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Help with vapour barrier in cold climate
I'm adding a partition wall in my house and I'm looking for advice about adding or not a vapour barrier in the ceiling/roof/. Most of the house is from 1949 but this section was built late 60's/early 70's in Quebec, Canada for reference (HDD18 4700, cold and dry winter, humid and warm summer). The wall is parallel to the ceiling joists, which is a flat roof above, so I'm adding blocking as per code to tie my wall into. There is 6" of paper backed insulation in the 2x10" joist bay, with an air gap of about 4 in above but as far as I can tell, the flat roof isn't ventilated. There are no exit air vents on top of it and I've extended my camera down to the edge of a joist bay from the inside and couldn't see any light coming from the soffit. So I'm somewhat confident there is no ventilation in the roof. The code here calls for a 6mil polyethylene vapour barrier to be added in the warm side of the insulation but the code also calls for an air tight enveloppe around the exterior of the house which I'm very doubtful I have. I've added a picture of the current setup, from the inside it goes : 1/2'' drywall, 3/4 strapping, 1/2'' whatever the hell this cardboard looking panel is, fairly continuous Kraft? paper barrier under the joists and on the insulation, 6" paper backed insulation, air gap and finally the roof panels. Everything looks healthy up there and the 6 mil poly vs the current kraft paper interact fairly differently with vapour so I'm hesitant to install it. Also, where would it go? I'm having a hard time removing the fiberboard thing without damaging the kraft paper so I can overlap the poly sheet (code is 4 in overlap if I remember correctly). What's the purpose of the fiberboard in all this? Do I reinstall a layer once the wall is framed? Would rigid insulation in that joist bay solve any of my issues? Your help is much appreciated. Thanks submitted by /u/captain_fuck_you [link] [comments]
| | I'm adding a partition wall in my house and I'm looking for advice about adding or not a vapour barrier in the ceiling/roof/. Most of the house is from 1949 but this section was built late 60's/early 70's in Quebec, Canada for reference (HDD18 4700, cold and dry winter, humid and warm summer). The wall is parallel to the ceiling joists, which is a flat roof above, so I'm adding blocking as per code to tie my wall into. There is 6" of paper backed insulation in the 2x10" joist bay, with an air gap of about 4 in above but as far as I can tell, the flat roof isn't ventilated. There are no exit air vents on top of it and I've extended my camera down to the edge of a joist bay from the inside and couldn't see any light coming from the soffit. So I'm somewhat confident there is no ventilation in the roof. The code here calls for a 6mil polyethylene vapour barrier to be added in the warm side of the insulation but the code also calls for an air tight enveloppe around the exterior of the house which I'm very doubtful I have. I've added a picture of the current setup, from the inside it goes : 1/2'' drywall, 3/4 strapping, 1/2'' whatever the hell this cardboard looking panel is, fairly continuous Kraft? paper barrier under the joists and on the insulation, 6" paper backed insulation, air gap and finally the roof panels. Everything looks healthy up there and the 6 mil poly vs the current kraft paper interact fairly differently with vapour so I'm hesitant to install it. Also, where would it go? I'm having a hard time removing the fiberboard thing without damaging the kraft paper so I can overlap the poly sheet (code is 4 in overlap if I remember correctly). What's the purpose of the fiberboard in all this? Do I reinstall a layer once the wall is framed? Would rigid insulation in that joist bay solve any of my issues? Your help is much appreciated. Thanks [link] [comments] |
