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Exterior wall system with brick veneer

4NVCHfaoUq | Posted in Energy Efficiency and Durability on

We plan to use 8.5″ wide plates with a 2×6 wall on the exterior edge and a 2×4 wall on the interior edge, staggered to avoid contact with the 2×6 wall. We will spray 6-6.5″ open-cell insulation, use .5″ OSB sheathing and a final exterior layer of .5″ Tuff R, taped.

We are in Charlotte, so ambient moisture is as much of a concern as thermal. Any thoughts?

Also, is polyiso as effective as extruded polystyrene?


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  1. GBA Editor
    Martin Holladay | | #1

    Q. "Any thoughts?"

    A. Your wall assembly sounds fine to me.

    Q. "Is polyiso as effective as extruded polystyrene?"

    A. I'm not sure what type of effectiveness you are talking about. Foil-faced polyiso is an effective vapor barrier, which is a good idea in this case, because you want to stop inward solar vapor drive. If all you are thinking of installing is 1/2-inch rigid foam (as opposed to a thicker layer), then foil-faced polyiso is a more effective vapor barrier than XPS. When it comes to R-value, polyiso has a slightly higher R-value per inch than XPS.

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