Cape needs insulation retrofit (with ventilation)
New owner of a 1 1/2 level cape here. Finished upstairs. Zone 5. I'm experienced with home renovations and DIY, but new to Capes.
Trying to bring upstairs environmentals in line with lower level conditioned home temps year round without running the mechanicals 24 /7.
No insulation to speak of. No ventilation. No vapor barrier. Planning to make the attic "outside space".
I've blocked all of the underfloor joist bays, sealed all chases and penetrations, insulated the kneewall hatches very well, etc. This has helped a lot.
Add 60/40 - soffit / ridge venting to a 1:150 target
Add as much cellulose insulation possible on the attic floors (target R40)
Add baffles from the soffits with wind wash protection.
Add as much cellulose (netted) or fiberglass batts (faced) on the backsides of the kneewalls with an air (not vapor) barrier on the backside (target R 15).
This is pretty close to what I'm dealing with: http://www.doityourself.com/forum/attachments/insulation-radiant-vapor-b...
Here's where I'm trying to go:
I'm having trouble determining the best way to insulate the sloped 45 degree walls WHILE maintaining airflow over the insulation.
I'm aware that I should be trying to maintain about 2" of space above the insulation.. but this is a retrofit, so my options are few.
I feel like I have a few options for the 60" long sloped walls from the top of the kneewall to the flat ceiling:
1) install faced fiberglass insulation that fits in the 2 x 6 cavity with 2" of room to spare above.
2) install Rigid foam against that fits between the rafters in the 2 x 6 cavity (directly against the sheetrock).
3) construct my own "baffles" for the sloped walls from rigid 3/4 foam, furr them off the underside of the deck by 2" for airflow and dense pack cellulose below the foam and above the sheetrock.
Any advice or opinions would be greatly appreciated.. as I am struggling with what direction to take here..
Posted Wed, 08/27/2014 - 22:33
Edited Thu, 08/28/2014 - 05:53
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