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Does the roof sheathing side in the attic space have to be insulated?

C D | Posted in Building Code Questions on

in some rooms in the upper levels there is attic space with an access door. I realize that the walls which are against the liveable space have to be insulated, but does the side with the roof sheathing have to be insulated? This is the side where the roof shingles are attached.

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  1. GBA Editor
    Martin Holladay | | #1

    Every house needs a well-defined thermal boundary. In most homes, the attic is outside of this thermal boundary. If that's the case at your house, you have what is called a vented unconditioned attic.

    In a few houses, the attic is inside the home's thermal boundary. If you have that kind of house, the attic is called an unvented conditioned attic.

    In either case -- whether you have a vented unconditioned attic or an unvented conditioned attic -- you need to know where your thermal boundary is. The thermal boundary should be uninterrupted; as airtight as possible; and should include a layer of insulation in direct contact with the air barrier.

    For more information, see this article: Creating a Conditioned Attic.

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