My guestion is about a simple gable roof 46 ft long ridge and 17 ft gables. It now has worn shingles and I want to install a metal roof. My head is spinning because contractors are giving me conflicting advise. I have self determined by reading previous post that the old shingles have to go. My guestion is should I use vertical strapping over trusses and horizontal in between? What should go over the plywood decking before strapping? What metal roofing should I use? One with a exposed fastener or one without?And what thickness? I'm in a pretty cold climate with significant snowfalls. Pitch on roof is 3/12. It has a ridge vent and good ventilation. Thank you and looking forward to your reply.