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Community and Q&A

Insulating over an open porch?

SLCtinman | Posted in General Questions on

I have a client building an 12×16 addition to an existing house. The addition will include an open porch/patio which is covered by trusses that span from outside edge of addition to outside edge of porch/patio. The question is this: is it better/cheaper to just insulate & seal the entire attic space between trusses or to create a wall between trusses that separates space above living space & space above porch – and thus only insulating this wall and the attic floor?

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  1. GBA Editor
    Martin Holladay | | #1

    It hardly matters where the insulation goes, as long as the insulation is continuous around your conditioned space.

    A far more important question is: Are you sure you have a continuous air barrier around your conditioned space? This type of porch / attic connection is a notorious example that often results in an interruption of the air barrier.

    Know what materials form your air barrier; be sure it is continuous where your insulated wall meets your insulated ceiling; and check the details at the wall / ceiling junction.

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