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Potential problems regarding the use of ZIP System's new R-sheathing?

Does anyone see any potential problems using ZIP System's new R-Sheathing? The product comes in either 1/2" or 1" polyiso on the back of the sheathing between the sheathing and the studs. http://www.zipsystem.com/zip-system/rsheat.aspx.

Once again I am trying to figure out less costly ways to combat thermal bridging, create an air seal, and provide a rainscreen. I would be using the product with no interior vapor barrier therefore reducing the possibility for trapping moisture in the wall cavity.

However, is there the chance you would be creating a place for condensation to build between the foam and the studs? If I were to use the product I would use a product such as Rainslickr as a rainscreen for the ease and speed of installation.

Asked by Jason Macdonald
Posted Aug 1, 2012 10:47 PM ET
Edited Nov 30, 2012 9:08 AM ET


5 Answers

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Answered by Armando Cobo
Posted Aug 1, 2012 11:09 PM ET


1. We need to know your climate.

2. Read this article: Calculating the Minimum Thickness of Rigid Foam Sheathing.

Answered by Martin Holladay, GBA Advisor
Posted Aug 2, 2012 4:40 AM ET


Does it make a difference that the foam is to the interior of the sheathing? Typically, when rigid on the exterior of a wall is discussed, it involves the rigid being placed to the exterior of the wood sheathing, which is why thickness matters, because you want to keep the sheathing warm.

But in the ZIP sheathing case, how is it different than just adding additional insulation to the cavity, as the exterior of the sheathing is still exposed as in a typical wall? The perm rating for the 1" foam product is around 2 perms.


Answered by Jill Neubauer Architects
Posted Nov 30, 2012 8:50 AM ET


As long as you don't install a low-perm siding, it should be fine. (Examples of claddings that limit outward drying include adhered manufactured stone veneer and stucco with acrylic admixtures.)

Anyone who is worried about the ability of the sheathing to dry outwards should install a ventilated rainscreen gap between the siding and the sheathing. (Something that is always a good idea, by the way.)

Answered by Martin Holladay, GBA Advisor
Posted Nov 30, 2012 9:01 AM ET
Edited Nov 30, 2012 9:11 AM ET.


Thanks Martin
We would be using cedar shingles probably over home slicker cedar breather.

Answered by Jill Neubauer Architects
Posted Nov 30, 2012 9:42 AM ET

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