Tempo:
Electrical and mechanical features such as boxes, pipes and ducts should not be installed in exterior walls. Where this cannot be avoided, the NBC allows slightly reduced insulation levels at these locations provided the plane of insulation is continuous. Air barrier continuity at these penetrations is still important. Small spaces at intersections in corners and around openings must contain insulation that is not compressed. Walls between dwelling units and garages must be insulated to the same level as exterior walls, whether the garage is heated or not, because garages may be left open for extended periods of time.
Floors over Unconditioned Spaces Floors over unheated crawl spaces or over garages must be insulated. It is common to fill the space between the floor sheathing and a gypsum board ceiling under the floor with insulation.
Where there is no finished ceiling on the underside of the floor, the insulation must be supported (to prevent the insulation from falling through). For friction-fit batts or rigid insulation (Figure 23), attach wire lath, “chicken wire”, wood furring or a vapour permeable sheet material to the bottom of the joists. For loose fill-type insulation, provide solid support with a vapour-permeable material (to avoid creating a vapour barrier on the cold side of the insulation). Fit insulation around cross-bridging or blocking between joists and insulate small spaces such as those between blocked double joists or joist spaces below a wall. The NBC requires that a vapour barrier be installed on the warm side of the insulation, which is usually the upper side in a floor over an unconditioned space. A plywood or OSB subfloor with tight-fitting or sealed joints can serve as the vapour barrier.
23 Floor over unheated crawl space insulated with friction-fit batts
finish flooring polyethylene vapour barrier friction fit or loose fill insulation wood floor joists vapour-permeable air barrier material wire lath (or other suitable material)
Floors over Unconditioned Spaces Floors over unheated crawl spaces or over garages must be insulated. It is common to fill the space between the floor sheathing and a gypsum board ceiling under the floor with insulation.
Where there is no finished ceiling on the underside of the floor, the insulation must be supported (to prevent the insulation from falling through). For friction-fit batts or rigid insulation (Figure 23), attach wire lath, “chicken wire”, wood furring or a vapour permeable sheet material to the bottom of the joists. For loose fill-type insulation, provide solid support with a vapour-permeable material (to avoid creating a vapour barrier on the cold side of the insulation). Fit insulation around cross-bridging or blocking between joists and insulate small spaces such as those between blocked double joists or joist spaces below a wall. The NBC requires that a vapour barrier be installed on the warm side of the insulation, which is usually the upper side in a floor over an unconditioned space. A plywood or OSB subfloor with tight-fitting or sealed joints can serve as the vapour barrier.
23 Floor over unheated crawl space insulated with friction-fit batts
finish flooring polyethylene vapour barrier friction fit or loose fill insulation wood floor joists vapour-permeable air barrier material wire lath (or other suitable material)
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