
If you use strapping rather than solid decking, the strapping must be horizontal and spaced per manufacturer recommendations. The panels will not be walkable if installed on vertical strapping, and other problems such as with snow load could occur as well. One option is to cross-batten. Vertical battens first to create your airflow channels followed by horizontal battens for fastening the roof. Of course, this raises the roof level significantly which can be an issue for gutters, drip edges, dormer windows, sidewall intersections, etc.
I am planning an install of snap-lock standing seam. Its down to a couple different brands/models, but all are 16" wide panels. I have always seen strapping, if added, horizontal below the metal. Is there a reason that strapping shouldn't be oriented vertically, 16" OC? With a vapor-open underlayment it could then act as both the roof venting and attachment for the metal without a second strapping layer.
Of course! Supporting the flexing panel...should have occurred to me.
Thank you so much.