Radiant barrier on Zip R-sheathing
Trying to finalize my exterior wall design. As of right now it’s going to be a 2×6 wall with Rockwool Comfortbatt for an R 23 rating in the cavity. I was then going to use ZipR with 1″ of rigid foam which touches the studs for a thermal break and an additional R6 rating. The ZipR is the main moisture and vapor barrier after it is fully sealed with their Liquid Flash system. I am looking to put a Radiant Barrier on the Zip on the Sun facing sides and perhaps the entire house that has a Perm Rating of 6. This will be under the Hardie Board siding which is attached to 3/4 inch furring strips for a rain screen.
My question is will a Perm 6 Radiant Barrier Wrap allow any moisture that get’s under it to dry fast enough in a climate zone 4, Western Tennessee, area to avoid any damage to the Zip Wall System?
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Replies
Not an answer to your question, but if you want a radiant barrier, why not do regular zip with foil faced poly-iso on the outside? In either situation, I'm pretty sure your drying method for the sheathing is to the inside only.
I thought about it but there are a couple of reasons I rather use a Radiant Barrier.
1. WIth the Zip R in 10' sheets I can sheet the outside from bottom plate to top plate with 1 10' sheet then just fill in the gaps in the rafter tails upto roof line when we pressure block the rafters at the wall plate. I will end up having a continuous insulation barrier all the way to the roof deck which my engineer has okayed for ZipR also.Then I will have a vented soffit. I like the idea of a single sheet of Zip with minimal horizontal seams to waterproot.
2. Labor. Zip is 1 trip for insulation and waterproofing vs. 2 trips for sheathing and then foam. I know I may have to pay a little more labor for my RB on the outside but I dont' really have to do the entire house, where I would with the foam to maintain the insulation factor.
Plus I like the way I can detail windows and doors with the zip system vs. exterior foam. That part is just a personal perference.