I am installing 1/2" Advantech sheathing on a garage wall, and when I got it home I noticed it has one shiny side and one with a rough pattern imprinted. When I went back to the lumberyard, they could not agree if the shiny side should be to the weather to aid water runoff, or if the rough side goes out to give better traction on roofs! Advantech is closed today (Sun.) and I can't find anything on the website. I've got free help coming this afternoon and was hoping to put them to work! Anybody know which way it goes? Thanks.