Critique my cathedral roof insulation (Part 2)
You might have saw my earlier thread. Here it is:
A friend recommended I make a slight adjustment in order bring down costs a bit.
For price reference:
- 32 sq. ft. @ 2" of XPS (pink foam) is - $51 a sheet. (for R-20 that's $100 (2"x2))
- 100 sq. ft. of fiber batt is $90. (R-22, i think)
Anyway here is the secondary design. I really apologize for the awfully crewed drawings but I couldn't find much other way to do it.
The idea is to put 1" of XPS (while maintaining at least 2" of airspace between roof deck and XPS..I have adequate softet vents ) above a layer of fiber batt (down to the ceiling joist). I will caulk/sprayfoam where the XPS meets the wood to airseal. Below the ceiling joist will go 4.5" of poly iso. Polyiso will be air sealed at all joints (so no air barrier will be needed below polyiso). Followed by OSB or drywall. I may put tung and groove back or stick w/ drywall..not sure.
This design saves me quite a bit of money while providing similar R-value.
Questions I have...
- Will this design work? I figure I will make every precaution to install fiber batt properly.
- Can I use a 1/2" of XPS on the top. I have quite a bit of insulation below so I don't think I will have condensation issues.
- Any critiques are great. Thanks a lot everyone!
Posted Sun, 03/03/2013 - 14:24
Edited Mon, 03/04/2013 - 11:14
Other Questions in Plans Review