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Exterior insulation

Driven_5EM | Posted in Energy Efficiency and Durability on

I am considering adding a slightly modified exterior insulation detail my build  coming up. Instead of using Rockwool comfort-board 80 3”, I am considering this assembly from the interior to exterior .1/2” drywall, intello membrane, r22 insulation, 2×6 -24” o/c, plywood , tyvec (wrb/air barrier), 2×4 24”o/c horizontal strapping, r14 rockwool, 1×4 vertical strapping then siding. This only amounts a to about .004% thermal bridge if you don’t strap over bottom and top plates, the cost is less than using comfortboard and you don’t have to mess around trying to get a straight wall. My concern is, am I blocking  drying possibilities by cross strapping? I am interested in comments. climate zone 5 in BC. Thank you.

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Replies

  1. Expert Member
    MALCOLM TAYLOR | | #1

    Marty,

    No worries about drying. That wall assembly will work very well. Consider moving the WRB (Tyvek) to the outside of the horizontal strapping. That will mitigate any worries of moisture accumulating on the top of the 2"x4"s, and will simplify the detailing of flashing at windows , etc.

  2. Driven_5EM | | #2

    Makes sense. Thank you.

    1. Expert Member
      MALCOLM TAYLOR | | #3

      Marty,

      One thing I hadn't thought of: Moving the WRB out does have the advantages I said, but it means it will get penetrated by the siding fasteners when they go though the vertical 1"x4"s. Usually that isn't a problem because the Tyvek is backed by the sheathing, but in your case it will only have the mineral wool behind it.

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