Condensation under metal roofing
If it is common for condensation to form under metal roofing, and it is also common to NOT flash or waterproof any penetrations at the roof deck level (before roofing is installed), how can one be certain no amount of moisture/condensation is going into the hole cut out for a vent pipe underneath the roofing?
When I do my roof, I plan to cut out a piece of ice and water shield to fit over my pipes (see picture) but even this isn’t water tight probably, unless perhaps there’s caulking around the joint where the ABS (or other penetration) and ice and water shield meet… even then that’s going to fail eventually or not stick at all (the sealant), especially in the case of a polypropylene face of an ice and water shield.
Roofers in my area don’t worry about this, at least of the roofers I’ve talked to. They say they just put the decktite/roof pipe flashing over the pope and seal it to the metal roof. Nothing more, nothing at the deck/sheathing level.
Am I wrong to be concerned about all this? I’m in zone 4c and have a vented system, soffit to ridge. No insulation in the rafters just insulation filling the ceiling joist bays.
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