One option to avoid ember entry into attics is to use an unvented design. An unvented attic is one in which vents are intentionally omitted. It has two common features. The first is that the thermal barrier (i.e., the location of the insulation) is moved from the ceiling between living space and attic to the roofline (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. The air barrier should be where the insulation is. With this 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. An unvented attic is easier to install with new construction but can be a retrofit option for existing homes. Quality installation is always important, but in the case of retrofitting, it is even more so.

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