall be installed so that there is a reasonably uniform insulating value over the entire face of the insulated area.

(2) Insulation shall be applied to the full width and length of the space between furring or framing.

(3) Except where the insulation provides the principal resistance to air leakage, thermal insulation shall be installed so that at least 1 face is in full and continuous contact with an element with low air permeance.

(4) Insulation on the interior of foundation walls enclosing a crawl space shall be applied so that there is not less than a 50 mm clearance above the crawl space floor if the insulation is of a type that may be damaged by water.

(5) Insulation around concrete slabs-on-ground shall be located so that heat from the building is not restricted from reaching the ground beneath the perimeter, where exterior walls are not supported by footings extending below frost level.

(6) Where insulation is exposed to the weather and subject to mechanical damage, it shall be protected with not less than,

(a) 6 mm asbestos-cement board,

(b) 6 mm preservative-treated plywood, or

(c) 12 mm cement parging on wire lath applied to the exposed face and edge.

(7) Except as permitted in Sentence (8) insulation and vapour barrier shall be protected from mechanical damage by a covering such as gypsum board, plywood, particleboard, OSB, waferboard or hardboard.

(8) In unfinished basements, the protection required in Sentence (7) need not be provided for mineral fibre insulation provided it is covered with polyethylene vapour barrier of at least 0.15 mm in thickness.

(9) Insulation in factory-built buildings shall be installed so that it will not become dislodged during transportation.

(1) Except as provided in Sentences (2) to (5), loose-fill insulation shall be used on horizontal surfaces only.

(2) Where loose-fill insulation is installed in an unconfined sloped space, such as an attic space over a sloped ceiling, the supporting slope shall not be more than,

(a) 4.5 in 12 for mineral fibre or cellulose fibre insulation, and

(b) 2.5 in 12 for other types of insulation.

(3) Loose-fill insulation may be used in wood-frame walls of existing buildings.

(4) Where blown-in insulation is installed in above-ground or below-ground wood frame walls of new buildings,

(a) the density of the installed insulation shall be sufficient to preclude settlement,

(b) the insulation shall be installed behind a membrane that will permit visual inspection prior to installation of the interior finish,

(c) the insulation shall be installed in a manner that will not interfere with the installation of the interior finish, and

(d) no water shall be added to the insulation, unless it can be shown that the added water will not adversely affect other materials in the assembly.

(5) Water repellent loose-fill insulation may be used between the outer and inner wythes of masonry cavity walls.

(6) Where soffit venting is used, measures shall be taken,

(a) to prevent loose-fill insulation from blocking the soffit vents and to maintain an open path for circulation of air from the vents into the attic or roof space, and

(b) to minimize air flow into the loose-fill insulation near the soffit vents to maintain the thermal performance of the material.

(1) Spray-applied polyurethane insulation shall be installed in accordance with CAN/ULC-S705.2, “Thermal Insulation – Spray-Applied Rigid Polyurethane Foam, Medium Density, Installer’s Responsibilities – Specification”.

(1) Thermally insulated wall, ceiling and floor assemblies shall be constructed so as to include an air barrier system that will provide a continuous barrier to air leakage,

(a) 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

(b) from the exterior inward sufficient to prevent moisture condensation on the room side during winter.

(1) Sheet and panel type 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 differential of 75 Pa.

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

(1) Where the air barrier system consists of an air-impermeable panel-type material, all joints shall be sealed to prevent air leakage.

(2) Where the air barrier system consists of flexible sheet material, all joints shall be,

(a) sealed, or

(b) 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 an air barrier protection, the air barrier system shall extend across the intersection.

(4) 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.

(5) 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.

(6) 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.

(7) Access hatches installed through assemblies constructed with an air barrier system shall be weatherstripped around their perimeters to prevent air leakage.

(8) 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.

(1) Thermally insulated wall, ceiling and floor assemblies shall be constructed with a vapour barrier sufficient to prevent condensation in the wall spaces, floor spaces or attic or roof spaces.

(1) Vapour barriers shall have a permeance not greater than 60 ng/(Pa∙s∙m²), measured in accordance with ASTM E96, “Water Vapor Transmission of Materials”, using the desiccant method (dry cup).

(2) Where the mild climate indicator, determined in accordance with Sentence 9.25.1.2.(6)v1, is greater than 6300, vapour barriers shall be designed according to Part 5, where,

(a) the intended use of the interior space requires the indoor relative humidity to be maintained above 35% over the heating season and the ventilating and air-conditioning system is designed to maintain that relative humidity, or

(b) the intended use of the interior space results in an average monthly indoor relative humidity above 35% over the heating season and the ventilating and air-conditioning system does not have the capacity to reduce the average monthly relative humidity to 35% or less over that period.

(3) Where the mild climate indicator, determined in accordance with Sentence 9.25.1.2.(6)v1, is less than or equal to 6300, vapour barriers shall be designed according to Part 5, where,

(a) the intended use of the interior space requires the indoor relative humidity to be maintained above 60% over the heating season and the ventilating and air-conditioning system is designed to maintain that relative humidity, or

(b) the intended use of the interior space results in an average monthly indoor relative humidity above 60% over the heating season and the ventilating and air-conditioning system does not have the capacity to reduce the average monthly relative humidity to 60% over that period.

(4) Where polyethylene is installed to serve as the vapour barrier, it shall conform to CAN/CGSB-51.34-M, “Vapour Barrier, Polyethylene Sheet for Use in Building Construction”.

(5) Membrane-type vapour barriers other than polyethylene shall conform to CAN/CGSB-51.33-M, “Vapour Barrier, Sheet, Excluding Polyethylene, for Use in Building Construction”.

(6) Where a coating is applied to gypsum board to function as the vapour barrier, the permeance of the coating shall be determined in accordance with CAN/CGSB-1.501-M, “Method for Permeance of Coated Wallboard”.

(1) Vapour barriers shall be installed to protect the entire surfaces of thermally insulated wall, ceiling and floor assemblies.

(2) Vapour barriers shall be installed sufficiently close to the warm side of insulation to prevent condensation at design conditions.