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Does my ICF foundation require additional protection or barriers applied before backfill?

Chuck Jensen | Posted in General Questions on

In my case the house is located in southwest Colorado at 6900′ elev. on a sunny south slope. The soil is moderately expansive clay so the foundation is 48″ on top of the footer on top of 12″ compacted structural fill. Footer perimeter drain ( smooth pipe in gravel bedding) all around, ground will slope 1:10 away from foundation to a french drain system, and ground gutters or sub-grade pond liner will be installed on the north side to keep bulk water away from the foundation, so good drainage and water control. I’m not sure that free drainiing back fill or a drainage layer is appropriate in this case and that compacted clay backfill would be better to seal water out. It also doesn’t make sense to me to apply peel and stick bituminous sheet because it would inhibit the vapor permeance of the ICF. Also important to note is that this area is low termite infestation. So my question is – can I just drape a WRB layer of house wrap like Tyvek over the entire foundation wall inside and out and the backfill it or would the Tyvek deteriorate in the ground?

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  1. GBA Editor
    Martin Holladay | | #1

    Two quick thoughts:

    1. Rather than relying on the opinions of GBA readers, you should consult the manufacturer of the ICFs you are using. All building codes require all building materials to be installed according to manufacturers' recommendations.

    2. You wrote, "It also doesn't make sense to me to apply peel and stick bituminous sheet because it would inhibit the vapor permeance of the ICF." In fact, you can't expect below-grade ICF walls to dry to the exterior. (An argument could be made that you might want the above-grade portion of this wall to dry to the exterior, however.) Soil tends to be damp, so a layer of peel-and-stick on the exterior side of your ICF wall makes excellent sense below grade.

  2. Jesse Lizer | | #2

    I installed a dimpled plastic drainage plane over my ICF foundation. I did not use a peel and stick. I specifically used Platon. I also had Form-a Drain foundation forms.

    I ran this to the top of my footer. The top of the floor line is actually 6" above the top of the footer (2" of XPS + 4" of slab). The bottom of the platon and form a drain are covered in rock with landscape fabric over it. The reason I chose this product is because its easy to install on ICF (just screw to the plastic) and also removes hydrostatic pressure on the foundation. The foam on the ICF helps to do that already.

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