One option to avoid ember entry into attics is to use and unvented design. An unvented attic is one where vents are intentionally omitted. There are two common features to an unvented attic design. The first is the thermal barrier (i.e., the location of the insulation) is moved from the ceiling plane (between living space and attic) to the roof line (i.e., to the underside of the roof sheathing). Usually closed or open-cell foam insulation is used in unvented attic designs. The second feature is the installation of an air barrier.  With an unvented attic design, the attic becomes a conditioned space (i.e., one that can be heated and cooled). Insulation applied to the bottom of the roof sheathing keeps the attic warm, avoiding temperatures that would lead to moisture condensation. The air barrier minimizes moisture movement.

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