Can the DOW product Perimate be used as an exterior foam insulation and rainscreen in one?
DOW has a Styrofoam product called Perimate, it is a foam sheathing that is typically used in exterior foundation applications in which dovetail grooves allow water to channel out. http://building.dow.com/na/en/products/insulation/perimate.htm. Could this product be used as an exterior sheathing and rain screening in one product? I would apply bug screen at the bottom and use corravent s-400 underneath the freeze board to allow for some air to travel behind the siding. The labor cost of installing foam board plus vertical strapping can be cost prohibitive for some homeowners, and I’m trying to seek alternative methods of exterior insulation to combat thermal bridging and provide some form of drainage and air flow behind siding.
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A while back I asked the same question to our DOW rep. and he said yes, you can use Perimate as WRB. However, depending on the cladding you are using, you may need to install the vertical strapping anyways, and it can get expensive with 2x8 boards. The cladding manufacturer installations instructions should tell you if you need structural strapping or not to be covered for warranty.
I like to spec StuccoWrap over sheathing and then 4x8 sheets of taped Styrofoam over it. The taped StuccoWrap over OSB/Plywood sheathing allows installing windows and doors much easier, minimizing mistakes in moisture management, and it gives a good second moisture barrier; cheap insurance.
Jason,
Here's an article you may be interested in: Using Rigid Foam As a Water-Resistive Barrier.
One problem with your suggestion: Ideally, you want air flow behind your siding to help the back of the siding dry quickly. The Dow Perimate is mostly foam; the drainage slots make up a small percentage of its area. That means that most of your siding will be up against the foam, without much air behind it -- meaning that the siding will dry from only one side.