Vapor-Open Membrane for Unvented Attic
Unvented attics that are not insulated with ccSPF have been prescribed a vapor diffusion port to take care of the interior moisture migrating upwards to the sheathing. However, ive seen this used primarily in asphalt roofing (shingles and felt) where that combination provides essentially a vapor barrier above the deck, trapping moisture in the sheathing.
So my thought is that if I have a vapor open membrane (solitex mento, 38 perms) above a plywood roof deck, and have a rain screen with a ridge vent, that would essentially convert my entire roof into vapor diffuser as vapor has nowhere to become trapped. Does this make sense in a hot, humid climate?
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