When it comes to sheathing a roof with CDX (particle board), does it matter which side of the sheathing is facing up? It seems like since it will be covered with a layer of roofing felt and then shingles it shouldn’t matter but why not get the straight dope.
if you mean OSB wafer board, I usually put the rougher side up since it makes for better traction while decking, felting, etc…
if you mean CDX (which imo is plywood and not particle board) I’d put the better side up for smoothness under the felt.
I agree that the rougher side would offer better traction, but the smoother side is better to shed any water, should you get any type of failure in the roofing, and certainly gives better protection should you run into any rain while roofing!
Daizy
The folks that make AdvanTech sheathing www.huberwood.com said on their web site to install with the rougher side up for traction during installation.
Depending on where you live, you might want to look at Cool-Ply (I think that’s the brand name). It has a reflective coating applied to one side (the attic side). It will reduce your cooling load on sunny days by reflecting IR out of the attic space. It’s more expensive, though, than regular OSB.