‘Finishing’ above-grade Roxul Comfortboard: What are the best practices?
I’m building a new home. The exterior of the home, from the bottom of the basement to the edge of the roofline, is covered in 2″ Roxul Comfortboard.
90% of the Roxul will be covered by Hardi lap siding, however, there’s a gap where the Roxul is not covered. That gap is between the ground level and the top of the foundation wall. Now there are solutions to this problem. For instance, Roxul recommends using cement board to cover the exposed Roxul. But Roxul makes no recommendations on exactly which cement board to install, makes no recommendations on how to fasten the cement board through the Roxul and to the CMUS, and make no recommendations on how to seal the cement board.
It’s easy for Roxul to say, which they have, that all of the above problems can be answered by the manufacturers of the cement board. But when I call Hardi or Durock, both of them have issues with this particular application. Hardi says to absolutely not do what Roxul recommends. And Durock, only warranties their product when attached to furring strips.
With all that said, my questions are below:
– What type of cement board is appropritae to cover Roxul Comfortboard?
– How should the cement board be attached, through the Roxul, and to the Foundation wall?
– How should the cement board be finished and/or water sealed?
Thanks in advance!
GBA Detail Library
A collection of one thousand construction details organized by climate and house part