Roofing Fasteners and Condensation
I am getting ready to order roofing materials for a low-slope and a gable roof. The low-slope roof will have tapered Polyiso, cover board and then TPO. The gable roof will have a top-vented Polyiso nail base panel. In each case, my exterior de-rated Polyiso insulation r-value to total r-value will be greater than the minimum required for my climate zone (4). The insulation on the interior side of the roof deck will be dense-packed cellulose. I will be using #14 roofing fasteners on the low-slope and SIPTP fasteners on the gable roof. Based on the nailing pattern required by the cover board and nail base manufacturers, most of the fasteners will miss the joists and will be penetrating through the deck at least 1″. Should I be concerned about the potential for these cold fasteners to cause condensation to form where they penetrate the underside of the roof sheathing (Advantech on low-slope and Zip on gable roof)?
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