[Greenbuilding] R12 for 3" of Roxul Comfortboard IS...

[John Straube]

R15 is a reasonable estimate for a 2x6 wall with R22 batts, drywall and OSB
2X3" = 6" or rockwool, which is about R4/in= 24
15+24=R39

I find the IS and CIS products very dense, and somewhat too rigid and heavy.  Might be good for some, but I prefer to work with lower density products (and they use less material)
I have done 4" or CavityRock Dual Density (DD) on a recent project, as a single lift of 4" (R16.8) and as inner layer for a 5.5" thick assembly
The outer face is high density, like IS, and so stiff and abuse resistant, but the body of the product is flexible, and more accomodating.

Best way to decide is a small mock up.


John Straube | Ph.D, P.Eng.
Associate Professor
Civil and Environmental Engineering / School of Architecture
University of Waterloo
CPH-2373H

-----Original Message-----
From: Greenbuilding [mailto:greenbuilding-bounces at lists.bioenergylists.org] On Behalf Of Nick Pine
Sent: April 29, 2016 16:56
To: greenbuilding at lists.bioenergylists.org
Subject: [Greenbuilding] R12 for 3" of Roxul Comfortboard IS...

Stephen Collette <stephen at yourhealthyhouse.ca> wrote:

>I?d recommend Roxul Comfortboard IS for outboard of the sheathing. I 
>used it myself last year, and it?s excellent, and with 2 3? rigid 
>boards, you can get to the R-40 range easy enough.

How do you get to R40?

Nick
. 


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