Tempo:
Loose-Fill Insulation
Amount of Insulation
Loose-fill insulation is made of materials such as cellulose fibre and mineral wool fibre and is installed by pouring or blowing it into spaces between the framing. In attics, the loose fill extends above the top of the ceiling joists to raise the insulating level and reduce thermal bridging caused by the framing members. Loose fill insulation in walls must be installed behind a membrane that permits visual inspection to ensure there are no gaps or voids before the interior finish is applied.
The NBC (9.36) has requirements for minimum effective levels of thermal insulation for houses. Compliance can be assured by following prescriptive requirements, or by demonstrating that the calculated performance meets or exceeds the performance of a reference house. For buildings other than housing and small buildings, the insulation requirements are contained in the National Energy Code for Buildings.
Rigid Insulation Rigid insulation is manufactured in sheets or boards using materials such as polyisocyanurate and expanded or extruded foamed plastic and is usually applied to flat surfaces such as walls. Extruded polystyrene has low moisture permeability and can be used in damp conditions such as on below-grade walls.
Semi-rigid Insulation Semi-rigid insulation boards are made of glass or mineral fibres and usually applied to flat surfaces such as walls. They are more flexible than rigid insulation products and not as easily damaged by impact or bending. Some semi-rigid insulation has good drainage properties and can be used on below-grade walls.
Foamed-in-place Insulation Specially formulated polyurethane and isocyanurate insulations can be installed by spraying or injecting under pressure. The liquid sets into a rigid mass within minutes of installation. Some products develop heat or expand during the curing process. Ensure that the products being installed are approved for use in houses, and have a qualified contractor perform the installation under well-ventilated conditions.
The prescribed amount of insulation is based on climate severity as determined by heating degree-days (HDDs). The HDD value is the cumulative sum of the differences between 18°C (64°F) and the mean temperature for every hour of every day in the year when the mean temperature is below 18°C (64°F) (NBC Appendix C). As shown in Tables 11 to 13 (pp. 272-274), the NBC prescribes minimum insulation values for each part of the building envelope depending on climate zone. Compliance can also be demonstrated by modeling the proposed house and showing that it uses no more energy than a similar “reference” house that meets the prescribed minimum requirements in the building code. All walls, floors and ceilings that separate heated space from unheated space or the outside air must be insulated to at least the levels required in the NBC for those locations, unless the house is intended for seasonal use only. Trade-offs are permitted between some building assemblies. For example, the thermal resistance of a wall could be less than the minimum required if additional insulation is provided elsewhere, so that the overall insulation value is maintained on an area-weighted average basis.
Amount of Insulation
Loose-fill insulation is made of materials such as cellulose fibre and mineral wool fibre and is installed by pouring or blowing it into spaces between the framing. In attics, the loose fill extends above the top of the ceiling joists to raise the insulating level and reduce thermal bridging caused by the framing members. Loose fill insulation in walls must be installed behind a membrane that permits visual inspection to ensure there are no gaps or voids before the interior finish is applied.
The NBC (9.36) has requirements for minimum effective levels of thermal insulation for houses. Compliance can be assured by following prescriptive requirements, or by demonstrating that the calculated performance meets or exceeds the performance of a reference house. For buildings other than housing and small buildings, the insulation requirements are contained in the National Energy Code for Buildings.
Rigid Insulation Rigid insulation is manufactured in sheets or boards using materials such as polyisocyanurate and expanded or extruded foamed plastic and is usually applied to flat surfaces such as walls. Extruded polystyrene has low moisture permeability and can be used in damp conditions such as on below-grade walls.
Semi-rigid Insulation Semi-rigid insulation boards are made of glass or mineral fibres and usually applied to flat surfaces such as walls. They are more flexible than rigid insulation products and not as easily damaged by impact or bending. Some semi-rigid insulation has good drainage properties and can be used on below-grade walls.
Foamed-in-place Insulation Specially formulated polyurethane and isocyanurate insulations can be installed by spraying or injecting under pressure. The liquid sets into a rigid mass within minutes of installation. Some products develop heat or expand during the curing process. Ensure that the products being installed are approved for use in houses, and have a qualified contractor perform the installation under well-ventilated conditions.
The prescribed amount of insulation is based on climate severity as determined by heating degree-days (HDDs). The HDD value is the cumulative sum of the differences between 18°C (64°F) and the mean temperature for every hour of every day in the year when the mean temperature is below 18°C (64°F) (NBC Appendix C). As shown in Tables 11 to 13 (pp. 272-274), the NBC prescribes minimum insulation values for each part of the building envelope depending on climate zone. Compliance can also be demonstrated by modeling the proposed house and showing that it uses no more energy than a similar “reference” house that meets the prescribed minimum requirements in the building code. All walls, floors and ceilings that separate heated space from unheated space or the outside air must be insulated to at least the levels required in the NBC for those locations, unless the house is intended for seasonal use only. Trade-offs are permitted between some building assemblies. For example, the thermal resistance of a wall could be less than the minimum required if additional insulation is provided elsewhere, so that the overall insulation value is maintained on an area-weighted average basis.
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