Zip R Sheathing – Climate Zone 6
I received great feedback from my question about crawl spaces so I’m back with another question. Building a new home in Vermont (Climate Zone 6) and learned that Vermont Efficiency program now requires R9 (2″) exterior rigid insulation. I was planning on using the Zip R6 ( 1 1/2″ rigid insulation) which has been standard practice in the area, but it now doesn’t meet the requirement. The Zip R9 (2″) is problematic because the sheathing is too far from the studs and does not provide adequate structural shear bracing resulting in a wobbley frame.
Two alternative methods were suggested:
1) attach 1/2″ plywood sheathing directly to studs for structural sheathing and then mount Zip R9 panels onto the plywood. Add rainscreen detail onto the Zip R9 panels
2) attach Zip R6 (1 1/2″ rigid) to the studs and then add 1/2 – 3/4″ rigid insulation on the sheathing face of the Zip panel and building wrap over the added rigid insulation. Add rainscreen detail over the assembly above.
My gut is that option 1 is better but I would appreciate any/all feedback and comments you might have.
Thanks in advance . . . . I love this forum!
Blake
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Replies
What is the appeal of Zip+R for you? I don’t see paying a premium for something that weaken the building.
Now that exterior foam is all but required on all the new builds finding someone to install the foam and siding should be easy as it is so common.
I like my Zip sheeting with foam on the exterior at the time no one want to install the foam.
I think if you price out zip with 2 inches of exteriod foam sleeper rain gap siding you get a better wall for less money. Be sure to look for used/reclaimed foam.
Walta
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You don't need to brace the whole building, usually only section. What you can do is corner brace with 7/16+R6 Zip and R9 for the rest. Bracing can also be done with let in bracing which I think would be the simplest as all your sheathing is now the same. Zip R can itself be used for bracing but the nailing pattern is very tight.
I find working with exterior rigid pretty easy, I would build with 1/2" CDX plus 1.5" to 2" polyiso but your local trades might disagree.