After reading another thread on BuildHub I get the impression there is a regional split between manufacturing roof trusses with treated wood or not. Mine are untreated so I am thinking about applying a coat of preservative before felting, perhaps just the rafter tails that will support the wooden boxed eaves.   Is there a dependable wood preservative brand? They all seem like a variation of snake oil potion to me.   So far I have concluded the best wood preservatives include