Yes, chord size is highly dependant on the span and design load. Trusses I set last week are 28' span, 2x6 chords and 2x4 webs.For you guys in snow country and running trusses, what are your bottom cords on the trusses?
I have very minimal personal experience with spray foam so far, but isn't that one way to get by without venting a roof? I think the foam only counts as a thermal break, so you would still need moisture barrier.
In that picture from the OP, I wonder if there is just condensation on the interior surface that has "wicked" onto the beam?