Zip Sheathing durability vs plwyood and self-adhered WRB
After reading countless posts on this site, I am so excited to post here myself! My name is Derek and I am still in the early planning stages for a small 2 story 3 bedroom house (1300 square feet) in zone 5 that I plan on building myself. My priorities are affordability, durability, energy efficiency, and ease of construction, in that order. I am weighing benefits for some components of my wall assembly. I am somewhat committed to the following assembly: Fiber cement siding, 3/4 inch rain screen, 2 layers of 1.5″ comfortboard 80, A WRB/air barrier of some sort, 2×6 Studs 24″ O.C. with mineral wool batts and finally 5/8 drywall.
At first, I was leaning towards zip sheathing as the WRB and air barrier with huber’s liquid flash product sealing the nail holes, joints between sheathing, and around and on my window bucks. My concern is in the lack of durability (priority #2) and permeability of the Zip sheathing. Yes, I know the assembly can always dry to the interior regardless of how permeable the Zip is, but I want a vapor open wall that can ideally dry in both directions. Right? The consensus seems to be that plywood is both more durable when exposed to moisture and more vapor permeable. This makes me lean towards a self-adhered WRB/air barrier with 1/2″ CDX as the sheathing. Would this be a significantly safer route if and when my house has wet sheathing?
Switching from Zip sheathing to plywood and a self-adhered WRB would be a more expensive and time consuming assembly. If the CDX and WRB assembly is in fact more durable, is the improved durability significant enough to justify the decrease in affordability (priority #1)?
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