GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Radiant barrier on Zip R-sheathing

DesertKnight67 | Posted in General Questions on

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?

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.


  1. etekberg | | #1

    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.

  2. DesertKnight67 | | #2

    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.

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |