Exterra provides an effective air control layer by default, so technically speaking, you don’t need any additional house wrap. So, regardless of the method you go with, you’ll have that integral air barrier in your wall.
Why Adding a Layer of CI Is the More Cost-Effective Way to Increase Effective R-Value of Above-Grade Walls
Simply adding a layer of CI, such as Halo’s Exterra, can give you a whopping 34.5% R-Value boost, while only increasing your costs slightly. This method also creates a higher thermal lag, leading to reduced long-term energy costs.
Halo Exterra performs two functions in a building enclosure assembly (thermal resistance + functions as the water control layer with sealed joints), whereas Comfortboard by Rockwool only performs a single function providing a somewhat lower thermal resistance.
WILL 2 LAYERS OF EXTERRA STILL BE PERMEABLE? No. Two layers of Exterra will not meet the minimum requirement of being “permeable”, which is 60 ng/Pa-s-m2, or 1 perm. A single layer of Exterra maintains it’s breathability up to a maximum thickness of 2” (71 ng/Pa-s-m2 or 1.2 perms at 2”). Exterra panels are laminated […]